Lighting Retrofit Manual
Technical Report Lighting Retrofit Manual
TR-107130-R1
Final Report, April 1998
Prepared for Electric Power Research Institute 3412 Hillview Avenue Palo Alto, California 94304
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Copyright © 1998 Electric Power Research Institute, Inc. All rights reserved. REPORT SUMMARY
Lighting retrofits offer many benefits for building owners, building users, and electric utilities. Among the most important are reduced electricity demand, significant energy savings, and lower building operating costs. This handbook provides a resource for utility representatives that explains the technical and financial considerations of lighting retrofits, describes the most popular retrofit possibilities, and illustrates sound retrofit decision making.
Background Lighting accounts for 30-35% of electricity use in commercial buildings. High efficiency lighting retrofits can cost-effectively save from 30-50% of this energy while enhancing the visual environment and improving lighting quality. Most lighting retrofits pay for themselves through energy savings in less than five years; indeed, in many cases, simple payback occurs in under three years. When occupant satisfaction and worker productivity are factored into the economic analysis, lighting improvements produce immediate benefits.
Objective To develop a handbook that will help utility representatives provide building owners with concise, accurate, up-to-date information on lighting retrofits using energy- efficient technologies.
Approach Lighting professionals developed the handbook based on their collective experience in performing lighting audits for utility programs, energy service companies, building owners, and design professionals. EPRI personnel and other lighting industry professionals reviewed the handbook for accuracy and relevance.
Results This handbook—which may serve as a training manual or a reference—provides readily accessible information on the following key topics: x The importance of lighting retrofits, including a summary of when retrofits make sense as well as the role of the utility in the retrofit process x The lighting retrofit process, with step-by-step examples and illustrations
iii x The basic technologies used to improve lighting systems in existing buildings, with emphasis on lamp/ballast, luminaire, and control technologies x Retrofit opportunities for commercial, industrial, and outdoor lighting system types
The handbook includes a quick reference checklist of all lighting retrofit opportunities for use by lighting auditors. Nine appendices provide information on power quality as well as how to calculate illumination levels, measure illumination levels in the field, perform cost-effectiveness calculations, and collect field data. The appendices also summarize other EPRI tools and publications and provide a glossary of terms.
EPRI Perspective Retrofitting existing buildings with more efficient lighting devices is both an easy and cost-effective way to reduce building energy use and operating expenses. Lighting retrofits make the most sense in the following circumstances: excessive illuminance of all or portions of the building, use of lighting equipment over 10 years old, lamps and luminaires that have been poorly maintained, operation of lighting for more hours than needed, high electricity and/or demand charges, and suboptimal lighting conditions. Among the most significant and immediate benefits of retrofitting outdated lighting systems are an improved luminous environment, reduced lighting energy and building operating expenses, and decreased lighting maintenance. These benefits can lead to increased worker productivity, greater economic competitiveness, and cleaner air. Although other building system retrofits—including premium efficiency motors, variable-speed drives, and improved building automation and control—are effective and desirable, lighting retrofits generally require lower capital investment, have a higher return on investment, and are more appealing to building owners.
This handbook is one of a series of EPRI lighting documents designed to assist utility representatives. The Lighting Fundamentals Handbook (TR-101710) provides basic information on vision, physics, electrical equipment, and design practice. EPRI's Advanced Lighting Guidelines (TR-101022, R1) offer a more comprehensive understanding of modern lighting equipment and specific application guidelines on the use of energy-efficient sources, luminaires, and control equipment. Finally, LightPAD 2.0 serves as a portable audit and design tool for evaluating retrofit lighting options.
TR-107130-R1
Interest Categories Key Words Building systems and analysis tools Lighting Lighting Control systems Energy management and controls, Luminaires office automation Energy efficiency Daylighting
iv ABSTRACT
This handbook is a general reference for utility representatives that explains the technical and financial considerations of lighting retrofits, describes the most common retrofit technologies and illustrates sound retrofit decision making. The handbook is organized in five chapters. Chapter 1 is an overview of the issues and benefits related to lighting retrofits. Chapter 2 presents details on the process of evaluating a building to determine if lighting retrofits make sense. Chapter 3 covers the basic lighting retrofit technologies including lamp/ballast technologies, luminaire retrofit opportunities, and control strategies. Chapter 4 summarizes lighting retrofit opportunities for various lighting system types including general commercial, industrial and outdoor systems. Chapter 5 is a quick look-up matrix retrofit opportunities which summarizes the more detailed information in Chapters 3 and 4. The handbook is supported by nine appendices with useful reference information on how to calculate illumination levels, measure illumination levels in the field, perform cost-effectiveness calculations, and collect data in the field. Other appendices address issues related to power quality, summarize other EPRI tools and publications, and define terms and concepts in a glossary. The handbook may be used as a training manual or as a reference.
v
ACKNOWLEDGMENTS
This handbook was written by Charles Eley of Eley Associates with valuable contributions from James R. Benya of Pacific Lightworks. Miriam Phillips was responsible for copy editing and Irene Chan for graphic design. A thorough technical review was provided by Don Aumann and Larry Ayers of Bevilacqua-Knight, Inc. Karl Johnson of EPRI was the project manager.
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CONTENTS
1 OVERVIEW...... 1-1 Introduction ...... 1-1 Significance of Lighting Retrofits...... 1-2 Benefits of Retrofitting...... 1-3 Lighting Quality...... 1-3 Reduced Energy Costs...... 1-3 Reduced Lighting Maintenance ...... 1-5 Capital Availability...... 1-5 Economic Competitiveness ...... 1-5 Cleaner Air...... 1-5 Good Public Relations ...... 1-6 Improved Lighting and Productivity...... 1-6 When Lighting Retrofits Make Sense...... 1-8 Excessive Illuminance ...... 1-8 Inefficient Technology...... 1-9 Poor Maintenance...... 1-9 Long Hours of Operation ...... 1-10 High Electricity and/or Demand Charges...... 1-11 Suboptimal Lighting Conditions (Deferred Capital Re-Investment) ...... 1-11 The Role of the Utility...... 1-11 Barriers ...... 1-11 Demand-Side Management (DSM) Programs...... 1-12 The Retrofit Process ...... 1-13
2 THE LIGHTING RETROFIT PROCESS ...... 2-1 Overview ...... 2-1 Diagram of Process ...... 2-1 Participation by the Utility Representative ...... 2-2
ix The Players...... 2-4 Information Resources...... 2-5 Qualification Phase ...... 2-6 Data Collection Phase...... 2-9 Plan Survey ...... 2-9 Interviews with Building Operators ...... 2-11 Lighting Survey (Audit) ...... 2-12 Engineering Phase...... 2-16 Lighting Quantity and Quality Issues ...... 2-16 Lighting Schedules ...... 2-22 Confirming Assumptions...... 2-32 Retrofit Approaches—Relamping vs. Redesign...... 2-33 Estimating Energy Cost Savings...... 2-34 Replacement and Maintenance Costs...... 2-40 Economic Analysis...... 2-41 Construction and Commissioning Phase ...... 2-41 Bid Documents ...... 2-41 Bidding and/or Negotiation ...... 2-42 Construction...... 2-42 Lamp and Ballast Disposal ...... 2-42 Asbestos...... 2-43 Commissioning ...... 2-43 Verification and Measurement...... 2-43 Ongoing Maintenance...... 2-45
3 RETROFIT TECHNOLOGIES ...... 3-1 Lamp/Ballast Technologies ...... 3-1 Relamping Retrofit Opportunities...... 3-1 Lamp Performance Measures ...... 3-3 Lamp Efficiency and Energy Legislation...... 3-8 Tungsten Halogen Lamps...... 3-12 Compact Fluorescent Lamps...... 3-13 Full-Size Fluorescent Lamps ...... 3-16 High-Intensity Discharge Lamps...... 3-22 Luminaire Retrofit Technologies ...... 3-42 Optical Reflectors ...... 3-43 x Lenses ...... 3-52 Control Technologies ...... 3-54 Retrofitting Occupancy Sensors ...... 3-54 Dimming Controls ...... 3-57 Timers and Time Clocks...... 3-60 Powerline Carrier Controls...... 3-62 Photocells ...... 3-63 Photosensors...... 3-63 Latching Switches...... 3-64
4 LIGHTING SYSTEM TYPES ...... 4-1 General Commercial ...... 4-1 General Commercial Lighting Systems ...... 4-1 Fluorescent Troffers ...... 4-2 Incandescent Downlights...... 4-7 Fluorescent (non-troffers) ...... 4-12 HID Lighting Systems ...... 4-16 Commercial Decorative Lighting...... 4-19 Commercial Utility Lighting ...... 4-23 Exit Signs and Other Self-Illuminated Signs ...... 4-25 Track Lighting ...... 4-26 Industrial...... 4-28 Industrial Fluorescent ...... 4-28 Watertight Fluorescent...... 4-30 HID High Bay Area and Aisle...... 4-31 HID Low Bay Area and Aisle...... 4-32 HID Vaportight ...... 4-33 Special Purposes/Environments...... 4-34 Outdoor ...... 4-34 Street and Road Lights...... 4-34 Floodlights and Billboard Lights...... 4-35 Wallpacks ...... 4-36 Bollards...... 4-36 Parking Garage Fixtures...... 4-37 Step Lights...... 4-37 Landscape Lights...... 4-38
xi 5 SUMMARY OF RETROFIT OPPORTUNITIES ...... 5-1 Commercial...... 5-1 Industrial...... 5-6 Outdoor ...... 5-9
A GLOSSARY OF TERMS...... A-1
B BIBLIOGRAPHY...... B-1 EPRI Reports and Fact Sheets ...... B-1 Lighting Bulletins, Handbooks, and Reports...... B-1 Applications ...... B-2 Videotapes...... B-2 Brochures ...... B-2 Fact Sheets...... B-2 Software...... B-2 IESNA Publications: ...... B-3 General...... B-3 Recommended Practices...... B-3 Light Energy Management...... B-3 Other Publications:...... B-3 Associations, Societies, and Institutes ...... B-5 Ordering Information ...... B-7
C EPRI’S LIGHTING ANALYSIS TOOLBOX...... C-1 Lighting Audit Software: LightPAD 2.0 ...... C-1 Daylighting Analysis: Building Energy Estimation Module (BEEM) ...... C-1 Lighting and Other Building Systems: COMTECH ...... C-2 Lighting Evaluation System (LES)...... C-2 Post-Retrofit Calibration and Commissioning: Lighting Diagnostics and Commissioning System (LDCS)...... C-2
D CALCULATING ILLUMINATION LEVELS...... D-1 The Lumen Method...... D-1 Coefficient of Utilization (CU)...... D-2 Room Cavity Ratio...... D-3 Light Loss Factor ...... D-3 Point Source Calculations ...... D-5 xii E MEASURING ILLUMINATION LEVELS ...... E-1 As-Is Measurements vs. Initial Lumen Measurements ...... E-1 Photometers and Calibration...... E-2 Measurement Procedures...... E-3 Measurements in Daylighted Areas...... E-4 Task Lighting ...... E-4
F CALCULATING COST-EFFECTIVENESS ...... F-1 Introduction ...... F-1 Payback Period...... F-1 Net Present Value (Life-Cycle Cost)...... F-1 Benefit-to-Cost Ratio ...... F-5 Internal Rate of Return ...... F-5 Annualized Cost...... F-5 Other Issues...... F-6 Inflation and Energy Cost Escalation Rates...... F-6 Tax Considerations...... F-6
G POWER QUALITY...... G-1 Supply Voltage ...... G-1 Voltage Regulation ...... G-1 Voltage Transients...... G-2 Voltage Surges and Sags ...... G-2 Voltage Interruption ...... G-2 Power Factor...... G-3 Harmonic Distortion...... G-3
H LIGHTING SURVEY FORMS...... H-1 Suggested Data Structure ...... H-1
I LIGHTING EDUCATION AND LABORATORY FACILITIES...... I-1 Utility-operated Centers ...... I-1 Lamp Company Centers ...... I-4
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1 OVERVIEW
Introduction
Building owners frequently turn to utility representatives for information and guidance on energy-efficiency issues, including lighting equipment retrofits. This handbook is a resource for utility representatives that explains the technical and financial considerations of lighting retrofits, describes most of the common and/or popular retrofit possibilities, and illustrates sound retrofit decision making. The book addresses primarily one-for-one retrofits, but does not address new fixture replacements.
This handbook is one of a series of lighting documents and resources produced by EPRI. Others include the Lighting Fundamentals Handbook, TR-101710, which provides basic introductory information on vision, lighting physics, electrical equipment and design practice; the Advanced Lighting Guidelines, TR-101022, R1, which offers a more comprehensive understanding of modern lighting equipment, containing specific application guidelines for the use of energy-efficient sources, luminaires and control equipment; and LightPAD 2.0, a portable audit and design tool for evaluating retrofit lighting options. Appendices B and C list publications and software available from EPRI.
This handbook is organized into five chapters. x Chapter 1 provides information on the importance of lighting in building energy use and the magnitude of opportunities to save energy; summarizes the benefits of lighting retrofits and when they make sense; discusses the role of the electric utility; and reviews the lighting retrofit process. x Chapter 2 presents details on each step of the lighting retrofit process; discusses short-term monitoring and when it should be used; and contains examples and illustrations of each step. x Chapter 3 presents information on the basic technologies used to improve lighting systems in existing buildings. The chapter is organized in three sections: lamp/ballast technologies, luminaire technologies, and control technologies. x Chapter 4 describes each of the important lighting system types (commercial, industrial, and outdoor) and addresses the retrofit opportunities for each type. Both general information and retrofit opportunities are presented for each lighting system type.
1-1 Overview x Chapter 5 summarizes all lighting retrofit opportunities presented in the two previous chapters into a quick reference or checklist for use by lighting auditors.
In addition to the five main chapters, the handbook has nine appendices that are provided for reference. x Appendix A: Glossary of Terms. A definition of terms used in the handbook and in the lighting profession. x Appendix B: Bibliography. A listing of publications from EPRI and others that will provide additional information on lighting retrofits. x Appendix C: EPRI’s Lighting Analysis Toolbox. A summary of EPRI software for assisting in the lighting retrofit process. x Appendix D: Calculating Illumination Levels. A brief explanation of the lumen method of calculating illumination levels in spaces. x Appendix E: Measuring Illumination Levels. Details on how to measure lighting levels in spaces, including calibration of instruments and accounting for dirty luminaires and/or aged lamps. x Appendix F: Calculating Cost-Effectiveness. Definitions of simple payback, life- cycle cost, net present value and other terms used in evaluating the cost- effectiveness of lighting retrofit opportunities. x Appendix G: Power Quality. Information on power quality issues related to lighting retrofits. x Appendix H: Lighting Survey Forms. Recommended data organization and sample survey forms for making audits. x Appendix I: Lighting Education and Laboratory Facilities. List of education and laboratory facilities for studying lighting technologies.
Significance of Lighting Retrofits
Energy-efficient lighting retrofits make good economic sense for most commercial buildings. Replacing aged lighting components with advanced energy-efficient components can save as much as 40% of a building's lighting energy costs while maintaining or enhancing the quality of the visual environment in the modern workplace. Most lighting retrofits pay for themselves through energy savings in less than five years; indeed, in many cases, simple payback occurs in under three years. When occupant satisfaction and worker productivity are factored into the economic analysis, lighting improvements produce immediate benefits.
Lighting represents a major end use in commercial buildings, accounting for approximately 30–35% of commercial sector electricity consumption. Lighting retrofits
1-2 Overview can cost-effectively save from 30–50% of this energy. American business is under constant pressure from abroad to increase productivity and cut costs.
Lighting improvements are a cost-effective investment that reduces building operating costs and can improve worker productivity.
Benefits of Retrofitting
Lighting retrofits have many benefits for the building owner, the building users, and the electric utility. The most important and direct benefits are reduced electricity demand, energy savings, and lower building operating costs. Less quantifiable benefits, such as improved lighting quality and possible productivity boosts, may be even more important.
Figure 1-1 Lighting’s Strategic Importance
Lighting Quality
Probably the most important benefit of a lighting retrofit is an improved luminous environment. In addition to saving energy, lighting retrofits can correct pre-existing lighting problems by providing adequate illumination, reducing flicker, and controlling glare.
Reduced Energy Costs
The most obvious and immediate benefit of retrofitting an outdated lighting system is reduced lighting energy and related operating expenses. In fact, this is often the only benefit considered in assessing the cost-effectiveness of lighting retrofits. Lighting 1-3 Overview retrofits reduce both electricity use and demand. The savings include direct reductions in lighting power and hours of lighting operation as well as indirect air conditioning energy savings (there is less heat to remove from the building). A retrofit can occasionally achieve a 50% reduction in the lighting share of the electric bill. The total electric bill for a typical office building can often be reduced by 20–25%.
Example 1-1 How Much Energy Can Be Saved?
U. S. commercial buildings contain approximately 300 million fluorescent troffers and 400 million fluorescent strip lights and industrial luminaires. These fixtures mostly employ four-foot rapid-start lamps. It is a reasonable assumption that some 80–90% of these luminaires are equipped with relatively antiquated T-12 lamps and magnetic ballasts. If these fixtures were retrofit with electronically ballasted T-8 lamps, input power would be reduced by an average of about 12 watts per lamp.1 This would reduce peak demand by over 20,000 megawatts, save 60 billion kilowatt hours annually, and reduce operating costs by $4.8 billion per year. This impact would result from one simple lighting retrofit. Other retrofits, such as replacing incandescent lamps with compact fluorescent lamps, could also result in dramatic savings.
Retrofitting existing buildings with more efficient lighting devices is both an easy and cost-effective way to reduce building energy use and operating expenses. Although other building system retrofits, including premium efficiency motors, variable-speed drives, and improved building automation and control, are effective and desirable, lighting retrofits generally have a higher return on investment and are more appealing to building owners. In addition, well-designed lighting retrofits are aesthetic and can improve worker productivity, while most other types of improvements are less visible to the building users.
1 The range is 6–16 watts of savings per lamp.
1-4 Overview
Reduced Lighting Maintenance
Most energy-efficient lighting retrofits also reduce maintenance costs. In many existing buildings, lighting system maintenance occurs only when there are equipment failures such as lamp and/or ballast burnouts. Routine group relamping and fixture cleaning are the exception rather than the rule. Since lighting retrofit programs usually involve significant equipment replacements, they are often overcoming 10 years or more of neglect and offer an opportunity to initiate new maintenance procedures that can reduce maintenance costs in the long term while rejuvenating the building's appearance and sense of brightness. Future maintenance costs associated with old ballasts can be eliminated, and lamps will not need to be replaced as often since energy-efficient products almost always have longer lives. This is especially true when incandescent lamps are replaced with longer-lived compact fluorescent lamps. Retrofit programs provide a windfall of savings in the first year by installing all new lamps and can provide the economic benefit of deferring ballast replacement by 20 years.
Capital Availability
Projected energy savings from lighting retrofits can be used as “equity” to finance the improvements. This capital is available through utility programs as well as energy service companies (ESCOs) that will finance retrofits through future energy savings. Often it is possible to package improvements so that older building equipment needing replacement can be included as part of the retrofit program.
Economic Competitiveness
Lighting retrofits enable companies to reduce costs and become more competitive in the world economy. This can result in greater economic growth for regions that actively promote lighting retrofits.
Cleaner Air
A great deal of electricity is produced through gas-, oil- or coal-fired generation plants, and the combustion process adds pollutants to the atmosphere. These pollutants contribute to global warming, acid rain, and other environmental problems. Energy savings through lighting retrofits can significantly reduce these emissions. The Environmental Protection Agency (EPA) has estimated the emission reductions associated with electricity energy savings (see Table 1-1).
1-5 Overview
Example 1-2 Reducing Air Pollution
The 60 billion kilowatt-hours of annual energy savings in Example 1-1 would eliminate 96 billion pounds of carbon dioxide emissions, 320 million kilograms of sulfur dioxide emissions, and 170 million kilograms of nitrogen oxide emissions.
Good Public Relations
Not only do lighting retrofits save energy, operating costs, and air pollution, they can help foster a more positive image for customers that implement the improvements and the utilities that promote the improvements. Participation in the Environmental Protection Agency's "Green Lights" program is based in large part on EPA’s success in promoting a positive image for participating companies.
Improved Lighting and Productivity
It is very difficult, some would say impossible, to document and quantify the relationship between lighting retrofits and worker productivity. Few persons would argue, however, that improving the visual environment hurts productivity. On the contrary, there is little doubt that workers will be more productive if glare is removed from computer screens, the electric light provides better color rendering, and flicker is eliminated. The difficult thing is assigning a monetary value to these benefits.
Figure 1-2 The Cost of Doing Business2
1-6 Overview
Table 1-1 Pollution Reductions Associated with Electricity Energy Savings
Emission Reductions per kWh of Electricity Savings Carbon Dioxide Sulfur Dioxide Nitrogen Oxide (g) Reduction (lb) Reduction (g) By Generating Source Gas 1 1.4 0.0 2.4 Oil 1 1.9 3.7 1.5 Coal 1 2.4 9.0 4.4 Averages by Region Region 1 (CT, MA, ME, NH, RI, VT) 2 1.1 4.0 1.4 Region 2 (NJ, NY, PR, VI) 2 1.1 3.4 1.3 Region 3 (DC, DE, MD, PA, VA, WV) 2 1.6 8.2 2.6 Region 4 (AL, FL, GA, KY, MS, NC, SC, TN) 2 1.5 6.9 2.5 Region 5 (IL, IN, MI, MN, OH, WI) 2 1.8 10.4 3.5 Region 6 (AR, LA, NM, OK, TX) 2 1.7 2.2 2.5 Region 7 (CO, MT, ND, SD, UT, WY) 2 2.0 8.5 3.9 Region 8 (CO, MT, ND, SD, UT, WY) 2 2.2 3.3 3.2 Region 9 (AZ, CA, HI, NV) 2 1.0 1.1 1.5 Region 10 (AK, ID, OR, WA) 2 0.1 0.5 0.3 National Average 3 1.6 5.3 2.8 Notes 1. Source: R. Arnold Tucker, Microcomputer Software for Evaluating Lighting Operations, Energy Engineering, Vol. 90, No.1, 1993. 2. Source: U. S. Environmental Protection Agency, Green Lights Lighting Upgrade Manual, September 30, 1994. 3. Weighted average based on 57% coal fired, 5.5% oil fired and 9.4% gas fired.
Salary expenses dominate the cost of doing business, and only the slightest improvement can be quite significant. Based on a 1990 national survey of large office buildings, salary costs represented $131 per square foot, almost 85 times greater than electricity costs which are estimated to be about $1.53 per square foot (see Figure Error! Reference source not found.). A productivity increase of as little as 1% would just about equal the entire annual electric bill.
Another way to illustrate the impact that lighting retrofits can have on worker productivity is to cite some examples3. x Pennsylvania Power & Light retrofitted the lighting system in a drafting room. The retrofit cost was $8,362 and energy cost savings were $2,035 per year. In addition, absenteeism went down by 25% and the rate at which drawings were produced went up 13.2%.
3 Ibid.
1-7 Overview x Hyde Tools retrofitted the lighting system in one of its facilities at a cost of $98,000. In addition to energy cost savings of $48,000 per year, the company estimates that its product worth increased $25,000 per year (due to productivity increases). x Boeing Aircraft company retrofitted the lighting system in one of its manufacturing plants. Not only did the company save 90% of the electricity costs for lighting, it experienced a 20% improvement in detecting imperfections. x The U. S. Post Office in Reno, Nevada, installed a new ceiling system and retrofit the lighting system in its postal processing facility. As a result it saves $22,400 per year in energy costs and enjoys a 6% increase in the processing rate.
These examples all represent cases where the lighting retrofit improvements were justified on the energy savings alone. The increases in productivity were an unexpected additional benefit. In each of these cases, there was no change in management style. Productivity was monitored routinely before the retrofit and continued to be monitored in the same manner after the retrofit.
When Lighting Retrofits Make Sense
Lighting retrofits make sense any time lighting energy can be saved cost-effectively. This usually results when one or more of the following conditions exist in a building. x Excessive Illuminance. A majority of spaces in the building are overlighted. x Inefficient Technology. The lighting equipment is more than 10 years old. x Poor Maintenance. Lamps are beyond their useful life and luminaires are poorly maintained. x Excessive Hours of Lighting Operation. Lighting is operated for more hours than needed. x High Electricity and/or Demand Charges. More money is saved per kWh or kW reduction. x Suboptimal Lighting Conditions. There are inadequate or poorly maintained lighting systems that need to be modified anyway.
Excessive Illuminance
Buildings that are overlighted are always candidates for lighting retrofits. Most unmodified buildings constructed before 1980 are likely to be overlighted for several reasons. x The wide acceptance of fluorescent lighting during the 1950s and 1960s made it technically possible to design lighting systems with high illumination levels. Customarily, excessive lighting was installed in the belief that more was better.
1-8 Overview x Before the 1980s, the lighting levels recommended by the IESNA and other construction guidelines were considerably higher than today’s standards. x Visual tasks have changed. Since the early 1990s, many workers spend much of their time in front of a computer screen, and paper tasks have improved greatly due to laser printers and xerography.
To examine whether a space is correctly illuminated or whether it is over—or underlighted, compare the actual light levels in the room (obtained by measurement or calculation) to the recommendations of the IESNA (Illuminating Engineering Society of North America). Procedures for determining light levels and comparing them to the IESNA recommendations are summarized on page 2-10.
Inefficient Technology
The efficiency of lighting equipment has markedly improved since the energy crisis of the early 1970s. Much of this improvement has been accompanied by improvements in lighting quality as well. For instance, electronic ballasts eliminate fluorescent flicker and T-8 lamps have better color rendering. However, older inefficient equipment is still in common use, and its replacement is a primary strategy in lighting retrofits. Table 1-2 presents examples of inefficient technologies and their possible efficient replacements.
Table 1-2 Retrofit Technologies for Lighting Efficiency
Existing Technology Energy-Efficient Replacement
Standard fluorescent magnetic ballasts Energy saving or heater cutout electromagnetic ballasts “Energy saving” fluorescent ballasts Electronic ballasts Standard fluorescent lamps T-8 or T-5 lamps (rare earth phosphor) F40T12 (F30T12, F20T12) FO32T8 (F25T8, F17T8) F96T12 F96T8, F96T8/HO Other T-8 or T-5 lamps of other types Incandescent “A” lamps Compact fluorescent lamps Incandescent “PAR” and “R” lamps Halogen and halogen IR lamps Mercury vapor lamps High-pressure sodium and metal halide lamps Metal halide lamps Reduced wattage metal halide lamps Metal halide electromagnetic ballasts Electronic ballasts Wall switches Motion sensor switches
Poor Maintenance
1-9 Overview
Poor or infrequent maintenance results in dust and dirt accumulation on lamps and fixtures. This interferes with light delivery and reduces the efficiency of luminaires. Poor maintenance also results in the use of lamps that are beyond their rated lives. Old lamps use the same power as new ones but produce significantly less light. Neither of these conditions actually increase energy use (except in the case of low pressure sodium lamps), but they can result in light levels that are well below those the system was designed to deliver. This can be a significant problem in an "aggressive" retrofit in which the design light level is very close to the IES recommended maintained level. In such a design, more frequent and thorough maintenance is necessary to ensure that maintained light levels remain at or above IES recommended levels.
Long Hours of Operation
Even a small improvement in lighting efficiency (power reduction) can save a considerable amount of energy when the lighting system is operated almost continuously. Long hours of lighting operation typical of hospitals, police stations, correctional facilities, etc. make most retrofits easy to justify.
Long hours of operation may also point to the need for automatic lighting controls such as time clocks, occupancy sensors, and other devices. One of the most needless—and common—wastes of energy is the operation of lights in unoccupied spaces. The savings can be enormous. While efficient equipment can reduce lighting energy use by as much as 50%, turning lights off saves 100%. Consider the following control opportunities when planning lighting retrofit projects. x When activities conform to a regular schedule, time clocks or an energy management system can be used to schedule lighting. x Spaces with irregular use can benefit from the use of occupancy sensors. Such controls are available to replace wall switches in small areas. x In large areas, occupant sensors can be installed on the ceiling. Some controls incorporate photo sensors for daylighting control as well. Many occupant sensors combine both infrared and ultrasonic detection methods to prevent false readings in rooms with sedentary occupants. x Spaces with sporadic occupancy can be equipped with interval timers that turn off the lights after a specified time period. These timed switches, available in both mechanical and electronic versions, generally replace existing toggle switches.
Regardless of the control devices used, information programs for the building users are important. Many people believe that it wastes energy to turn off lights for short periods of time. The truth is that fluorescent lights and incandescent lamps should always be turned off when not necessary. Signs located on doors and near switches can remind occupants to turn off lights when they leave a room.
1-10 Overview
High Electricity and/or Demand Charges
When rates are high, it is easier to justify investments in efficient lighting. While the cost of the retrofit remains the same, the energy cost savings are much greater. Lighting retrofits that would otherwise be marginal are likely to be cost-effective.
Because utilities must base their power delivery potential on anticipated peak use, they attempt to reduce the magnitude of those peaks through demand charges and differential billing rates, in which the price charged for electricity is substantially higher during peak-demand periods than during off-peak hours. This peak period is generally during the afternoon, when the use of office equipment and air conditioning is at its highest. Strategies that minimize electric lighting during peak hours—such as daylighting, task lighting, and careful controls—will return proportionally greater savings than those that reduce electricity use during off hours.
Suboptimal Lighting Conditions (Deferred Capital Re-Investment)
Although the focus of this handbook is on retrofitting lighting systems to save energy, it is important not to lose sight of the connection between a high-quality visual environment and the increased well-being and productivity of the occupants. Buildings that have inadequate lighting systems probably already need improvements. Through the use of efficient lighting technologies, lighting energy use can remain constant or even fall as a building’s lighting systems are renovated. Capital re-investment may be minimized through incentives or other benefits of new lighting systems.
The Role of the Utility
In spite of the enormous benefits and the availability of energy-efficient lighting technologies, significant barriers deter building operators from embracing newer technologies. Often, utility customers mistrust newer products, due to confusion about the technology, codes, standards, and the risk of construction disruptions to ongoing business operations. Utility demand-side management (DSM) programs have demonstrated that customers will move toward more energy-efficient lighting solutions.
Barriers
Resistance to lighting improvements occurs in response to any or all of the following factors: x perceived high initial costs of lighting improvements x no perceived need to save energy
1-11 Overview x lack of understanding about the advantages of better lighting x mistrust about the reliability of newer technologies x confusion over a bewildering assortment of products x confusion and mistrust about unsubstantiated claims of energy savings made by some lighting equipment manufacturers x concern about disruptions to business during construction
For the most part, these perceptions are caused by simple ignorance, which the utility can overcome through intelligent marketing techniques targeted at increasing customer awareness about improved lighting products and energy efficiency. Resistance to change will evaporate with the realization that lighting retrofits mean reduced operating costs, a greater ability to compete economically, environmental benefits, and improved worker productivity.
Demand-Side Management (DSM) Programs
Utilities have effectively used DSM programs to manage economic growth with fewer economic and environmental costs than would result by building new power plants. In addition, an environmentally-conscious public prefers the DSM alternative over construction of new power plants.
DSM programs require that utilities invest capital in human resources, equipment, and programs that will influence the consumer's use of energy. Successful programs reduce demand and energy use at a cost less than that needed to construct new generation capability. “Least-cost planning” is a term which applies to the process of carefully evaluating energy savings opportunities along side opportunities to increase generating capacity. Lighting retrofits usually surface as one of the most cost-effective ways to reduce electricity demand and energy use. Lighting retrofits can represent up to 80% (in some cases) of utility DSM investments4. In addition, lighting improvements are usually the most noticeable efficiency improvements in buildings, and they have a tremendous visual impact on building occupants and visitors.
Utility DSM programs can employ a number of strategies to promote investment in energy-efficient lighting. These include providing general customer service; directly participating through subsidiary energy service companies (ESCOs); performing lighting audits for customers and making recommendations; subsidizing the cost of lighting improvements through rebates, grants and financing; helping owners and designers to select efficient lighting equipment and to assess lighting options;
4 Frey, Donald J., Stuart S. Waterbury, Karl Johnson, LES, An Innovative Development for Lighting System Performance Evaluation, Journal of the Illuminating Engineering Society, Volume 25 Number 2 Summer 1996, pp 117-127.
1-12 Overview purchasing savings through demand-side bidding; and providing education and demonstration facilities to the general public and to lighting professionals.
Of these three strategies, subsidizing lighting improvements has the greatest potential impact. Utility rebates can significantly reduce the installed costs, thereby accelerating payback periods and enhancing return on investment and life-cycle cost savings. The resultant increase in the economic value of a lighting improvement makes the project significantly more attractive to decision makers. Similarly, grants and attractive financing programs also encourage building owners to initiate lighting improvements and save energy.
The Retrofit Process
Details of the retrofit process are presented in Chapter 2. Table 1-3 summarizes some of the key points.
Table 1-3 The Retrofit Process
Phase Purpose Tasks
Qualification Determine if the building is a good Evaluate the quality of lighting in the space and candidate for lighting retrofits assess the potential for improvements
Data Collection Collect information needed to perform Plan Survey the engineering study Interviews Short-Term Monitoring Audit/Survey
Engineering Identify lighting retrofit opportunities, Assess Quantity/Quality Issues evaluate their cost-effectiveness, and Determine Lighting Schedules make recommendations Confirming Assumptions Retrofit Approaches—Relamping vs. Redesign Estimate Energy Savings Estimate Retrofit Costs Economic Analysis
Construction and Commissioning Implement cost-effective Bid Documents recommendations Bidding and/or Negotiation Construction Lamp and Ballast Disposal Asbestos Commissioning Verification and Measurement
1-13 Overview
The retrofit process will undoubtedly be different for each project, depending on its size, complexity, and the magnitude of the opportunities. Clearly, not all the tasks listed in Table 1-3 will be carried out for every project. At one extreme, a lighting retrofit project might consist of going to the local hardware store and buying some screw-in compact fluorescent lamps to replace incandescents. At the other extreme, it can involve a detailed audit, short-term monitoring of the lighting system, engineering feasibility studies, prototype installations, bidding and negotiations, commissioning, and post-construction evaluation.
One of the tasks that is becoming more common with retrofit projects is to install short- term monitoring equipment, such as portable data loggers, to accurately measure hours of lighting operation and determine the magnitude of the savings that are possible with occupant sensors and other types of automatic lighting controls. In the past, it was common just to assume 4,000 hours/year for lighting system operation. Studies have shown that actual hours can vary by 30% or more, creating significant errors in the prediction of energy savings. Short-term monitoring used to be a very expensive task; but with modern equipment, good data can be obtained at a very reasonable cost. This makes short-term monitoring, for instance through EPRI’s Lighting Evaluation System (LES), the recommended procedure for an increasing number of lighting retrofit projects.
1-14 2 THE LIGHTING RETROFIT PROCESS
This chapter presents details of the lighting retrofit process, focusing on the development of a typical project from determining feasibility to commissioning and verification of energy savings. EPRI and others have developed tools to assist in the preparation of lighting audits, and to analyze the information that is collected. These tools are referenced when appropriate. A special effort is made to review the communications that should occur between the various individuals and organizations in each stage of a lighting retrofit project. Particular emphasis is directed to communication with the utility representative.
Overview
There are many variables that affect the lighting retrofit process such as the size and complexity of the building and the implementation method, e.g. utility audit with separate construction contracting by owner; energy service company providing a complete service, including financing; or some other implementation method. In spite of these significant variations, the nature and sequence of activities in a lighting retrofit have been fairly well established over the years, through trial and error. The lighting retrofit process as presented in this chapter is as generic as possible. Most of the steps will be carried out no matter what the implementation method or the building complexity.
Diagram of Process
Figure 2-1 is a flow chart of the general lighting retrofit process. The process is described briefly here and more detail is provided later on each of the steps. The process begins with a qualification audit to determine if retrofit opportunities are significant enough to warrant a more detailed audit and engineering study. If the project has significant opportunities, then it will proceed through three phases: the data collection phase, the engineering phase, and the construction phase. Usually at the completion of the engineering phase, some type of report or feasibility study is delivered to management (or the decision makers) and a commitment is made to carry out the construction. The project then goes into the construction phase where bid (or construction) documents are prepared, the improvements are carried out, the systems commissioned, and in some cases, post-construction monitoring and evaluation are performed.
2-1 The Lighting Retrofit Process
Participation by the Utility Representative
Communication between the utility representative and building owner or facility manager is important at all phases of the retrofit process, but is critical at the beginning. Many owners will have no previous experience with lighting retrofits and the support and encouragement of an electric utility may be just what is needed to push them to the point of considering a lighting retrofit.
Beyond the initial promotion of lighting retrofits, the services that the utility representative may provide will depend on programs in effect at the time. As mentioned in Chapter 1, these programs may range from design assistance, where the utility may provide some or all of the auditing and engineering feasibility services, to financial incentives or rebates, to possibly a turnkey service similar to energy service companies.
2-2 The Lighting Retrofit Process
Figure 2-1 The Lighting Retrofit Process
2-3 The Lighting Retrofit Process
The Players
In most cases, the utility will be intervening a lighting retrofit process that is already underway. The stage of the process and the players involved will usually be different for each building. To understand who the players are and what their roles are, you should ask the following questions:
Who initiated the lighting retrofit? Is the owner responding to a proposal from an energy service company; is there an in-house energy manager whose job it is to promote energy efficiency projects? Is pressure being applied on the landlord by an environmentally conscious tenant? Does the building owner simply want to increase profits by reducing operating costs?
How would the project be implemented? Is there a lighting maintenance company for the building? Does this company provide retrofit services? Would the lighting retrofits be designed, implemented, and financed as a turnkey project by an energy service company? Do the contracting policies of the organization require competitive bids? If so, is it acceptable to write closed specifications?
Who has the authority to commit to the project? Identify the individual or individuals who have the authority to make the go/no-go decisions. Does this person make a recommendation to a council or board? When does this board meet?
Is the proposed lighting retrofit a one-time project? If the building is part of a campus or one element in a collection of real estate holdings, there is a good chance that a successful lighting retrofit will lead to additional retrofits within the same organization.
Who will benefit from future energy savings and who will pay for the lighting retrofits? The answer to this question will help identify the motives of the various players and determine if there are conflicting interests in carrying out a lighting retrofit. In the ideal case, there will not be conflicting interests, e.g. the person/organization/department that pays for the lighting retrofits will enjoy the energy saving benefits. Unfortunately, there are many instances when conflicting interests exist. Following are some examples. x In some governing jurisdictions, the cost of the retrofits must be paid out of the operating budget of the department or agency that occupies the space. The benefits of saving energy, however, may not directly benefit that department/agency, but rather some other agency with the responsibility for paying utility bills or providing energy. x In multi-tenant leased facilities, the contractual details of the lease will determine which party is responsible for paying for the lighting retrofits and which party benefits from the savings.
2-4 The Lighting Retrofit Process
— With some leases, the monthly cost to the tenants includes everything, and the landlord is the sole beneficiary of energy savings. In many cases, the landlord would also pay for the lighting improvements, perhaps through an allowance for tenant improvements. The tenant would have no financial interest at all in the lighting retrofit, although they would be negatively affected by disruptions during construction and positively affected by improvements in lighting quality. — Other lease arrangements allow the owner to pass through operation costs for energy, janitorial, etc. to the tenants on a prorated basis. Tenants typically pay a fixed share of energy costs and there is no direct association with the energy use of the tenants own space. If a tenant takes measures to save energy, then they would enjoy only a portion of the savings (the rest would be prorated among the other tenants). — A third arrangement is for the tenants to pay their own utility bills. This is the opposite of the first case. The tenant would be the sole beneficiary of energy savings. Depending on the lease terms, either the tenant or the landlord may also be responsible for financing the improvements.
Information Resources
One of the most useful services that can be performed by the utility representative is to provide reliable and credible information. Depending on the nature of the project and the players involved (see above), the customer may be confronted with a plethora of information on available technologies and equipment. The utility representative can be of enormous assistance by acting as a buffer between the customer and the vendor community and by providing practical information about the expected costs and benefits of various approaches. Several lighting information resources are available to help with the preliminary analysis.
General Lighting Information
In most cases, the utility representative will be a valuable source of generic information about available technologies, expected benefits, case studies of successful retrofits in similar facilities, and details on the utility's incentive programs. The customer may ask the utility representative to evaluate product claims or suggest vendors. Potentially, this is a delicate subject. The most prudent response will usually be to provide general technical information on the available technologies or equipment types, pointing out the most relevant parameters to aid the facility manager in making an informed choice. Customers will find demonstration facilities to be an invaluable resource in sorting out competing technologies and manufacturer’s claims since these facilities allow customers to directly experience and compare lighting technologies. Appendix I is a listing of educational and laboratory facilities supported by utility companies, lamp manufacturers, and luminaire manufacturers.
2-5 The Lighting Retrofit Process
Vendor Presentations
Equipment vendors and installers often make direct presentations to utility customers. These presentations are generally targeted at selling products or services. Sometimes, claims of product superiority and energy savings may be exaggerated or based on inaccurate assumptions. When claims are contradictory or confusing, a cautious customer will seek additional information and clarification from the utility representative, an independent research or testing facility, or will visit one or more successful installations. Sophisticated customers may also set up test areas on their own premises for side-by-side comparisons of competing products. After narrowing the field to a manageable number, the facility manager will then obtain cost quotes from the remaining vendors and installers.
Independent Information
Independent research institutions such as EPRI, IESNA, and the Lighting Research Center publish many useful reports, fact sheets, and case studies on energy-efficient lighting technology. Facility managers rely on these publications for objective evaluations of current technology. Similarly, some states have energy boards or commissions that sponsor lighting research, publish results, set product standards, and develop building energy efficiency codes. In addition, many universities and national laboratories conduct research and issue publications on energy-efficient lighting products. On the federal level, the Environmental Protection Agency’s (EPA) Green Lights Program is a resource of both information and analytical tools for large-scale lighting retrofits.
Lighting Professionals
Lighting design and consulting professionals can provide expert opinions on the options confronting the facility manager. Some lighting professionals specialize in energy efficiency and retrofitting applications. However, the majority of most lighting design work consists of new construction or new lighting in conjunction with extensive remodeling. As such, a given lighting professional's experience with retrofitting existing installations may be limited. When there are issues of lighting quality or lighting problems that need to be addressed, the services of a qualified lighting professional should be secured.
Qualification Phase
This phase is a preliminary screening to determine if a detailed lighting audit and engineering feasibility study is warranted. The qualification step may consist of a quick walk-through of the building to observe the predominant type of lighting equipment and to make a few spot measurements of lighting levels. On the other hand, it may 2-6 The Lighting Retrofit Process consist of a quick review of the plans and a few phone calls. In most cases, the utility representative can assist the customer in making this determination relatively quickly and at a minimum cost.
To qualify (or disqualify) a facility, an experienced auditor or lighting professional can usually identify the major lighting system(s) from a walk-through of the building and quickly determine economic feasibility. For example, a building illuminated with 60- watt incandescent downlights operating 12 hours a day will likely be a cost-effective retrofit candidate. But a warehouse with skylights and photocell-controlled high- pressure sodium lighting is probably operating as efficiently as possible.
Example 2-1 Qualification of a Hotel Project
Consider a hotel in which the hallways are lighted with 75-watt incandescent downlights. The primary retrofit component would probably be compact fluorescent conversion kits. Each kit consists of a permanent socket, ballast, and reflector unit. 18- watt lamps would be used to maintain lighting levels similar to the existing condition. Each conversion kit would save an average of about 50 watts. At a utility rate of $0.08/kWh, electric costs would be reduced by about $4.00 per socket for every 1,000 hours of operation. If the conversion cost $50 per socket, it would take 12,500 hours to amortize its cost; if the conversion cost $75, payback would occur in 18,750 hours. A walk-through of the facility determined that some lights are operated 24 hours a day (8,760 hours per year), while others are operated about 12 hours per day (4,380 hours per year). Under these conditions, retrofitting the existing incandescents is almost guaranteed to be cost-effective, as under even the worst possible conditions (all lights operating 4,380 hours per year, $75 per unit conversion cost and no rebate offered), the conversion would pay for itself in 4.3 years. Simple payback would occur within the 5- year deadline that is usually considered to be the longest acceptable payback period.
2-7 The Lighting Retrofit Process
Table 2-1 Clues to Determining Feasibility
Cost-Effective When: May Not Be Cost-Effective When: x the facility has long hours of operation x the facility has relatively short hours of operation, or operation of the lighting x the lighting system was installed before occurs mostly at night 1980 and has not been modified x the facility has been designed to exceed x the electric utility has high demand the efficiency requirements of relevant and/or energy rates energy codes, such as California's Title 24 (1985 or later), ASHRAE/IES 90.1— x the utility actively practices DSM and 1989, including derivative codes in the offers substantial rebates for states of Washington, Oregon, replacement of lighting equipment Massachusetts, and Florida x the facility has apparently high lighting x the building is a Federal government levels facility that has been designed to comply with the DOE Standard or with x the facility has a preponderance of non- ASHRAE/IES 90.1 dimmed incandescent lighting x the facility pays relatively little for x other apparent and substantial energy- energy and peak demand saving opportunities exist (e.g. unrealized daylighting) x the facility is in a remote location or area where competitive pricing of retrofits might not be available
x the facility is not eligible for rebates or equivalent incentives
x the facility has recently undergone a successful lighting retrofit (there are cost-effective opportunities for old retrofits and poorly executed retrofits)
2-8 The Lighting Retrofit Process
Data Collection Phase
If the project passes the initial qualification (appears to be a likely candidate for a lighting retrofit), then the next step in the process is to collect more detailed data. This includes: x reviewing architectural drawings and lighting plans if they are available x interviewing building managers and/or operators x collecting utility billing history x installing short-term monitoring equipment to determine hours of lighting operation and other data (optional) x taking a detailed inventory of lighting equipment and controls on a space-by-space basis
Appendix H contains a suggested data structure and sample input forms for making a lighting audit. It might be helpful for you become familiar with the information in Appendix H before making your first audit.
Plan Survey
The first recommended step in collecting data is to make a plan survey. The plan survey is just like a walk-through survey, but is made by reviewing the plans. The purpose of the plan survey is to: x Identify similar spaces that can be treated together. Whether or not they can actually be treated as similar spaces will be confirmed during the audit phase. x Set up the data input forms and the data collection procedures. x Understand the electrical branch circuits in order to plan the possible installation of data loggers or other short-term monitoring equipment.
Often the most accurate “as built” drawings and specifications are located in the building engineer’s office at the building site. If this is the case, the plan survey might be scheduled as a part of the actual audit.
Similar Spaces
In most buildings it is possible to save time by reviewing the plans to identify spaces that are similar and performing a detailed audit on a sample of the similar spaces. It is not necessary for similar spaces to be truly identical. They should, however, be of
2-9 The Lighting Retrofit Process similar size, have the same type of lighting equipment, support similar visual tasks, and if daylighting is important, have similar windows and solar exposure.
Data Input Forms
It is a good idea to set up the data input forms during the plan review phase. A suggested data structure is presented in Appendix H along with sample data input forms. The surveyor should give each similar space a unique name and start a data input sheet for each space. It may be possible to fill out much of the information on the data input sheets from the plans, although all information should be verified in the field. The surveyor will eventually walk through the entire facility, entering any missing information on the data input sheets. Depending on the completeness of the available plans, the plan survey will provide some or all of the information listed below. x Project Level Information. Information at this level should include the name, address, phone numbers, etc. of the utility customer, the building, the utility, and the auditor. In addition, milestone dates are often recorded. See Appendix H for a suggested data structure and sample input form. x Lighting Fixture Schedule. If the plans include an electrical plan and lighting fixture schedule the auditor can save time by using this information to start a lighting fixture schedule. The lighting fixture schedule is a listing of each unique fixture type. The auditor should be aware that luminaires are often modified in the field and the information from the lighting plans should be considered a starting point only. When modified fixtures are discovered in the field, they should be added to the fixture schedule. In general, each fixture type is assigned a code along with other descriptive information. When the surveyor performs a space-by-space audit, fixtures can be associated with the space through the unique code. Information in the fixture schedule may also include luminaire performance data such as coefficient of utilization, which is needed to perform light-level calculations. x Space Level Information. Once similar spaces have been identified and organized, the auditor should measure and record the physical dimensions of each. Dimensions should include length, width, and ceiling height. This is also the best time to make note of orientation, fenestration details, and daylighted areas within the space. A daylighted area may be loosely defined as any area within the space that is adjacent to a window or windows, or that is under a skylight. See Appendix H for a suggested data structure and sample input form. When recording the luminaires for each space family, it is also a good idea to review circuiting and assess obvious opportunities for energy-saving lighting controls. Most lighting control possibilities are dependent on occupancy patterns and daylight availability, which should be confirmed during audit. However, the experienced auditor can usually recognize control opportunities from the plans.
2-10 The Lighting Retrofit Process
Electric Circuits
Identify dedicated lighting circuits for short-term monitoring of lighting hours. For some projects, you will want to install short-term data loggers or other monitoring equipment to determine typical hours of lighting operation and to verify base case lighting power estimates. There are many different types of data loggers, but a common type measures current in electric circuits. Frequently, lighting and plug loads will be on separate circuits so that the time of use of these circuits can be monitored on an hourly basis. A review of the electrical drawings is the easiest way to identify such circuits and to plan the installation of data loggers.
What You Should Have after Completing the Plan Survey
Upon completion of the plan survey, the surveyor should have a data sheet for each similar space, each with as much information as can be determined from the plans and schedules. Verify information gathered from the plans during the walk-through, as plans often differ from actual building conditions. If LightPAD 2.0 is being used to perform the audit, a project database would be started. The project database is essentially an electronic version of the data input forms contained in Appendix H. If using LightPAD 2.0, carry a notebook computer into the field with the program installed and the project database residing on the hard drive.
Interviews with Building Operators
Identify the person(s) responsible for the operation of the building and set up a time when they can be interviewed. If possible, schedule the interview at the building site, where the operator can show you problems and point out peculiarities. When scheduling the interview, identify pieces of information that you will need so that the operator can obtain this information prior to your interview. Use the following bullets as a checklist. Be flexible, however, and ask any other appropriate questions. x Try to get information on hours of lighting operation. Whenever possible, confirm information with occupants and custodial staff. See more information below. x Find out who the decision maker is, e.g. who will have the final say as to whether or not the lighting retrofit will be implemented. Try to learn what level of economic performance will be required for implementation, e.g. establish a maximum simple payback, or if life-cycle cost analysis is to be performed, determine the discount rate and study period. x Gain a better understanding of how the lighting retrofit (if cost-effective) will be implemented. Will they use their maintenance contractor, union contractor, energy service company, etc? You should know who will do the work and if possible consult with them before you estimate costs for the measures.
2-11 The Lighting Retrofit Process x Find out if the building has an energy management system and if the EMS has any data recording capabilities. If so data may already be available for estimating hours of lighting operation, which is needed for an economic analysis. x Learn about maintenance practices. Are lamps changed as a group? How often? How often are luminaires cleaned? If the lighting system is poorly maintained, ask what it would take to improve practices. x Find out what utility rate the building is on and get copies of previous utility bills. These bills will be helpful in determining an average cost of electricity if the rate used demand and/or time-of-use charges. This information is needed in the engineering phase to convert electricity savings into cost savings. See Appendix H for suggested data input forms.
Lighting Survey (Audit)
The next step in the process is to perform the lighting survey (or audit). A lighting survey may be done with in-house personnel or by specially hired and trained auditors. Product vendors sometimes offer lighting surveys, but they typically emphasize applications for their own products, possibly ignoring other products better suited to the application as well as other applications to which their products do not pertain. This survey is generally the most time-consuming step in the process and it is important to be organized and ready. Before you go to the site to perform the audit, you should already have a good idea of how many spaces you will need to visit from the plan survey.
The purpose of the survey or audit is to x Verify dimensions, fixture types, and other information collected during the plan survey. x Measure lighting levels and record information about the cleanliness of luminaires and the age of the lamps which may be needed in adjusted measured levels. x Interview space users about any lighting quality problems, e.g. is it too bright, too dim, or just right? Do they experience glare on their VDT screens? x Gain more insight about hours of lighting operation. Are manual switches located in each space? Are they used? x Determine the visual task(s) that are taking place in the space. x Take an inventory of lighting equipment in each space. Note the physical condition of the equipment, the type of housing, lamps, etc. If the equipment is already in the schedule, then you will only need to mark the ID number from the schedule and indicate the quantity. If the equipment is not in the schedule, then you should add it.
2-12 The Lighting Retrofit Process x If lighting level calculations are to be performed, record information about the reflectances of the walls, roofs, floors in addition to the physical dimensions of the space. x If the space has daylighting, measure the illumination with the lights turned off. Note the sky conditions at the time of the measurement. If possible take measurements under different sky conditions, e.g. bright and sunny, cloudy and overcast, etc. x Make note of retrofit opportunities.
The surveyor should have the following equipment and/or supplies: x light meter x measuring tape or infrared measuring device x notebook or clipboard with space data sheets or cassette tape recorder (for recording information to be transcribed). x camera (still or video) x notebook computer (if you are using LightPAD 2.0). Make sure you have spare batteries or enough battery life to complete the survey.
Data collected during a lighting survey should be as complete as possible. Advanced surveying tools such as EPRI's LightPad encourage data entry on the job site. This helps reduce data collection time, costs, and errors. Whether or not a computer is used in the field, a computer spreadsheet or database is a virtual necessity for managing large lighting surveys.
Most automated data collection procedures focus on replacement of specific luminaire hardware. Unfortunately, relying strictly on rules for one-to-one replacements can lead to rote component substitution retrofits. Such substitutions may suggest delamping or other retrofits that are inappropriate to the application at hand. It is strongly recommended that an experienced and knowledgeable lighting professional assist the auditor in identifying retrofit opportunities that go beyond simple parts-swapping. See Example 2-2 for an illustration of how a knowledgeable lighting professional can improve on a typical lighting retrofit strategy.
2-13 The Lighting Retrofit Process
Figure 2-2 The Well-Equipped Lighting Surveyor
Example 2-2 Going Beyond Energy Savings
An older office building with magnetically ballasted four-lamp lensed troffers on 8' by 8' centers is to be retrofit. For most automated retrofit databases, as well as most utility rebate programs, this is a classic retrofit situation with a textbook solution: convert the existing magnetically ballasted T-12 systems to T-8 lamps and electronic ballasts; delamp, going from four to two lamps; add a specular reflector to increase luminaire efficiency. In most building spaces this will provide 40–60 maintained footcandles, while reducing power by more than 50%.
However, a skilled lighting professional, noting the extensive use of computer VDT screens in the space, might suggest that retrofitting the troffers with VDT lenses or louvers instead of adding reflectors (with resulting lighting levels of 30–40 footcandles) would make more sense from a lighting quality standpoint. This option would reduce high angle glare and background-task luminance ratios, and would help prevent veiling reflections caused by the imaging of the luminaires in VDT screens. Since the cost of the lens is about equal to the cost of the reflector, and energy savings match that of the textbook solution, the owner and occupants would realize increased benefits. Being able to identify and report this opportunity is what separates the skilled retrofit professionals from mere mechanics.
2-14 The Lighting Retrofit Process
Table 2-2 Time-Saving Tips
Try dictating into a microcassette recorder instead of using pencil and paper. Your hands will be free to climb ladders and open luminaires while recording ballast model numbers and lamp codes. Mention door or room number, occupant's name, and describe each room as you walk in.
See if you can get a copy of a floor plan to make your own notations. Be aware that most plans will be inaccurate to some degree; try to note major differences for easier reference by others. Fire exiting plans will often be available, if nothing else.
Take your camera or video camcorder—the pictures will jog your memory later. Remember to note what pictures you took during your visit.
Photograph each lighting fixture type in the building and give it a name or tag like "F1" for fluorescent fixture #1. Use A for incandescent, L for low voltage, H for HID, X for exit signs, etc. Indicate substantial differences between indoor and outdoor luminaires. See the earlier discussion on Fixture Schedules.
Consider visiting some facilities at night to avoid interrupting occupants and explaining your purpose repeatedly. Be sure to arrange for alarms to be off. Visit the building again briefly during the day to observe how lighting is actually used. Night audits are also critical to confirm after-hours operation assumptions.
Consider possible energy conservation measures (ECMs) while you are still on site. You can optimize the amount of data you collect and minimize return trips. Install lighting time loggers on the first trip and remove them on the last trip to get the longest sample time.
When checking light level, use a good meter that is color and cosine corrected. (See Appendix E for information on measuring light levels.) Take readings on work surfaces, desks, or at work-surface-specified height. Take multiple readings around the room, or at least an average. Don't accidentally shade the meter with your body. Take readings with shades or blinds closed to simulate night.
Consult IES standards to determine appropriate lighting levels for different tasks. Memorize the recommended lighting levels and representative tasks for Tasks A-F.
Use an electronic distance measuring device rather than a tape.
Look at lamp stock, ballast stock, and fixtures in the midst of repair or maintenance in the building to determine the exact technology, especially when checking fixtures is difficult.
Be clever to determine the age of the lighting system in each tenant space. Note spaces with aged lighting systems more carefully; there will often be more cost involved but more credits based on deferred maintenance.
Note the operating voltage and means of control for each luminaire. If possible, use a voltmeter to determine panelboard bus voltage. Look carefully for hidden lighting devices, like autotransformers or electronic dimmers used to change light level.
Source: Washington State Energy Office
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Table 2-3 IESNA Recommended Illumination Levels
Category Activity Illuminance, FC Typical Spaces (Low-Medium-High) A Public spaces with dark surround 2-3-5 Basements, quiet rooms B Simple orientation for short visit 5-7.5-10 Corridor, Storage rooms, Night clubs C Workspace with few visual tasks 10-15-20 Lobbies, Courtrooms, Elevators D Visual task of high contrast (large) 20-30-50 Offices, general work space E Visual task of medium contrast (small) 50-75-100 Offices, intensive work areas F Visual task of low contrast (very small) 100-150-200 Drafting, art work, medical procedures G Category F for prolonged period 200-300-500 Delivery rooms, autopsy tables, very difficult assembly, inspection H Prolonged and exacting tasks 500-750-1000 Exacting assembly, dental work I Special visual tasks 1000-1500-2000 Cloth inspection and perching Source: IESNA Lighting Handbook, 1993
In most audits you will want to determine the existing illumination level in similar spaces. There are two general procedures that may be followed—calculations or measurements.
Calculations. The lumen method is the most common calculation method. This is the method used by LightPAD 2.0. It is documented in Appendix D and explained more in the next section.
Measurements. Procedures for making lighting level measurements are summarized in Appendix E and are described more in the next section.
Engineering Phase
During the engineering phase the tasks are to assess lighting quantity and quality issues, establish lighting schedules for use in making estimates of energy savings, identify lighting retrofit opportunities, estimate retrofit costs, predict energy savings, determine economic feasibility, recommend a course of action, and report the findings to management. In reality, there is not a clear line between the data collection phase and the engineering phase, as most auditors will note lighting quality problems and begin to identify retrofit opportunities while they are in the field.
Lighting Quantity and Quality Issues
Lighting Quantity
Lighting quantity or average illumination can be measured or calculated for each space and compared to the recommendations of IESNA or others (more is presented on this
2-16 The Lighting Retrofit Process later in this section). If a space is overlighted, there is an opportunity to reduce or tune the lighting level to what is needed. This will save energy and operating costs, and if the retrofit is not too expensive, the cost will be paid for through the energy savings.
If a space is underlighted, the auditor is presented with a dilemma. For most lighting audits, the general feasibility criteria is to recommend measures that will save enough energy to pay for the retrofit over some reasonable period of time. If a space is underlighted and a lighting retrofit is proposed to correct the problem, energy use and operating cost may be increased. Furthermore, the owner will have to pay for the retrofit. Unless the benefits of correcting the problem can in some way be quantified and factored into the analysis, a retrofit project that costs money and increases energy operating costs, by definition, cannot be cost-effective. Many lighting retrofit projects, for instance those with energy service companies, are financed through the energy savings. In such cases, if there are no energy savings, there is no project. While it is not the main purpose of energy efficiency lighting audits to uncover lighting problems such as underlighted spaces, the process of performing the audit usually reveals such problems; and it should be the responsibility of the auditor/surveyor to report such problems to the building owner and ask for direction1.
IESNA Recommendations
The IESNA recommends illumination levels for nine different categories of visual tasks. These are labeled A through I and are summarized in Table 3-3. These recommendations are determined by a consensus of lighting experts and establish an illuminance level for the average sighted person to perform the given visual task without impairment.
Low, medium, and high values are recommended for each illuminance category. The value to use depends on the following variables, commonly referred to as weighted factors. x Occupant or worker age. In general, older persons need more light than younger persons. x Room reflectances or reflectance of task background. More light is needed if contrasts are great. x Speed and accuracy. More light is needed if a critical visual task is being performed.
1 This problem is not unique to lighting improvements. It also occurs with retrofits to heating and cooling systems. The existing system may not be providing legal quantities of outside air or may not be maintaining comfort conditions. By correcting these problems, the HVAC retrofit project may actually increase energy use, or at least some of the savings will be negated by correcting the problems.
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Table 2- gives the weighting to account for these factors. Weightings are determined separately for Illuminance Categories A through C as opposed to D through I. For illuminance categories A through C you take account of occupant age and room surface reflectances, using the following steps.
1. Determine the weighting factors separately for occupant age and room reflectances. 2. Add the two weightings, e.g. if occupants are under 40 (weighting factor -1) and room reflectances are in the middle range (weighting factor 0), the sum would be -1. 3. If the sum is -2 use the lowest of the three recommended illuminances. If the sum is +2 use the higher. Otherwise, use the middle value.
A similar procedure is used for Illuminance Categories D through I, except weightings are determined for three factors and summed.
Table 2-4 Weighting Factors Used in Determining Recommended Illuminance Levels
Weighting Factor -1 0 +1 For Illuminance Categories A through C Occupant Age Under 40 40-55 Over 55 Room Surface Reflectance Greater than 70% 30–70% Less than 30% For Illuminance Categories D through I Workers Age Under 40 40-55 Over 55 Speed and/or Accuracy Not Important Important Critical Reflectance of Task Background Greater than 70% 30–70% Less than 30% Source: IESNA Lighting Handbook, 1993. See this document for more details.
Determining Existing Light Levels. There are two ways to determine lighting levels in existing buildings: through measurements or through calculations. Some auditing tools such as EPRI’s LightPAD 2.0 calculate the lighting level for each space so that it can be compared to recommended illumination levels.
Measurements. Measurements can be more accurate than calculations, but they are tricky. You must consider the cleanliness of the luminaires and age of the lamps. Lighting systems are designed to deliver a maintained illuminance, which is the illumination level that will be delivered at the end of the maintenance cycle, right before the lamps are replaced and the luminaires cleaned. If you take measurements right after new lamps have been installed and the luminaires cleaned, then it will be necessary to adjust the measured illumination. Similarly, if the lamps are beyond their recommended life and the luminaires are especially dirty, it may be necessary to clean the luminaires and replace the lamps before taking measurements. This will mean that the light level measurements will need to be adjusted for room surface dirt depreciation (RSDD) and lamp lumens depreciation (LLD).
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In spaces near windows or under skylights, you must take separate measurements with and without daylighting. Recommended methods for making measurements are documented in Appendix E.
Calculations. When measurements are not feasible, a standard calculation can also provide an estimate of average illumination. Appendix D presents the details of the Lumen Method, which takes into account room dimensions and surface reflectances, lamp lumen output, general characteristics of the luminaire, and the Light Loss Factor of the system. Because this mathematical technique estimates the average room illuminance, it will give misleading results if the room is illuminated very unevenly. Note also that the effects of daylighting and task lighting must be considered as well, because a low average illuminance estimate may be countered by natural light or task lamps.
If the space is evenly illuminated and the lumen method is an effective estimate, the value calculated can be directly compared to the recommended illumination level shown in Table 2-3.
Remedies. When a room is determined to have excessive illuminance, consider the following retrofits: x Replace existing lamps or lamp/ballast combination with lower lumen output system (e.g. standard lamps to energy savers, high-output lamp/ballast system to slimline, etc.). x Delamp existing luminaires; an additional option would be the installation of optical reflectors. x Install ballasts with lower ballast factors, resulting in reduced lamp lumen output. x Install dimmable ballasts with a photoelectric control system.
What to Do When There Is Too Much Light. Table 2-Error! Reference source not found. summarizes applicable technologies, advantages, and disadvantages if a space is overlit: remove fixtures; remove lamps; use lower power ballasts lamps; and dim the lighting system.
Lighting Quality
Lighting quality can be recognized but remains hard to specifically define. High- quality illumination can result from good designs using modest lighting equipment, yet the use of expensive lighting equipment does not guarantee good lighting quality. When lighting is retrofitted, it often presents an opportunity to improve the quality of the lighting as well as the energy efficiency.
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Physical Appearance. Most lighting systems that are candidates for retrofitting are older and have suffered periods of poor maintenance. Cracked and missing lenses, missing trims, parts that do not match, and other obvious problems are left unfixed for many years. Often the fixtures are dirty as well, and in extreme cases they are rusted, oxidized, and need painting.
Simply by cleaning and repairing the lighting system, its appearance is enhanced. It may also be a good time to paint the room’s ceiling or install new ceiling tiles, both to recover the reflectivity of the ceiling and to make the installation appear “as new.”
Color. Traditional cool white F40 lamps exhibit a greenish light long disliked by most people. Likewise, mercury vapor lamps also create an unpleasant and eerie light. Even warm white fluorescent lamps are of poor color quality, emphasizing orangish-yellow color tones.
The modern light source replacements offer lamps with significantly improved color. A typical fluorescent retrofit involving T-8 lamps naturally improves the color rendering index substantially; and at a minimum, space occupants usually observe that colors are more vibrant or people look better. While most of the time 4100K lamps are used to minimize before-and-after differences, sometimes the retrofitter uses 3500K lamps, which create a warmer-looking space as well. Similar results are possible in converting mercury vapor lamps to metal halide or compact fluorescent.
The traditional warm glow of incandescent light remains a preferred light source color. Fortunately, a retrofit with fluorescent, metal halide or HPS can yield the same color quality (or very close to it) provided the proper lamp is chosen. (Note that the wrong lamp can cause damage).
Elimination of Flicker. Flicker is inherent in light sources operated from AC power sources. In every light source from incandescent through high-pressure sodium, there is a presence of flicker that at a minimum can be annoying and that can cause headaches and other physiological reactions. In industrial and sports applications, flicker is stroboscopy, causing moving or rotating objects to appear moving differently from reality.
High-frequency electronic ballasts for fluorescent lamps and square-wave or DC ballasts for metal halide lamps can minimize flicker for these two important light sources. While they still flicker, the percentage is reduced considerably; and related problems, like stroboscopy are virtually eliminated.
Glare Control. There are two types of glare, discomfort glare and disability glare. Discomfort glare occurs when a light source is unshielded and very bright with respect to the surrounding surfaces. Disability glare occurs when glare obscures a visual task. Many sources of glare create both.
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Table 2-5 Options When There is Too Much Light
Remove Fixtures Remove Lamps Use Lower Power Ballasts or Dim the Lighting System Lamps
Often the existing spacing is This can often be done without Lower-wattage lamps are easy; Dimming ballasts are sufficiently close to allow further modification; but for low ballast factor for fluorescent expensive but offer other removing a percentage of the optimum results, reflectors or lamps is a clever solution. opportunities like daylighting; luminaires. In lay-in ceilings, other optical modifications might system dimming also works consider rearranging fixtures improve appearance. but without side benefits. so as to maintain acceptable spacing.
Applicable Technologies
Very simple and works well as Specular and white reflectors Low-wattage incandescent and Dimming electronic ballasts for long as spacing-to-mounting halogen lamps T-8 and T-12 lamps height is considered Reduced wattage T-12 lamps Dimmers for metal halide and (34- and 32-watt F40; 60-watt HPS systems F96; 95-watt F96/HO) Autotransformer voltage Impedance modifiers reduction to magnetic ballasts and tungsten loads (current Low-watt T-12 lamps for T-8 limiters) systems Waveform modification Low-wattage metal halide dimming to magnetic and tungsten loads Reduced light output electronic fluorescent ballasts
Advantages
Low-cost solution without A moderate-cost solution without Maintains the original Maintains the original concern for snap-back concern for snap-back. performance and appearance of performance of the lighting the lighting system at a lower system at a lower power level. Perform in conjunction with power level. retrofitting new technology (T-8, Perform in conjunction with CFL) for maximum savings Perform in conjunction with retrofitting new technology retrofitting new technology (T-8, (T-8, CFL) for maximum CFL) for maximum savings savings
Can permit dynamic controls like daylighting and demand management
Disadvantages
Can result in poor uniformity if Can result in a poorly- May offer too little reduction Cost and complexity with not done well maintained appearance dimming ballasts
Fluorescent lamp life problems with system voltage reduction
HID color shift
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Glare can be minimized by using lenses, louvers, or other forms of shielding. Some types of luminaires, like troffers, can be retrofit with lenses or louvers that improve glare control. In other cases, the addition of a lens or luminaire replacement can reduce glare.
Glare related to computer screens is the single most common disability glare problem encountered in retrofitting. Several lens and louver products exist that can be easily placed into plastic lens troffers to make them more suitable for computer work space. Because many older systems need new lenses anyway, the added cost of this feature can be quite low.
Too Much or Too Little Light. Too much light is a form of glare, causing discomfort or disability. Too little light can cause headaches, watering eyes, and other maladies.
Retrofits offer the opportunity to fix these problems. Because recommended lighting levels of the IESNA have dropped since 1970 in consideration of energy efficiency, many spaces are overlighted and a retrofit program benefits from decreasing the lighting levels to an appropriate amount. In fact, the success of many retrofit programs, particularly in the late 1980s, depended upon delamping and reduced lighting levels.
It is considerably more difficult to address too little light in a retrofit program. Increasing lighting levels, even if done efficiently, can increase energy use and undo the cost-benefit balance of a project. But because inadequate lighting levels are being “fixed,” it is generally recommended that this (and other types of remedial work) be isolated from both the energy-efficiency and cost-effectiveness calculations of the balance of the retrofit project.
Other Quality Issues. Many things can affect illumination quality as well as the perception of quality by occupants. For example, the proper location and tactile quality of a lighting control switch or dimmer can make an entire lighting system seem better. During the retrofit process, seek out small opportunities to convey a quality issue.
Lighting Schedules
One of the key tasks in the engineering phase is to identify and define the unique lighting schedules appropriate for the project. Once the schedules are identified, one is assigned to the lighting system in each of the spaces. In existing buildings, you can estimate annual lighting hours through interviews with the building manager or building owner, by projections from short-term measurements, or through an analysis of the utility billing history. There are three fundamental ways to define a lighting schedule: full-time equivalent (FTE) hours, FTE hours separated by time-charge periods, and hourly schedules. Each of these is discussed below.
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Full-Time Equivalent Hours
The simplest way is in terms of the full-time-equivalent (FTE) hours. If you know the annual electricity consumption for a lighting circuit (kWh) and the peak power (kW), the FTE hours is the kWh divided by the kW. FTE hours may be used to estimate the energy savings associated with reducing lighting power, and for flat utility rates with no demand charge, energy cost savings can also be accurately estimated.
FTE Hours Separated by Time-Charge Periods
If the utility rate for the project has time-of-use energy charges and/or demand charges that vary by time of use, it may be necessary to define lighting schedules in a more detailed manner by separating the hours for different time charge periods. For instance with many utility rates, the cost of electricity varies between summer and winter and by time of day. Table 2- shows how hours might be separated for a typical utility rate with time-of-use charges. For this utility rate, it is necessary to split the hours between five time-charge periods: summer on-peak, mid-peak, and off-peak; and winter mid- peak and off-peak. The details of the utility rate define these periods by time of day, day of the week, and season. To make it easier to perform the calculations, you should separate days that define on-peak, mid-peak, and off-peak differently. For each time- charge period, you should multiply the hours per day times the number of days per year. For instance in Table 2-, lighting is operated for six hours during the summer on- peak period from noon to 6:00 PM and there are 126 summer week days in the year. The total lighting hours at the summer on-peak rate is therefore 756. This process is repeated for the other time-charge periods.
Table 2-6 Lighting Schedule with Time-of-Use Charges
Full-Time-Equivalent (FTE) Hours
$/kWh Weekday Saturdays Sun./Hol. Total
Summer On-Peak 0.12 6 h/d u 126 d n.a. n.a. 756
Summer Mid-Peak 0.08 5 h/d u 126 d 4 h/d u 26 d n.a. 734
Summer Off-Peak 0.04 3 h/d u 126 d 3 h/d u 26 d 2 h/d u 30 d 516
Winter Mid-Peak 0.07 6 h/d u 127 d 4 h/d u 26 d n.a. 866
Winter Off-Peak 0.03 8 h/d u 127 d 3 h/d u 26 d 2 h/d u 30 d 1154
Total n.a. 4026
With time-of-use rates, it is necessary to separately estimate energy savings for each time-charge period so that the correct rate ($/kWh) can be applied.
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As a shortcut, some auditors calculate the virtual rate and use this in the same manner as a flat rate. The virtual rate can be calculated from the utility bills by dividing the total cost for electricity by the total consumption for a given time period. The time period can be for an entire year, or for greater accuracy, you can calculate a separate virtual rate for summer and winter.
Hourly Schedules
The most detailed way to define a lighting schedule is by hour of the day. This detail is needed by hourly simulation programs such as DOE-2. For each hour of the year, you indicate the lighting power through a multiplier. The multiplier is usually a fraction of the peak lighting load. With computer programs such as DOE-2, hourly schedules are built up. First, you divide the year into seasons. Next, you divide the weeks in each season into day types, e.g. weekdays, Saturdays, and Sunday/Holidays. Finally for each day type, you specify a 24-hour lighting profile like those shown in Figure Error! Reference source not found..
The detail you include in your lighting schedules will depend on (a) the resources you have to perform the audit (obviously it takes less time to define a schedule in terms of FTE hours); (b) the tools you have at your disposal, and the data available to you (to construct hourly schedules you must have data from an EMS or measurements from portable data loggers); (c) the type of utility rate that applies to the project; and (d) the method you plan to use to estimate energy savings (if you plan to capture the HVAC interactions by using an hourly simulation program then you will need hourly schedules). If you need an hourly schedule, EPRI’s Lighting Evaluation System (LES) provides an example of one approach to develop one (see Appendix C). You might also consult ASHRAE/IESNA Standard 90.1—1989, which has default hourly lighting schedules for about 10 building types.
Figure 2-3 Example Hourly Lighting Schedule
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General Approaches to Acquiring Data on Lighting Operation
There are several ways to collect data on the hours of lighting operation. These include:
1. Observing and/or Noting Use Patterns. This method relies heavily upon common sense and its reliability is uncertain. The key is to interview a wide range of people from the building management staff to regular occupants to custodial staff. For instance, by interviewing building management employees, one can generally determine use patterns for certain types of lighting systems, like retail store lighting, classroom lighting, etc. where hours of operation are very predictable. However, even in many of these situations the manager may not be aware of off-hour operations, such as how long the cleaning crew leaves the lights on in the middle of the night; so night audits are important. Also, there may be seasonal variations in light use that management is not aware of.
2. Using Recording Meters to Record Power Use on Lighting Circuits. This is a good way to get a “snapshot” of daily use profiles of lighting energy in office buildings, schools, and other buildings, provided that the lighting circuits are isolated from other loads. The power use profile measurements can be averaged over a sample period; from them, a reasonable profile of building lighting energy use can be established for those circuits being measured. These profiles can be the building blocks for hourly schedules (see above). Choosing which circuits to measure is the key to this method. However, even if the circuits are well selected, this technique still fails to provide time-of-use data for any particular light fixture or application. Also, seasonal differences will not be detected unless data are collected for an entire year. The EPRI Lighting Evaluation System uses an advanced type of recording system (see Appendix C). 3. Using Historical Lighting Use Data from an Energy Management System. Some modern energy management systems are programmed to enable tenant use of lighting during preprogrammed periods and then require tenants to request and pay for extended hours of lighting operation. This method of wiring and controlling the building effectively distributes energy cost differentials in the building among tenants without submetering. If the historic use data for each tenant are available, it may be possible to construct accurate lighting use profiles including seasonal differences. As above, however, data will generally not be provided for specific fixtures or applications. 4. Install Cumulative Lighting Loggers. Cumulative light loggers are self-contained lighting-activated instruments that record the amount of time a specific electrical light is energized. For the time period in which it is installed, the logger will accumulate FTE hours. For modeling small buildings with simple electric rates, this is a very good method; but for larger buildings with complex electric rates, cumulative light loggers will not provide data to enable you to split the hours among the time-charge periods. 5. Install Light Profile Loggers. Some loggers record both the time and duration of lighting use. Such loggers will record temperature, electric current or illumination levels, each of which can be associated with lighting use. At the end of the measuring period, the logger is connected to a computer to download the time- series data. This method is very accurate for the luminaire or circuit being
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measured. If enough recording loggers are used, detailed use patterns of specific rooms and lights can be generated.
Each of these methods of determining time of use produces data of increasing accuracy as the sample period and number of sample points increases. In particular, it is important to determine any seasonal variations that might taint the profile. Quarterly samplings can resolve this problem.
Practical Data Collection
As a practical matter, the surveyor will often have a little of each type of data. Engineering judgment and common sense can help sort through the data and construct reasonable schedules for use in analysis. With a minimum amount of time to take measurements, and often a limited instrumentation budget, it is still possible to obtain sufficient information to use in retrofit analysis. The following steps are suggested:
1. Interview building operators, users, and custodial staff to determine as much about lighting systems operations as possible. 2. Observe lighting operations at different times: early morning, late afternoon, evening, weekends, etc. 3. Gather any data available from an energy management system or electric submeters. 4. Based on observations and interviews, identify the number of unique lighting schedules that exist in the building. This may include several “manual” schedules. 5. Use portable data loggers to collect (or supplement) information on each of the unique lighting schedules identified above. For representative lighting circuits or luminaires, collect data for at least one week. If the profile is simple and obvious, with a clear-cut schedule and a consistent load, it can be used to establish the baseline and help with analyzing retrofit options. 6. If there is a clear profile but with load changes throughout the day, data loggers can be placed within luminaires suspected of having time-differing use patterns. 7. If there is not a clear profile, data loggers can be placed within luminaires suspected of having differing schedules. 8. For spaces with daylighting controls or in spaces that are candidates for daylighting controls, consider using a light logger to determine times when useful daylight is available. Keep in mind that seasonal and weather variations can be significant. Calibrate the light logger with an accurate light meter.
For each luminaire, it should be possible to create an average daily profile. The most difficult will be fixtures in daylighted spaces, especially if manual control is involved.
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Other difficult situations include similar spaces, like private offices, under the manual control of the occupant.
Typical Schedules
Hours of lighting operation are very dependent on the building type. For instance, buildings that are always open, such as hospitals, will operate their lighting systems for more hours than an average office building, which is only open during the day. A 1986 study by the U. S. Department of Energy found that the lighting systems in the average nonresidential building operate for 3,500 hours per year, but that the hours vary considerably with building type. Estimates by building type are summarized in Table 2-, and these values may be used in calculations when better data are not available.
Table 2-7 Hours of Lighting Operation Typical Values
Building Type Annual Hours of Operation* Building Type Annual Hours of Operation*
Assembly 2760 Mercantile 3325
Education 2605 Office 2730
Food Sales 5200 Public Order & Safety 6365
Food Service 4580 Warehouse 3295
Health Care 7630 Others 4400
Lodging 8025
Source: Energy Information Administration, U. S. Department of Energy.
* Based on 50 weeks per year operation
Short-Term Measurements
The availability of modern building monitoring and verification equipment has dramatically improved the ability to estimate accurately operating hours for lighting systems. A wide variety of inexpensive, pocket-sized, battery-operated data loggers are available for making short-term measurements. Data loggers are available to sense light, occupancy, electric current, electromagnetic fields, temperature, relative humidity, and other parameters. Data loggers of most interest in lighting retrofit work sense light, occupancy, or electric current. However, other types of sensors can be used. For instance, temperature sensors can be used to monitor the on/off state of a luminaire if the temperature sensor is placed near the ballast. Data loggers record information in one of three ways, described below: x Run-time loggers. Some loggers record cumulative hours, commonly called run- time loggers. These loggers usually sense only whether a condition is true or false, e.g. current is passing through a conductor or it is not, a space is occupied or it is
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not, or light is being produced by a luminaire or it is not. When using this type of logger, you must determine the lighting power through other means. x Time-of-use loggers. Time-of-use loggers work like run-time loggers, but record the times the state changes. For instance, they record the time when current begins to pass through a conductor and the time when current stops. Again you must determine lighting power through other means. x Quantity loggers. Finally, some data loggers record the strength of the signal, which can be converted to a quantity of current, temperature, light level, etc. This type of data logger takes a snapshot of the quantity at specified time intervals, adjustable from about 5 minutes to a couple of hours.
Both time-of-use and quantity data loggers usually come with hardware and software that enables information to be uploaded to personal computers through a serial port. The various types of portable data loggers most applicable to lighting retrofit work are summarized in Table 2-.
In addition to miniature, portable, self-contained data loggers such as those described above, more complex data monitoring systems can be constructed from basic components. For instance, general purpose, multichannel data loggers are available that will measure and record information from both analog and digital sensors. With this type of system, you can separately select sensors to measure current, temperature, light, occupancy, or just about any other signal.
Table 2-8 Summary of Portable Data Logger Types for Lighting Retrofit Work
Type Run Time: Time Of Use: Quantity: of records the cumulative Records the time At specified time Type Sensor hours when: at which: intervals, measures:
Occupancy Passive infrared or a space is occupied a space becomes occupiedn.a. ultrasonic or unoccupied
Light Photocell a luminaire is on a light is turned on or off light level
Electric Current Clamp-on current sensor current is flowing current begins to flow or current ceases to flow
Note: Other data loggers are available to measure temperature, voltage, relative humidity, and other variables.
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Example 2-3 Using Monitored Data
An office space is leased to a law firm. Most of the space consists of 40 private offices which are controlled by manual switches. A series of lighting retrofits is being evaluated, including occupant sensors and retrofitting the luminaires with T-8 lamps and electronic ballasts. In order to estimate the savings, a schedule is needed to represent the current hours of lighting operation for the private offices. A second schedule is needed to represent the pattern of lighting operation that would occur if all the offices had occupant sensors.
A sample of four private offices are selected at random (10% of all offices). This sample will be used to determine schedules for all the private offices. Two data loggers are installed in each office. The first is a time-of-use data logger that records the state of the lights. Data from these data loggers will be used to construct a schedule representing current lighting operation. The second data logger is a time-of-use occupancy data logger. This will provide information that will be used to modify the first schedule. Both data loggers are installed for a period of two weeks. Since there are no holidays during this two week period, the data loggers will collect information for 10 weekdays, two Saturdays and two Sundays.
Most quantity data loggers take a snapshot of the signal strength at specified time intervals, which can be set on the data logger. If the data logger were set to record current every 30 minutes on the hour and half-hour, then all that would be recorded would be the current at those instances. If for some reason, the current came on for a short period of time around the hour and half-hour and was off the rest of the time, most quantity data loggers would not detect this. Although this is usually not a problem, more advanced quantity data loggers are available that integrate the signal over each time interval. Suppose that current was zero for the first 15 minutes of a 30 minute time step and 10 amps for the second 15 minutes. A standard quantity data logger would record 10 amps, while the integrating type would record the average over the time period of 5 amps.
The type of data logger that is appropriate for your job depends on the type of schedule that you need to develop (FTE hours, FTE hours separated by time-charge period, or hourly). If you need only FTE hours, then the cumulative type data logger is appropriate and will save time in analyzing data. By measuring the hours of operation for a typical week, an annual schedule can be projected.
Before embarking on a short-term monitoring effort, you should do some planning. Based on your judgment and observations of the building and its lighting systems, identify the unique lighting schedules that you believe to exist in the facility. You may be able to estimate the hours of operation for some of the schedules without monitoring
2-29 The Lighting Retrofit Process data. For instance, the schedules in hallways and other common areas are usually very predictable and a reasonable estimate can be made through interviews with users and operators of the building. Concentrate on those schedules for which you need monitored data.
When using data loggers that record current, be sure to account for the power factor when converting to energy kWh. Most data logger software is set up to make this adjustment. A good way is to correlate the current to the power measurement from a portable watt meter.
EPRI’s Lighting Evaluation System and Lighting Diagnostics and Commissioning System both use portable data loggers. See Appendix C for more information.
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Example 2-4 Determining Hours of Lighting Operation
A two-story office building of about 20,000 square feet has the following spaces and uses: x Common main lobby, 24-hour operation, 2,000 ft2. The lobby is always open and has a guard on duty. x Second floor elevator lobby and corridors, 24-hour operation, 1,500 ft2. It is always open. x Building core area, including stair towers and elevator shaft, 800 ft2. The stair lights are on emergency and always on. x Restrooms, 1,000 ft2. There is a switch at every restroom door and the guard is supposed to turn the lights off during off hours. x Mechanical, electrical, maintenance, and janitorial, 700 ft2. Each space has a switch but the lights are supposed to be left off. x Main floor tenant #1, 3,500 ft2, travel agent with open area, one conference room and two private offices. Business hours are 8:00 AM to 5:00 PM M-F and 10:00 AM to 5:00 PM Saturday. The office is generally empty by 6:00 PM. x Main floor tenant #2, 3,000 ft2, retail store, with 500 ft2 of back-of-house space. Business hours are 10:00 AM to 6:00 PM, Monday through Thursday, 10:00 AM to 9:00 PM Friday, and 10:00 AM to 5:00 PM Saturday. x Upper level tenant #3, insurance agency, 5,500 ft2, with 10 private offices, conference room, and open office area. Business hours are 9:00 AM to 5:00 PM M-F but the principals work 60 hours per week including evenings and weekends. x Upper level tenant #4, architect, with one large drafting room and a conference room. The office is generally open by 8:30 AM M–F by the receptionist but work hours are very flexible. x Building management indicates that cleaning occurs between 6:00 PM and 2:00 AM Sunday through Thursday. x The utility rate structure includes separate demand and energy charges with different energy rates for on-peak and off-peak. The peak period is 10:00 AM through 6:00 PM M–F.
Cumulative light loggers are placed in the following locations: rest room, store (front and rear), reception area of each office space, and several principals’ offices of tenant #3. Measurement period is a typical spring week. The available data are listed as follows.
Lighting System Normal Hours/Week Cleaning Hours/Week Logger Reading Comment Lobby, Elevator Lobby, and Core 168 n.a. n.a. Restrooms Unknown Unknown 135 Tenant #1— Reception 58 10 72 68 estimated, 72 measured, say 70 Tenant #2—Store 50 10 71 Stocking and/or close-out takes some time—use 70 hours Tenant #3—Reception 40 10 79 Reception lights on during late hours Tenant # 3—Principal A 40 10 77 Works late hours Tenant #3—Principal B 40 10 67 Normal hours Tenant # 4—Open Area Not sure 10 74 Makes sense
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Example 2-4 Determining Hours of Lighting Operation (continued)
From observations, it appears that the lobby, core, and shell lighting can be assumed to operate full time (168 hours/week). Meanwhile, almost all spaces seem to be operating about 70 hours per week (3,640 hours per year). All lighting operates during peak periods. From these data, the following chart may be developed.
Use Period Multiply Daily Hours By Annual On-Peak Annual Off-Peak Hours Hours
Business Day On-Peak 8 x 250 = 2000
Business Day Off-Peak 2 x 250 = 500
Weekend Day 10 x 104 = 1040
Holiday 10 x 15 = 150
TOTALS 2000 1690
For this example building, the annual use profile is 2,000 on-peak hours and 1,700 off-peak hours, for an annual total of 3,700 hours for tenant space lighting and 8,760 hours for public spaces lighting. As a check, this corresponds well to national averages of 3,500 annual office building lighting hours per year.
Confirming Assumptions
Each step in the process offers an opportunity to confirm assumptions made in the previous steps. It is not unusual to learn something along the way that affects the program, even to the point where a project is significantly changed or even abandoned. These data, welcome or not, should be continuously assimilated lest a project fails to meet performance requirements.
Some typical examples: x A scoping study might assume the use of 40-watt lamps (optimistic) or 34 watts (pessimistic) based on a rough fixture count. As the detailed fixture count is completed, an accurate count of EACH lamp type should be made to establish the best possible baseline. x Even in the “audit” phase, an assumption about the type of ballast is often made. The actual number of each type of ballast may not actually be known until luminaires are actually opened up for retrofit. In addition to the energy-related costs, the disposal costs of PCB-containing ballasts may also be impacted. Although at this point the project is committed, it still might be valuable to update the expected performance values. x Surprisingly, quite a few analyses discover that the utility rate being billed to the customer is incorrect. Checking this may reveal a rate too high or too low, or perhaps, a rate that might need to change because of the retrofit. x A dimming system might be discovered, such as an autotransformer or electronic dimmer. These systems, which were applied to branch circuits or panel boards,
2-32 The Lighting Retrofit Process
might be operating lighting systems at dimmed levels that are not readily obvious. These devices might not be discovered until construction, and once again, radically change the expected savings results. x Assumed hours of operations are frequently guesses. Even if the project is proceeding, data could be collected using loggers or even just observations by surveyors. Operating hours are among the most difficult data to accumulate anyway; so updating with more accurate data will only help create a more realistic baseline. x Cross-check assumptions with metered electrical data when it is available. Compare both energy (kWh) and demand (kW). If the building is on a time-of-use (TOU) rate, compare energy and demand for each charge period, e.g. on-peak, off- peak, etc.
Some projects require that energy savings predictions be met in order to meet economic performance criteria. In these cases, ongoing data input and corrections are essential to keeping the predictions as accurate as possible.
Retrofit Approaches—Relamping vs. Redesign
Often, the strategy of relamping must be compared with a decision to change the existing luminaires entirely. This is particularly relevant in situations where issues of lighting quality arise. Such a situation might arise, for instance, in an office with heavy video display terminal (VDT) use, illuminated by traditional fluorescent troffers. A common problem with lighting designs in areas of high VDT usage is the presence of veiling glare on the work task (the VDT screen), due to reflectance produced by the overhead fixtures. Relamping to more efficacious lamps in such a case will generally not solve the glare problem. Instead, the retrofitter must usually modify or replace the existing luminaires, often by installing small paracube louvers, or by using new fixtures such as indirect lighting. Alternatively, the existing luminaires (or work areas) could be relocated so as to move the source of glare away from the task zones.
Another application in which relamping may be incorrectly applied as a retrofit strategy occurs when poor lighting design or a change in occupancy or work patterns have created severely underlighted areas in the space. Sometimes, this problem can be solved by relamping with brighter lamps. However, there are situations where a simple relamping will not be sufficient to solve the lighting design problems. These conditions will require a complete redesign of the lighting system, including relocation and/or replacement of the existing luminaires.
2-33 The Lighting Retrofit Process
Estimating Energy Cost Savings
An essential task in evaluating whether an efficient lighting system is worth the additional cost is to estimate the annual energy use of alternative designs. With lighting systems, the energy used is simply the connected lighting power multiplied times the annual hours of operation. Both lighting power and the hours of operation are estimated separately for the base case and the lighting retrofit. Lighting power for the base case is determined from the audit. Lighting power for the retrofit condition is determined from engineering estimates or measured from test installations. The hours of operation for the base case can be reasonably estimated by interviewing the building managers, evaluating submeter data, or through the use of short-term monitoring (see earlier discussion). If automatic lighting controls are to be included as part of the retrofit package, the hours of lighting operation should be adjusted for the lighting retrofit case.
To calculate lighting electricity use when a time-of-use electric rate applies to the building, you will want to separate the hours of operation for each time-charge period and separately estimate electricity use for each time-charge period (see earlier discussion).
You should also consider the indirect benefits of reducing lighting power. Lighting systems add heat to buildings that must be removed by the air conditioner. Therefore, efficient lighting systems have the added benefit of reducing air conditioning load. Depending on the efficiency of the air conditioner, the building type, and the climate, air conditioner savings can equal 10– 30% of the lighting energy savings.
Lighting systems in most commercial buildings operate during the peak period, so a kW of reduced lighting power is also a kW of peak demand reduction. Since air conditioners also generally operate in the peak period, and a more efficient lighting system reduces air conditioner load, additional demand reduction is realized. The additional reduction will depend on the efficiency of the air conditioner but will range between 30–50% of the lighting demand reduction. For electric rates with a demand charge, the monetary savings from an efficient lighting system are the sum of the energy savings and the savings due to demand reduction.
A calculation procedure is presented in Figure Error! Reference source not found. that may be used to estimate both the direct lighting cost savings and the indirect cost savings due to reduced loads on the air conditioner. The calculation considers reductions in both energy use and electric demand. An explanation of the calculation follows the calculation form.
The calculation procedure in Figure Error! Reference source not found. may be used for buildings that have rate schedules where the cost of electricity does not change during the course of a day. Many electric rates for commercial buildings are more
2-34 The Lighting Retrofit Process complex, however, and require that the estimate of kWh and kW be made separately for each time-charge period. With time-of-use rates, it is necessary to divide the electricity energy use into separate bins for each time-charge period. For instance if the utility charges a different rate for electricity used between noon and 6:00 PM, the estimate of annual hours is divided between those hours that occur between noon and 6:00 PM and all other hours. Energy use is separately calculated for each time period and the applicable rate is applied. The procedure in Figure Error! Reference source not found. can be modified to include some of these details.
2-35 The Lighting Retrofit Process
2-36 The Lighting Retrofit Process
Figure 2-4 Calculation Form for Estimating Energy Cost Savings (continued)
2-37 The Lighting Retrofit Process
Table 2-4 Fraction of Annual Lighting Heat to Cooling and Heating
Fraction of Lighting Heat to: Fraction of Lighting Heat to: Location Cool Heat Location Cool Heat Alabama Iowa Birmingham 0.57 0.09 Council Bluffs 0.40 0.32 Huntsville 0.53 0.11 Mason City 0.34 0.39 Mobile 0.66 0.01 Sioux City 0.38 0.36 Montgomery 0.61 0.06 Kansas Arizona Dodge City 0.44 0.26 Flagstaff 0.32 0.37 Goodland 0.41 0.30 Phoenix 0.71 0.00 Kansas City 0.44 0.22 Tucson 0.69 0.02 Wichita 0.47 0.19 Arkansas Kentucky Blytheville 0.51 0.16 Covington 0.42 0.25 Fort Smith 0.53 0.14 Hopkinsville 0.49 0.17 Little Rock 0.54 0.11 Louisville 0.46 0.22 California Louisiana Barstow 0.56 0.10 Alexandria 0.64 0.03 Bishop 0.53 0.15 Lake Charles 0.68 0.02 Los Angeles 0.56 0.00 New Orleans 0.68 0.02 Sacramento 0.49 0.04 Shreveport 0.61 0.05 San Diego 0.52 0.00 Maine San Francisco 0.38 0.02 Portland 0.27 0.36 Santa Barbara 0.21 0.05 Massachusetts Colorado Boston 0.34 0.27 Colorado Springs 0.37 0.29 Springfield 0.35 0.35 Denver 0.39 0.29 Michigan Grand Junction 0.41 0.29 Detroit 0.33 0.31 Trinidad 0.44 0.30 Grand Rapids 0.33 0.35 Delaware Lansing 0.34 0.32 Dover 0.41 0.23 Sault Sainte Marie 0.22 0.41 Wilmington 0.41 0.32 Traverse City 0.29 0.38 Florida Minnesota Miami 0.87 0.00 Duluth 0.22 0.42 Jacksonville 0.72 0.02 International Falls 0.24 0.44 Orlando 0.80 0.00 Minneapolis 0.33 0.39 Pensacola 0.66 0.01 Mississippi Tampa 0.80 0.00 Biloxi 0.65 0.01 Georgia Columbus 0.59 0.10 Atlanta 0.52 0.10 Montana Augusta 0.61 0.08 Billings 0.32 0.36
Macon 0.60 0.06 Glasgow 0.30 0.41 Idaho Great Falls 0.29 0.37 Boise 0.34 0.26 Helena 0.27 0.38 Lewiston 0.33 0.24
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Table 2-9 Fraction of Annual Lighting Heat to Cooling and Heating (continued)
Fraction of Lighting Heat to: Fraction of Lighting Heat to: Location Cool Heat Location Cool Heat Nevada Oregon
Ely 0.35 0.36 Burns 0.30 0.35 Las Vegas 0.61 0.05 Eugene 0.26 0.14 Reno 0.36 0.25 Medford 0.37 0.19 Winnemucca 0.39 0.30 Pendleton 0.35 0.24 New Hampshire Portland 0.27 0.14 Manchester 0.33 0.37 Pennsylvania New Jersey Philadelphia 0.41 0.24 Trenton 0.40 0.28 Pittsburgh 0.38 0.30 New Mexico Scranton 0.35 0.34 Alamogordo 0.56 0.14 Williamsport 0.36 0.31 Albuquerque 0.47 0.20 Rhode Island Clovis 0.51 0.17 Providence 0.32 0.29
New York South Carolina
Albany 0.34 0.35 Charleston 0.62 0.05 Buffalo 0.33 0.34 Columbia 0.58 0.09 Syracuse 0.34 0.35 Myrtle Beach 0.56 0.08 New York City 0.35 0.24 South Dakota
North Carolina Huron 0.35 0.41 Greensboro 0.49 0.16 Rapid City 0.34 0.36 Raleigh 0.52 0.14 Sioux Falls 0.35 0.39 Wilmington 0.58 0.05 Tennessee
North Dakota Knoxville 0.50 0.16 Bismark 0.32 0.42 Memphis 0.53 0.13 Fargo 0.29 0.42 Nashville 0.49 0.14 Grand Forks 0.29 0.42 Texas
Minot 0.28 0.42 Amarillo 0.49 0.19 Ohio Corpus Christi 0.74 0.01 Cincinnati 0.42 0.25 Dallas 0.60 0.07 Cleveland 0.36 0.31 Houston 0.73 0.02 Columbus 0.41 0.27 Lubbock 0.53 0.14 Dayton 0.42 0.29 San Antonio 0.71 0.03 Toledo 0.37 0.33 Utah
Oklahoma Salt Lake City 0.34 0.29 Altus 0.54 0.02 Wendover 0.37 0.29 Enid 0.49 0.16 Vermont
Oklahoma City 0.51 0.17 Burlington 0.29 0.39 Tulsa 0.51 0.17 Virginia
Richmond 0.46 0.16 Roanoke 0.46 0.18
2-39 The Lighting Retrofit Process
Table 2-9 Fraction of Annual Lighting Heat to Cooling and Heating (continued)
Fraction of Lighting Heat to: Fraction of Lighting Heat to: Location Cool Heat Location Cool Heat Washington Wisconsin
Seattle 0.16 0.17 Green Bay 0.30 0.39 Spokane 0.27 0.32 Madison 0.35 0.38 Washington, DC Milwaukee 0.36 0.36
0.45 0.23 Wyoming
West Virginia Casper 0.33 0.37
Charleston 0.45 0.22 Cheyenne 0.32 0.35 Clarksburg 0.39 0.30 Rock Springs 0.29 0.40
Source: Rundquist, R.A., Karl F. Johnson, and Donald J. Aumann. “Calculating Lighting and HVAC Interactions,” ASHRAE Journal, November 1993.
Some rates include "ratchets" that consider the demand history of previous months in calculating billing demand. For these and other more complex rates, you may want to consider the use of computer simulation programs such as DOE-2, PowerDOE, COMTECH or other commercially available programs, which can model more complex thermal interactions and utility rates. With such programs, you will build a more complete model of the building, including building envelope descriptions and HVAC systems. Interactions between heat produced by the lights and air conditioning energy are calculated for each hour based on the thermal loads and internal loads at that hour. This more accurate method requires detailed information about the entire building, not just the lighting systems. Furthermore, hourly schedules of operation are needed, not just FTE hours.
Replacement and Maintenance Costs
In comparing alternative lighting designs, other operating costs, such as lamp and ballast replacement costs and maintenance, should also be considered. Estimates of maintenance and replacement costs can be obtained from maintenance contractors and lamp manufacturers. The most critical factor is usually the estimated lamp life. This can range from 750 hours for some standard incandescent lamps to more than 20,000 hours for some high-intensity discharge lamps. Compact fluorescent lamps usually have a rated life of about 10,000 hours. Lamp life data are provided by manufacturers based on three hours per start for most fluorescent lamps and ten hours per start for HID lamps.
2-40 The Lighting Retrofit Process
Group relamping should be considered in all maintenance programs. Not only can labor costs be reduced, but it is easier to maintain uniform lamp color and brightness. In addition, lamp replacement costs may be lower because lamps can be purchased in volume at a discount. Group relamping can also save energy if lumen maintenance controls are installed. Group relamping can usually be performed in conjunction with fixture cleaning and maintenance, and can be scheduled at times when the building is not in use to prevent disruption of normal operations. Keep this in mind as actual operation time can dramatically affect lamp life, especially with fluorescent lamps.
Economic Analysis
Once all costs are known, the cost-effectiveness of design alternatives should be evaluated. The most common measure of economic performance is simple payback, which is the length of time (in years) that it takes for the energy savings to equal the initial investment. Simple payback is easy to calculate and is understood by most persons, but it has some limitations. For instance, it can only be used to compare two competing alternatives. If more than one alternative is to be evaluated, they must be compared to a single base case. In common usage, simple payback does not take account of differences in maintenance costs or replacement costs that may be imminent.
Other measures of economic performance include net present value (life-cycle cost), internal rate of return, benefit-to-cost ratio, and annualized cost. These concepts are discussed in greater detail in Appendix F. Appendix F also includes present worth tables needed for economic evaluation of alternatives.
Construction and Commissioning Phase
Bid Documents
Engineering is completed with sufficient drawings and/or specifications to allow the installer to accurately determine a price and successfully complete an installation. If the entire process is handled by a single company, such as an ESCO or a lighting contractor, the technical specifications may be minimum, as the "turnkey" supplier generally assumes all risks. However, if independent engineers are preparing contract documents for obtaining bids from competing contractors, complete documentation is absolutely required.
Final engineering drawings and specifications include the kind of information generally not needed during engineering analysis. A retrofit of 2'x 4' lens troffers, for instance, can be studied as if the troffer were "generic." However, in final engineering, the retrofit engineer will find that many of the parts, such as the reflector/socket kit or the lens, must be ordered specifically for the manufacturer, product, and (in some
2-41 The Lighting Retrofit Process cases) the product version or year. If the final engineering documents fail to identify a special problem or condition, such omission could add substantially to the cost of a retrofit and therefore ruin the payback. It is important for the bid documents to include the commissioning tasks expected of the contractor (see below).
A typical example involves lenses. Some office buildings designed in the 60s and 70s employed ceiling systems of non-standard dimensions. Luminaires have been found to have actual dimensions of 27" x 54", instead of 24" x 48". All other factors—lamp, ballast, reflector— are fairly standard. But the lens cost is about 400% of the standard lens. Such an oversight would probably cost the building owner about twice the difference, or about 600% of the lens cost. The net effect would be to raise the project cost about $15 per luminaire, significantly reducing the cost-effectiveness of the measure.
Bidding and/or Negotiation
In this task, a contractor is selected; or if one has already been selected through a separate process, a construction contract is negotiated. Because there are always unique field conditions that escape the notice of the lighting auditors, contractors who blindly follow specifications without caution or flexibility should be avoided. It is advantageous to have a contractor with the skill and experience to recognize unexpected situations and to discover specifications that seem not to make sense in a given space. These areas of work should be temporarily skipped until the specifier/designer is contacted and a decision is made on how to address the problem.
Construction
During construction, the designer or construction manager should work closely with the occupants to explain the purpose of the retrofit and to schedule access. This can be a very time-consuming task, especially when there are areas that have security access restrictions or that contain delicate apparatus that may be damaged by construction crews. The designer or construction manager should also work closely with the contractor(s). Field conditions will frequently differ from those specified in the contract, and decisions will often need to be made to modify the specifications for non- conforming areas.
Lamp and Ballast Disposal
Relamping as a retrofit strategy introduces the problem of what to do about the disposal of old lamps. Fluorescent and HID lamps, for example, contain small amounts of mercury. Although the Environmental Protection Agency currently has no restrictions covering the disposal of lamps, this is expected to change. Some states, such as California, regulate the quantity of fluorescent lamps that may be disposed of at one 2-42 The Lighting Retrofit Process time. The retrofitter is responsible for learning of any federal, state, or local regulations regarding the disposal of old lamps and/or ballasts. In case of doubt, fluorescent lamps should be disposed of through a company licensed to dispose of fluorescent lamps or mercury products. Most HID lamps also contain mercury and require similar disposal precautions.
You should identify a licensed disposal company in your area and obtain costs to use in the analysis. The following costs are fairly typical for 1996. Full-size fluorescent lamp disposal costs range from $0.06 to $0.10 per foot ($0.24 to $0.40 for a four-foot tube). Ballast disposal costs depend on whether or not the ballasts have PCBs. The cost to dispose of non-PCB ballasts ranges between $0.30 and $0.40 per pound, while the cost to dispose of PCB ballasts ranges between $0.45 and $0.60 per pound. A typical two- lamp F40 ballast weighs about 3.5 lb. while a typical two-lamp F96 ballast weighs about 7.0 lb.
Asbestos
Ceilings employing asbestos or building structures fireproofed with asbestos limit the possibilities for the retrofitter because of the great cost of properly handling airborne asbestos fibers. Most of the time, all modifications will be made from below the luminaire without moving the luminaire from its grid location. If asbestos is not present, the retrofitter should also consider modifying the lighting layout as many older lighting designs had more luminaires than modern practice recommends.
Commissioning
Once the full audit is complete and retrofit options are selected and installed, it is extremely critical that the new components be calibrated and maintained properly. Occupancy sensors and dimmers are especially likely to perform under par if incorrectly installed or calibrated.
Furthermore, if building engineers do not understand the new system they may find ways to override or mis-calibrate it. The project’s energy savings and quality would not then reach the expected potential. Training programs for building operating personnel are an essential part of a good commissioning plan. In addition, lighting maintenance crews must become familiar with the new products installed and be alerted to the warranty procedures for products that may subsequently fail.
Verification and Measurement
Once the retrofit measures are installed, measurement is often required on a periodic basis to assure that the predicted savings are being achieved.
2-43 The Lighting Retrofit Process
Verification of savings will find flaws in the predictions of the engineers. In many buildings, for instance, the heat of the lighting system is used to heat the building. Of course, mechanical heating (such as a furnace) is much more efficient, but in older lighting technology, heat was a side benefit. There have been several lighting retrofits where the designer forgot to check on the heating capacity of the HVAC system and, as part of the retrofit, to add heating capacity. The net result of this type of error is that increased heating costs erode the lighting savings. If employees respond by installing portable resistance space heaters, then the electric bill including demand charges may actually go up. The theoretical lighting and HVAC savings are not achieved because the system lacks the heating capacity to prevent the employees' actions.
Ongoing operations of a building complicate matters. Changes in building occupancy, hours of operation, and process or office equipment can dramatically change the building load. Without proper precautions, measurements can suggest lighting retrofit results far different from actual occurrence.
In order to create an effective lighting verification program, the following steps are recommended: x Establish an accurate baseline. The baseline is critical. As accurately as possible, establish annual operating hours for every different schedule in the building. Measure only lighting loads whenever possible, avoiding especially receptacle and process load circuits. Measure unit loads to help make calculations more accurate. Account for burnouts and deferred maintenance as an adjustment to measured values. Measure kWh and kW over as long and representative a period as possible. Account for seasonal variations as a further adjustment after measurements. Wherever possible, determine operating time using run time or time-of-use lighting loggers. x Establish a reasonable means to account for HVAC savings. For each unit of lighting energy savings, a building that is air conditioned will typically experience an additional 10–30% of energy savings due to reduced loads on the HVAC system. These savings will be hard to measure and verify, since weather is the primary variable and obviously not repeatable for a monitoring period from year-to-year. To account accurately for HVAC savings, install long-term measurement equipment on HVAC equipment, and collect annual data to document before-and-after performance. x Verify lighting load changes as directly as possible. Immediately upon completion of the retrofit, measure lighting loads. Emphasize changes in adjusted kW demand for luminaire retrofit projects and kW demand and kWh for controls retrofits. Take extreme care that future measurements are taken for the same building area and at the same point. Many buildings have 277/480 volt lighting systems and 120/208 volt general receptacle and power systems, making this easier for the general illumination fluorescent and HID systems; 120-volt lighting (usually incandescent)
2-44 The Lighting Retrofit Process
is usually on independent circuits from plug load and other 120-volt loads. Of course, many projects (especially smaller ones) will have mixed loads on the branch circuits. In these cases, it is important to make certain that all loads have been identified and their presence (or absence) recorded during each measurement. x Account for ongoing changes in the building's operation and occupancy. Surprisingly, this can be quite easy. If floor plans were obtained or available during design, keep track of building plan changes. New walls or new tenants should be identified on the plans on an ongoing basis. If plans were not obtained or developed, make film or video records of the building and compare, if necessary, to the owner's records of tenancy changes in the event of a dispute. Note that construction can consume significant energy, and lights can get turned on even in unoccupied areas of the building. Operating hours can be remeasured with loggers if it appears a significant change occurred. x Visually inspect for changes and "snap-back." Lighting different from the retrofit program will stand out and should be easy to identify. Although snap-back is a sign of a problem in acceptance or retrofit maintenance cost, make a fair provision in the verification program to account for it. x Use each measurement program as a conservation study. Many times, additional opportunities will become obvious during a follow-up review for measurement/verification. Some opportunities not previously economically viable will become worthwhile due to changes in operations, utility rate, and/or rebates.
Measured field data, in addition to the audit estimates, are an often overlooked yet extremely critical component of an accurate retrofit analysis. Using only the common estimating techniques, errors as great as 25–40% of potential savings occur, usually due to three problems. First, the energy actually used by a fluorescent system can differ by 5–25% from the energy use figures that appear in manufacturers’ catalogues. Second, the actual hours that lighting systems operate are usually quite different from simplified assumptions. And third, the impact of the lighting load on the HVAC system is often estimated incorrectly or completely omitted from the analysis.
Ongoing Maintenance
After a lighting retrofit, maintenance is almost eliminated for quite a while, saving the owner considerable expense. After that, proper maintenance of the lighting is essential in preserving the energy efficiency of the lighting. Otherwise, lighting will be added or modified in a manner unintended by the engineers and often to the point of ruining the energy savings.
A term describing the most common undesirable phenomenon after the retrofit is snap- back, meaning that the installation will "snap back" to the previous condition. Snap-back is best prevented by using technologies which cannot easily be returned to the original
2-45 The Lighting Retrofit Process condition. For example, screw-in compact fluorescent lamps are generally not recommended for commercial installations because after the life of the lamp or adapter (usually about 8,000 hours, or 1–2 years in commercial applications), the operator of the facility will be forced to choose between a lower cost replacement (incandescent) and replacing the aged fluorescent. Since this person often was not part of the original decision, he or she will be ill-informed of the benefits of compact fluorescent and enticed by the low cost of incandescent. Snap-back is virtually inevitable.
By following through with service and maintenance, the retrofitter helps prevent snap- back and other problems, such as: x unnecessary or unwise expansion of track lighting systems x use of higher-wattage replacement lamps x use of lower-efficiency magnetic ballasts when electronic ballasts fail x changes in operations resulting in greater energy cost x minimizing maintenance errors, e.g. purchasing F40 lamps for replacement of T-8 systems, encouraged by lower product cost and purchaser ignorance x energy waste due to improperly installed, adjusted, or commissioned lighting and lighting controls
Other practical concerns are that the storehouse be alerted to begin eliminating outmoded products and stocking new equipment, and that electricians receive as-built drawings of areas with automatic lighting controls so that they do not waste time trouble shooting a circuit that is open due to control malfunction.
2-46 3 RETROFIT TECHNOLOGIES
This chapter of the handbook outlines some of the most important technology changes that can be incorporated in any lighting retrofit. Many of these technologies can be used as simple unit replacements for failed or retired equipment or components, while others must be carefully planned and incorporated into a thoughtful lighting retrofit strategy. Information in this chapter is organized in three sections: lamp/ballast technologies, luminaire technologies and control technologies. Chapter 4, Lighting System Types, looks at retrofit opportunities as they relate to lighting system types. For instance, the retrofit opportunities for commercial troffers, a distinct lighting system type, are discussed. This chapter, on the other hand, presents generic information about the basic technologies that may apply to more than one lighting system type such as switching from T-12 fluorescents to the newer T-8 technology with electronic ballasts.
Lamp/Ballast Technologies
In the past five to ten years, lamp and ballast manufacturers have steadily improved the quality of their products, while introducing several successful new lamp technologies. Many of these products are targeted for the retrofit market; as such, they are designed to be energy-efficient alternatives to existing products. Most of these products improve overall lighting quality as well as energy efficiency. Often these new lamps can replace existing, less efficient lamps on a simple socket for socket basis, with minimal labor charges for the relamping (though some strategies require a change in ballasts, sockets or luminaires to accommodate the new lamps). Many effective relamping situations require no change in building wiring and no replacement of luminaires or ballasts. Similarly, relamping does not create any significant new maintenance issues other than that new lamp types must be purchased and warehoused. As such, relamping can be a simple, effective, and cost-conscious retrofitting strategy. The important lamp technologies for the retrofit market are briefly described in the following sections.
Relamping Retrofit Opportunities
This section presents some general considerations for relamping of existing lighting equipment. More details on each lamp ballast technology are presented in the sections that follow. In general, relamping as a retrofit strategy should be limited to applications when one or more of the following situations exists:
3-1 Retrofit Technologies x There is a significant opportunity to save energy by using more efficacious lamps and by lowering HVAC costs. x There is a need to increase the illuminance produced by a lighting system through the use of more efficient lamps and/or luminaires. x There is an opportunity to reduce lighting levels. x There are opportunities to replace existing lamps with products requiring less maintenance due to a longer effective operating lifetime. x There is a desire or need to improve lighting quality through the use of lamps that improve color temperature and color rendering. x There is a need to use new lamp technologies because of the provisions of the Federal Energy Policy Act or other standards or regulations.
Most relamping retrofit applications are fairly simple and straightforward: once the retrofitter has determined that relamping is an appropriate strategy to pursue, he (she) looks to increase the efficacy and lighting quality of the situation at hand. This goal must be factored with the overall dollar amount of the cost premiums to be paid for the relamping and with the length of the payback period. Most relamping strategies have a payback period of less than three years, making relamping a very attractive retrofit lighting strategy. The following table illustrates some common lighting problems that can be resolved with appropriate relamping strategies:
Table 3-1 Common Relamping Strategies
Situation Relamping Remedies
Correct Illumination Relamp with more efficacious light sources (e.g. replace incandescent lamps with compact fluorescents)
Delamp (use reflectors, higher-output lamps, or higher-output ballasts to compensate for lost output)
Overlighted Spaces Delamp (Relamp with higher-output lamps if light levels are reduced too much)
Relamp with lower-output lamps
Underlighted Spaces Relamp with higher-output lamps, use reflectors, use higher-output ballasts
Excessive Lamp Failure Costs Relamp with longer-life lamps
Poor Lighting Quality—Color Rendition Relamp with high CRI sources
Poor Lighting Quality—Glare Usually not an appropriate option
3-2 Retrofit Technologies
Table 3-2 Relamping Options
Existing Lamp Applications Appropriate Replacement(s) Performance Benefits
Incandescent "A" General & Down Lighting Compact Fluorescent Efficacy & Lamp Life Metal Halide Efficiency, Efficacy, & Lamp Life
Incandescent Reflector Wall & Down Lighting Compact Fluorescent Efficacy & Lamp Life Halogen PAR Efficiency & Efficacy
Incandescent Reflector Display Lighting Halogen IR Efficiency & Efficacy Compact Metal Halide* Efficiency, Efficacy, & Lamp Life; Fewer Fixtures Required
F40T12 (Standard) General Lighting 32-34-watt F40T12/ES Efficiency F40T12/RE Efficiency, Efficacy, & CRI F40T10 Efficiency, Efficacy, & CRI F32T8* Efficacy & CRI
*Requires replacement luminaire socket and/or ballast
In most relamping retrofit strategies, the retrofitter will have more than one lamp option that will serve the purpose. There are at least two considerations that should be examined in determining the retrofit lamp to choose. First, the ideal lamp replacement will enhance lighting system performance on as many levels as possible (efficacy, CRI, lamp life, etc.). For instance, a lamp that provides both increased efficacy and longer life may be a more desirable alternative than one which only increases efficacy. Table 3- shows some of the more common relamping options.
Another factor that the prudent retrofitter must consider when choosing among different relamping options is the relative payback periods of different relamping options. An expensive relamping strategy that requires 5–7 years to recapture the initial cost premium will probably not be as desirable as a relamping scheme that actually saves less energy, but pays for itself in under three years.
Lamp Performance Measures
There are several measures of lamp performance, including energy efficiency or efficacy, lamp life, lamp lumen depreciation (LLD), and color, that are important in making retrofit decisions that involve lamp replacements. In general, relamping strategies should substitute lamps that have better performance than the lamps they replace in as many areas as possible. Table 3- shows the typical performance of different types of lamps. More detail is provided in the text that follows.
3-3 Retrofit Technologies
Table 3-3 Performance Characteristics of Various Light Sources
Lamp Type Efficacy* Average Life (Hours) Lamp Lumen Correlated Color Color (Lumens/ Watt) Depreciation Temperature Rendering (LLD) (CCT) (°K) Index (CRI)
Standard Incandescent 5–20 750–3,000 High 2,800 100
Tungsten Halogen 15–30 2,000–4,000 Low 3,000 100
Halogen Infrared Reflecting 20–30 2,000–3,000 Low 3,000 100
Mercury Vapor 30–60 12,000–24,000 High 3,300–5,700 15–50
Compact Fluorescent (5–26 Watts) 20–85 9,000–12,000 Low 2,700–5,000 80
Compact Fluorescent (27–40 Watts) 50–80 15,000–20,000 Low 2,700–5,000 80
Full–Size Fluorescent 60–90 15,000–24,000 Medium 2,700–7,500 50–90
Metal Halide (175–1500 Watts) 45–100 3,000–20,000 High 3,000–6,500 65–85
Compact Metal Halide (32–150 Watts) 45–80 2,000–20,000 High 3,200–6,500 60-90
High Pressure Sodium 45–130 16,000–24,000 Low 2,100–2,200 22
Deluxe and White Sodium 35–55 10,000–15,000 Medium to High 2,200–2,800 65–80+
*Note: Lumens per watt values include ballast; all values are for most commonly used lamps and are approximate. See the 1993 Advanced Lighting Guidelines for specific values.
Figure 3-1 Lighting Source Efficacies
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Energy Efficiency
Efficacy is the common term for the energy efficiency of lamps. Efficacy is the ratio of the light produced by the lamp (in lumens) to the rate of energy used by the lamp (in watts). The least efficacious lamps have an efficacy of less than 10 lumens/watt, while the most efficient lamps have an efficacy of more than 100 lumens/watt. The efficacy range can be quite large for a particular lamp type depending on its size (wattage), the type of ballast and other features. Data on typical lamp efficacies are presented in Table 3-. Figure 3-1 shows the typical range for each lamp type.
In addition to producing visible light, lamps produce heat. High efficacy lamps produce less heat than the less energy-efficient products they replace. In some cases, this heat production is quite extreme. Some incandescent lamps, for instance, convert up to 90% of the power they receive into heat. Less than 10% of the input power is converted to visible light. Efficacious lamps are able to reduce this ratio considerably, contributing to significantly reduced air conditioning loads and more comfortable conditions.
When determining the efficacy of any lamp under consideration for retrofitting, it is important to include consideration of the ballast and the luminaire. The ballast is an integral part of the source system that cannot be ignored. The effect of the luminaire is more subtle and fluorescent luminaire performance is related to the bulb-wall temperature of the lamps. Closed luminaires (those with lenses) operate at a higher temperature than open luminaires (those with open parabolic reflectors). Similarly, four-lamp troffers operate at a higher temperature than two-lamp troffers. In general, the higher the temperature, the less efficient the lamp; but this is not always true. For more information, see the chapter on luminaires and lighting systems in the 1993 Advanced Lighting Guidelines, TR# 101022, R1 available from EPRI. Incandescent and HID luminaire performance is not affected by ambient temperature.
Lamp Life
Lamp life (in hours of operation) is another measure of performance. Lamp life ratings are determined under ANSI conditions (open air, 25°C [77°F]) at three operating hours per start for fluorescent and 10 hours of operation per start for HID lamps. Effective lamp life may be adversely affected by more frequent switching. Similarly, rated lamp life is generally increased by average operating times of more than three hours per start. Maintenance costs for relamping are reduced by employing lamps with long operating lives. As such, the ideal retrofit relamping strategy would provide products with extended operating lives whenever possible. See Table 3- for typical lamp lives.
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Lamp Lumen Depreciation (LLD)
The light output of most light sources decreases with accumulated hours of operation. Thus, lamps that are near the end of their lives may produce significantly less light than new lamps. Different lamp technologies have significantly different rates of lumen depreciation. For instance, standard incandescent lamps depreciate noticeably as they age, due to a gradual boiling away of the tungsten filament. Filament particles eventually deposit on the lamp’s bulb wall, effectively blocking much of the lamp's lumen output, which has already been reduced due to the smaller diameter of the filament. Modern tungsten halogen lamps, by contrast, show very little lumen depreciation over lamp life, as their design is such that evaporated tungsten molecules are caused to redeposit onto the lamp filament. Lamp lumen depreciation for some high intensity discharge (HID) lamps is considerable, as much as 50%. Consideration of the extreme LLD of these HID lamps can result in recommendations to replace the source with fluorescent. Even though the fluorescent lamp may be less efficacious in terms of initial lumens, it is a more efficient source for the life of the lamp.
Color Rendering Index (CRI)
The color rendering index (CRI) of a lamp describes the degree of color shift that objects undergo when illuminated by the light source under consideration, as compared to their color appearance under a reference source of the same color temperature. CRI is measured on a scale up to 100. Incandescent lamps are the reference (below 5000K) and have a CRI of 100 (by definition). For lamps with color temperatures above 5000K, daylight is reference and has a CRI of 100 (by definition). The CRI for standard halophosphor fluorescent lamps is substantially lower (typically, around 55–60). Table 3- gives a CRI range for common lamp types while Table 3- shows the typical CRI range and gives some examples of lamps in each range. Many of the energy-efficient advances in lamp technologies have also improved color rendering. As a result, most retrofits will not only improve energy efficiency, they will also improve the lamp’s color rendering ability.
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Table 3-4 Color Rendering
Lamp Quality Color Rendering Index
High-Pressure Sodium Poor 22
Deluxe Mercury Vapor Poor 50
Warm White Fluorescent Fair 53
Cool White Fluorescent Fair 62
Clear Metal Halide Fair 65
Rare Earth Fluorescent Good–Excellent 70–85
Deluxe Metal Halide Excellent 80–90
Special Fluorescent Excellent 92
Incandescent or Sunlight Reference 100
Table 3-5 Color Temperature
Correlated Color Temperature Lamp Types Ambiance
2100 K High-pressure sodium Very warm
2500–3200 K Incandescents Warm Warm fluorescents
3400–4300 K Cool and white fluorescent Neutral to cool Most metal halides
4500–7500 K “Daylight” fluorescent Cool to blue Cool metal halide
Correlated Color Temperature (CCT)
The correlated color temperature (CCT) of a light source is the apparent color of light produced by that source. CCT is measured in Kelvins (K). Technically, the CCT is the temperature of a black body radiator that has the same apparent color. Most electric lamps produce light with a CCT between about 2000K and 8000K. In an odd play of terminology, lower temperatures produce a warmer ambiance and higher temperatures produce a cooler ambiance. Table 3-5 illustrates the range of color temperatures and gives examples of lamps that operate in each range. Lamps with temperatures of 4100K and above produce a light that is bluish-white in appearance (cool), while lamps with temperatures of 3000K and below produce a warmer light. For further information, consult The Lighting Fundamentals Handbook, TR-101710 available from EPRI.
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With efficacy, color rendering index, and lamp life, more is always better. This is not the case, however, with color temperature. Sensitive designers will carefully select the color temperature of lamps to create the desired ambiance and mood. Sometimes a warm ambiance is desired, for instance in hotel lobbies. Sometimes a cool ambiance is desired, for instance in manufacturing plants. The development of energy-efficient lamp technologies has expanded the designers’ capabilities by extending the color temperature range of most lamps.
Lamp Efficiency and Energy Legislation
The Energy Policy Act of 1992 was passed by the 102nd Congress and signed into law by former President Bush on October 24, 1992. The Act is an amendment to the 1975 Federal Energy Policy and Conservation Act, and has profound implications for the lighting retrofit market. The Act establishes minimum efficiency standards for many types of electric lamps. Targeted lamps not meeting required efficiency standards cannot be manufactured or imported for sale in the United States. The Energy Policy Act also calls for lamp labeling. Lamps will be labeled so that users may choose the most energy-efficient lamps available.
Efficiency Standards
The current provisions of the 1992 Energy Policy Act assign efficiency standards to popular versions of full-sized fluorescent and R and PAR-type incandescent reflector lamps. The Act may be amended at a later date to extend the standards to other lamp technologies and configurations.
Table 3-6 Energy Policy Act Requirements for Full-Size Fluorescent Lamps
Lamp Type Nominal Minimum Minimum Average Lamp CRI Efficacy (LPW) Wattage 4-foot Med. Bi-Pin !35 69 75.0 d35 45 75.0 2-foot U-shaped !35 69 68.0 d35 45 64.0 8-foot Slimline 65 69 80.0 d65 45 80.0 8-foot High Output !100 69 80.0 d100 45 80.0
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Table 3-7 Energy Policy Act Requirements for Incandescent Reflector Lamps
Nominal Lamp Wattage Minimum Average Efficacy (LPW) 40–50 10.5 51–66 11.0 67–85 12.5 86–115 14.0 116–155 14.5 156–205 15.0
Full-Size Fluorescent Lamps. The Energy Policy Act is having a profound effect on the use of full-size fluorescent lamps. Lamp efficiency standards apply to the most common lamps used in commercial output lamps. To comply with the efficiency standards, lamps must meet the minimum efficacy and CRI values shown in the table.
The most significant effect of the Energy Policy Act on fluorescent lamps is that it will eliminate the manufacture and importation of most full-wattage (non-energy saving) halophosphor cool white and warm white lamps. This will encourage the use of high- CRI RE lamps, producing significant improvements in energy efficiency and lighting quality in standard commercial lighting installations.
Fluorescent lamps exempt from the efficiency standards of the Energy Policy Act include colored lamps, ultraviolet, high-CRI halophosphor, cold temperature, and plant growth lamps. The efficiency standards took effect April 30, 1994, for 8-foot lamps and October 31, 1995, for 4-foot and U-shaped lamps.
Incandescent Reflector Lamps. Lamp efficiency standards of the Energy Policy Act will also apply to medium-based incandescent R and PAR-type reflector lamps, 115–130 volt, 40–205 watts, with a diameter greater than 2¾" (R/PAR-22). The standard for these lamps became effective October 31, 1995, and it is likely to eliminate the use of many non-halogen incandescent R and PAR lamps. Reflector lamps that will be exempt from compliance include ER (elliptical reflector) lamps, colored lamps, rough service lamps, and R20/PAR20 lamps. Non-exempt incandescent reflector lamps must meet minimum efficacy levels, relative to lamp wattage, as listed.
The new efficiency standards for R and PAR-shaped incandescent reflector lamps will effectively eliminate the manufacture and importation of a large number of extremely popular lamps. Specific examples include R-30 and R-40 reflectors as well as all non- halogen PAR-38 lamps. “BR” lamps are exempt, and some classic designs are reincarnated as more efficacious, shorter-life types.
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Lamp Efficiency Labeling
The Energy Policy Act of 1992 also requires that the Federal Trade Commission (FTC) establish lamp labeling rules that will allow users to select the most energy-efficient lamps that meet their respective application requirements. There are four lamp categories that are affected: x medium-based general service incandescent lamps, 115–130 volts, 30 watts and above x R and PAR incandescent reflector lamps 115–130 volts, 40 watts and above, larger than R-22 (2¾") in diameter x medium-based (self-ballasted) compact fluorescent lamps x full-size T-8 and T-12 fluorescent lamps
There are several products in each category that are exempt from the labeling requirements. Most of the exempted lamps are decorative or serve a special purpose.
Additional Requirements
The U. S. Department of Energy (DOE) will be in charge of evaluating the new efficiency standards for fluorescent and incandescent reflector lamps. DOE will determine if these standards should be amended. The Energy Policy Act also directs DOE to examine the feasibility of establishing efficiency standards for HID lamps. In addition, DOE is charged with evaluating the need for efficiency standards for other lamp types not covered by the Act. In addition to standards on lamps and ballasts, the Energy Policy Act requires that states update their building energy efficiency standards to be at least as stringent as ASHRAE/IESNA Standard 90.1—1989.
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Figure 3-2 Tungsten Halogen Lamp Sizes
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Tungsten Halogen Lamps
Though only slightly more efficacious than standard incandescent lamps, tungsten halogen lamps are nonetheless valuable, inexpensive retrofitting options for many incandescent applications. These lamps are filled with a halogen gas that suppresses degradation of the tungsten filament. Lamp design allows for filament configurations that produce a brilliant white light with higher efficacy and longer life than traditional incandescent lamps.
In most cases, lamps replace standard incandescent lamps without a change in wiring or lamp socket. Ideally, they should be used only in situations where a change to a more efficacious lamp technology (such as fluorescent) would adversely affect design goals. Appropriate applications for lamps might include highlighting of art work, display lighting for merchandising, or other cases where a point source of illumination with full-range dimming and high color rendering is required. Tungsten halogen lamps are available in several configurations. Two of the most important for retrofit applications are described below:
PAR Capsule Lamps
PAR capsule lamps consist of a halogen "bud" surrounded by an outer PAR (parabolic aluminized reflector) envelope. Configurations include PAR-16, PAR-20, PAR-30, and PAR-38. These lamps are designed for accent lighting applications, such as display lighting of merchandise. They can replace standard reflector lamps with a significant reduction in lamp wattage. Nevertheless, they are only slightly more efficacious than standard incandescent lamps.
Infrared-Reflecting Lamps
Infrared-reflecting (IR) lamps have ushered in a new era in retail display lighting. A 60- watt PAR IR lamp can replace a 150-watt standard PAR incandescent lamp, with no loss in illuminance level or lighting quality. IR lamps are especially suitable as retrofit replacements for incandescent track and recessed down lighting. While they still are not nearly as efficacious as other advanced lamp technologies, they do allow for significant reductions in lighting power in retrofit applications. They are available in medium-based PAR envelopes, as well as double-ended, high-wattage quartz lamps.
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Figure 3-3 Infrared-Reflecting Technology
Compact Fluorescent Lamps
Compact fluorescent lamps were originally designed as an energy-efficient retrofit alternative to standard incandescent lamps. Generally, compact fluorescent lamps consume only one-third to one-fourth the energy of their incandescent counterparts, and they last up to 10 times longer. Many are equipped with screw-in, medium-base socket adapters that enable a direct lamp-for-lamp replacement in existing incandescent luminaires. Compact fluorescent lamps are available in several shapes and sizes, including twin-tube, quad-tube, and multiple-tube configurations. Wattages generally range from 5 to 27.
There are two basic compact fluorescent lamp-ballast configurations that are especially applicable for retrofit situations: x Medium-base self-ballasted screw-in compact fluorescent lamps are designed to replace existing incandescent lamps on a socket-by-socket basis. Integral self-ballasted lamps are one piece lamp-ballast units. They are increasingly available with electronic ballasts. These units require that the ballast be replaced along with the lamp when relamping. Modular self-ballasted compact fluorescent lamps, on the other hand, feature a lamp that detaches from the screw-in ballast, allowing for simple replacement of only the lamp at relamping time.
3-13 Retrofit Technologies x Dedicated compact fluorescent units are designed for permanent retrofitting of existing incandescent luminaires. Typically they consist of a hardwire conversion unit, ballast, and single or double socket with detachable lamp(s). They can be designed to use nearly any lamp configuration. Once installed, they allow for simple lamp replacement exclusive of the ballast.
Figure 3-4 Typical Screw-In Compact Fluorescent Lamps
Self-ballasted compact fluorescent lamps are readily available with electronic ballasts. Both the twin-tube and quad-tube compact fluorescent lamps are now available with single-ended four-pin bases, which allow for the removal of the integral starter and facilitates their use with rapid-start electronic ballasts. This is a promising development, as the use of these lamps with electronic ballasts should result in even greater energy efficiency while increasing occupant satisfaction by reducing noise, starting time, and lamp flicker.
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In the past, many electronic ballasts for compact fluorescents have introduced unacceptably high levels of total harmonic distortion (THD) into building power systems. The situation is improving, but the retrofitter should nevertheless try to avoid the use of products with high THD. THD is reported in most literature provided by lamp manufacturers.
Figure 3-5 Typical Dedicated Compact Fluorescent Lamps
The socket adapters included in self-ballasted compact fluorescent lamp packages allow for easy and inexpensive relamping of incandescent luminaires. As a result, compact fluorescent lamps have enjoyed popularity as an incandescent retrofit in everything from recessed down lights to floor and table lamps. Nevertheless, this type of perfunctory retrofit strategy has severe limitations. x First, in retrofit applications, the problem with any screw-in compact fluorescent adapter is that it is not a permanent conversion. Relamping with incandescent lamps at lamp maintenance intervals is a distinct possibility. x Another common problem produced by the use of compact fluorescent lamp packages is that the screw-in lamp-ballast assemblies often are incompatible with the existing design of the luminaires being retrofitted. The result is that luminaire photometrics are compromised, and the overall appearance of the luminaire may be objectionable.
Fortunately, some manufacturers are now offering compact fluorescent products designed to make the conversion from incandescent to compact fluorescent much more permanent and more congruent with luminaire design. Some of these products use
3-15 Retrofit Technologies adapters with added reflectors to improve photometrics, while others are hardwired directly into the luminaire itself.
Figure 3-6 Typical Compact Fluorescent Conversion Kit
Overall, compact fluorescent lamps offer substantial energy savings over traditional incandescent lamps. Replacement of incandescent lamps with equivalent output compact fluorescents can produce energy savings of 60% to 75% and increase lamp life by a factor of 10.
Full-Size Fluorescent Lamps
During the past ten years lamp manufacturers have substantially improved the performance characteristics of full-size fluorescent lamps. The use of high output, high color-rendering rare earth (RE) phosphors along with the development and manufacture of T-8, T-10 and T-5 twin-tube lamp envelopes has increased the opportunities for increased energy efficiency and lighting quality in retrofit lighting design. Several energy-efficient lamp products are now available that allow for the retrofitting of standard F40T12 lamps with more advanced products.
Direct Retrofits for F40T12 Halophosphor Lamps
The following full-size fluorescent lamps may be used to retrofit standard F40T12 lamps on a lamp-for-lamp basis (no change in ballast is required). All of these lamps will provide better energy efficiency, and most will improve color rendering. In addition, most of these lamps have less lamp lumen depreciation and may have extended lamp life.
3-16 Retrofit Technologies x Rare earth phosphor (RE) T-12 lamps utilize rare earth phosphors to produce up to 5% more light and increase CRI substantially over standard T-12 lamps. Rare earth phosphors are now available for virtually every type of fluorescent lamp, including U-Bent lamps. The RE phosphor coating is standard in all advanced products, such as compact fluorescents, T-10s and T-8s. x T-10 lamps also utilize rare earth phosphors. While they draw more power than standard F40 lamps (42 watts to 40 watts), they also increase lumen output by 21%, lamp life by 20%, and color rendering by 42%. They are especially appropriate in applications where a standard T-12 delamping strategy might reduce light levels too much. For example, a four-lamp T-12 fixture can in many cases be retrofitted with two or three F40T10 lamps without too great a drop in overall luminaire output. T- 10 lamps are also useful in many applications where task areas are severely underlighted. They allow for a significant increase in lumen output without the need for new luminaires or ballasts. x Extended output T-12 lamps are also valuable in delamping strategies and underlighted applications. They generate 7–9% more light output and increase lamp life 20% over standard F40 lamps. x Energy saving (ES) lamps draw less wattage than full light output T-12 lamps. ES lamps are available in F40, and F96 slimline and high output configurations and with RE or standard halophosphors. Since ES lamps produce fewer lumens than standard T-12 lamps, their best retrofit application is in overlighted spaces. ES lamps should not be used for dimming applications, and they are more sensitive to lower temperatures than standard T-12 lamps. x Heater cutout lamps are ES lamps that save an additional 2½ watts by disconnecting the lamp heater filament after the initial starting discharge (there are also ballasts that perform this operation). Their performance is similar to that of ES lamps, and the same restrictions apply.
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Figure 3-7 Typical Diameters of Full-Sized Fluorescent Lamps
Lamps
Other advanced fluorescent lamp products have substantially increased performance characteristics when compared with standard T-12 lamps. Not all of these products are practical for most retrofitting purposes, however, since they will require—at the very least—a change in ballasts. Some of these products, such as T-5 twin-tube lamps, also require changing lamp sockets or luminaires, as well, effectively eliminating them from most retrofitting strategies. For these reasons, this discussion is limited to a description of T-8 265 mA lamps.
T-8 lamps operate at 265 mA current. As such, they require special ballasts, though their bases (bi-pin or slimline) will fit the same sockets as corresponding T-12 lamps. These lamps are available in U-bent configurations and in straight tubes up to 8 feet long. Wattages range from 16 to 59.
A 4-foot F32T8 produces nearly the same initial lamp lumens as a standard F40T12, but draws only 32 watts (not including ballast). F32 lamps may be linked with instant-start electronic ballasts to achieve an efficacy of nearly 90 lumens per watt. By comparison, the maximum efficacy of an electronically-ballasted F40T12 system is less than 80 lumens per watt.
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The newest members of the T-8 lamp family are the F96T8 single pin lamp, introduced in 1992 and the F96T8/HO introduced in 1994. They are designed for electronic ballast operation and will compete with the popular F96T12 slimline lamps. The T-8 lamp produces similar light output as the energy savings version of the T-12 counterpart, but system efficacy increases to more than 90 lumens per watt. In addition, electronically- ballasted F96T8 and F96T8/HO lamps have a rated lamp life of 15,000 hours at 3 hours/start. Most of the improved performance is attributed to the use of electronic ballasts.
T-8 lamps are smaller in diameter than traditional T-12 lamps (1" to 1½"), and can be used in smaller luminaire enclosures. In addition, the small size of the T-8 lamp often serves to increase luminaire efficiency due to lower light loss factors.
T-8 lamps generally make good sense in most retrofit applications where a change in the existing ballasts is also being considered. On a life-cycle cost basis, the T-8 lamp- ballast system is generally a better investment than any T-12 system, particularly if electronic ballasts are also installed. However, if the existing ballasts are the energy- efficient type in good condition, it can be a more cost-effective strategy to relamp with energy-efficient T-12 or T-10 lamps if utility rates are low.
A comparison of advanced technology full-size fluorescent lamp characteristics is listed as follows.
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Table 3-8 Fluorescent Lamp Characteristics—Common 4-foot lamps1
Lamp Type Input watts for 2 lamps and Lumen output for a Efficacy CRI ballast pair of lamps (lumens per watt) F40T12CW (pre-1995) (Mag Std) 92 5,612 61 62 40 watt (Mag EE) 86 5,612 65 3050 lumens (Elec RS) 78 5,307 68 F40T12RE70 (Mag Std) 92 5,796 63 724 40 watt (Mag EE) 86 5,796 67 3200 lumens (Elec RS) 80 5,481 70 F40T12RE80 (Mag Std) 92 5,980 65 82 40 watt (Mag EE) 86 5,980 69 3300 lumens (Elec RS) 80 5,655 72 F40T12/ES/CW (Mag Std) 80 4,915 61 62 34 watt (Mag EE) 72 4,915 68 2700 lumens (Elec RS) 682 4,802 71 F40T12/ES/RE70 (Mag Std) 80 5,092 63 724 34 watt (Mag EE) 72 5,092 71 2800 lumens (Elec RS) 68 4,975 74 F40T12/ES/RE80 (Mag Std) 80 5,272 66 824 34 watt (Mag EE) 72 5,272 73 2900 lumens (Elec RS) 682 5,151 76 F40T10/RE80 (Mag Std) 94 6,808 72 85 40 watt (rated) 42 watt (actual) (Mag EE) 88 6,808 77 3700 lumens (Elec RS) 80 6,475 81 F40T12/ES+/RE70 (Mag Std) 76 4,888 64 724 32 watt (Mag EE) 86 4,888 72 2650 lumen F32T8/RE70 (Mag EE) 70 5,270 75 75 32 watt (Mag HC) 66 5,270 76 2800 lumens (Elec RS) 62 5,175 83 (Elec IS) 59 5,155 87 F32T8/RE80 (Mag EE) 70 5,428 77 824 32 watt (Mag HC) 66 5,210 79 2950 lumens (Elec RS) 62 5,332 86 (Elec RS—High output) 84 7,5523 90 (Elec RS—Low output) 52 4,602 89 (Elec IS) 59 5,310 90 F25T12/RE70 (T8 ballast) (Elec RS) 48 4,048 84 724 25 watt, 2300 lumens (Elec IS) 46 4,048 88 FM28LW (HC only) (Mag HC) 60 4,210 70 49 28 watt, 2475 lumens F28T5 (Elec RS) 54 5,075 94 85 28 watt, 2900 lumens NOTES 1 Laboratory test conditions; actual wattage and lumens are ofter lower because of thermal effects. 2 The use of 34-watt “energy saving” lamps on electronic ballasts designed for T-12 lamps is not recommended due to lamp life problems and other considerations 3 Different manufacturers’ products utilize various ballast factors and input watts. This is the highest value. 4 Color rendering varies depending on CCT. Generally values range from 70 to 82.
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Table 3-9 Fluorescent Lamp Characteristics—Common 8-foot lamps
Lamp Type Input watts for 2 lamps and ballast Lumen output for a pair Efficacy CRI of lamps (lumens per watt) F96T12CW (pre-1995) (Mag Std) 172 11,180 65 62 75 watt (Slimline) (Mag EE) 158 11,180 71 6250 lumens (Elec IS) 130 11,050 85 F96T12RE70 (Mag Std)172 11,515 67 72 75 watt (Slimline) (Mag EE) 158 11,515 73 6500 lumens (Elec IS) 130 11,382 87 F96T12RE80 (Mag Std) 172 11,860 69 82 75 watt (Slimline) (Mag EE) 158 11,860 75 6800 lumens (Elec IS) 130 11,723 89 F96T12/ES/CW (Mag Std) 135 9,135 68 62 60 watt (Slimline) (Mag EE) 123 9,135 74 5500 lumens (Elec IS) 105 8,925 85 F96T12/ES/RE70 (Mag Std) 135 9,409 70 72 60 watt (Slimline) (Mag EE) 123 9,409 76 5700 lumens (Elec IS) 105 9,192 87 F96T12/ES/RE80 (Mag Std) 135 9,691 72 82 60 watt (Slimline) (Mag EE) 123 9,691 78 6000 lumens (Elec IS)105 9,467 89 F96T12/HO/CW (pre-1995) (Mag Std) 252 15,632 62 62 110 watt (Mag EE) 237 15,632 66 8800 lumens (Elec RS) 190 14,365 76 F96T12/HO/RE70 (Mag Std) 252 16,100 64 72 110 watt (Mag EE) 237 16,100 68 9200 lumens (Elec RS) 190 15,075 78 F96T12/HO/RE80 (Mag Std) 252 16,585 66 82 110 watt (Mag EE) 237 16,585 70 9350 lumens (Elec RS) 190 15,530 80 F96T12/HO/ES/CW (Mag Std) 222 13,746 62 62 95 watt (Mag EE) 208 13,746 66 8000 lumens (Elec RS) 160 12,480 78 F96T12/HO/ES/RE70 (Mag Std) 222 14,155 64 72 95 watt (Mag EE) 208 14,155 68 8350 lumens (Elec RS) 160 12,860 80 F96T12/HO/ES/RE80 (Mag Std) 222 14,580 66 82 95 watt (Mag EE) 208 14,580 70 8500 lumens (Elec RS) 160 13,245 82 F96T8/RE70 (Elec IS) 105 9,230 88 75 59 watt 5800 lumens F96T8/RE80 (Elec IS) 105 9,510 91 85 59 watt 5950 lumens F96T8/HO/RE70 (Elec RS) 160 13,550 85 75 86 watt 8000 lumens F96T8/HO/RE80 (Elec RS) 160 13,960 87 85 86 watt 8200 lumens
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Other Fluorescent Technologies
Significant advances in fluorescent lighting technology have resulted in several major innovations. The more important include: x Low-mercury fluorescent lamps Until a lamp using totally non-toxic technology is developed, fluorescent lamps will continue to serve as the mainstay for most commercial lighting. Recent advances in mercury dosing technology assure that lamps receive only the very smallest amount of it — and in turn, pass the EPA’s Toxic Characteristic Leaching Procedure (TCLP) test for hazardous waste. This manufacturing process is being applied to 34-watt T-12 lamps as of 1996, and lamps bearing the distinctive green end band (or otherwise marked) can be discarded as non-hazardous waste when they fail. x Smaller-diameter T-5 straight lamps Probably the last reduction in lamp diameter for full-size lamps, the T-5 lamp increases the efficacy over T-8 lamps, generating more light per watt than any other general lighting fluorescent lamp. Technical limitations to the manufacture and operation of small diameter lamps have been overcome, although concerns over source brightness will limit applications and continue to assure the viability of the T-8 lamp as the mainstream lamp of the future. Straight T-5 lamps are not 4 ft long. Further restricting retrofit applications. x Even smaller diameter T-2 lamps Although the lamps are too delicate for long tubes, small diameter lamps up to 20” long have been introduced and are expected to play a major role in making energy-efficient specialty lighting applications.
Among these, the low-mercury lamps are expected to play a major role in retrofitting, while the smaller- diameter lamps will be useful in certain applications.
High-Intensity Discharge Lamps
Lighting systems using high-intensity discharge (HID) lamps are common in a variety of interior and exterior commercial and industrial applications. Improvements in energy efficiency for HID systems are often harder to identify and implement, in large part due to the inherently high efficacy of modern HID systems. However, recent technology improvements present new concepts and opportunities in HID systems retrofitting with a surprising number of applications.
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Figure 3-8 High-Intensity Discharge Lamp Technology
With HID lamps, a high-temperature, high-pressure arc is created in a small “arc tube” having inert gases and metals that become vaporized once the lamp is operating. The arc tube is enclosed within a more conventional hard glass bulb. The material of the arc tube and the tube’s internal chemicals determine the type of lamp and its characteristics. The outer bulb may be clear, diffuse-coated to distribute and soften the intense arc, or phosphor-coated to both diffuse the arc and modify the lamp color. Generally, clear lamps are used in luminaires which have high performance or precision optics, and coated lamps are used in less demanding luminaires. This is especially important in retrofitting.
Current through the lamp is regulated by a ballast, of which there are several different types. The initial arc of the lamp is started by an ignition circuit that may be internal to the lamp, integral to the ballast, or external to both. All HID lamps share the characteristics of: x Warm-up time, a period ranging from 90 seconds to 5 minutes, during which pressure and temperature build within the arc tube until nominal lamp operation is achieved. x Re-strike time, a period ranging from a few seconds to 10 minutes after the lamp is extinguished (usually accidentally or due to a power outage, even a short one), during which the arc tube must cool after being operated until the arc can be re-
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ignited. Hot or instant-restrike lamps and special ignitors exist but cost and complexity make them rare and limit applications to critical situations.
There are four major families of HID lamps, each with specific technical qualities and components that are generally NOT shared with any other HID lamp family. x Mercury vapor. Mercury vapor lamps are one of the oldest HID technologies. The arc tube is typically made of quartz glass, and the arc causes mercury vapors to emit visible and UV light. There is a wide range of lamp wattages and shapes. Mercury vapor lamps have long life, poor lumen maintenance, medium efficacy and poor to fair color. Most mercury vapor lamps are phosphor coated to improve the color. x Metal halide. Metal halide lamps were developed in the mid-1960s as an alternative to mercury vapor. The arc tube is similar and in addition to mercury vapor, other metals’ vapors (such an indium, thallium, sodium, and dysprosium) radiate other parts of the spectrum. The result is a family of lamps with good to excellent color, high efficacy, and medium-to-long life. Metal halide lamps have a number of application considerations, such as position sensitivity and comparatively fair lumen maintenance, that make them a bit harder to apply with consistent results. Recent developments in metal halide, including the use of a ceramic arc tube and new ballasts (see below) are expected to make even bigger improvements in metal halide applicability. x High-pressure sodium (HPS). HPS lamps typically utilize a ceramic arc tube and rely principally upon the spectrum emitted by vapors of sodium to create a yellowish-white light. HPS lamps have extremely long life and high lumen maintenance. Variations on high-pressure sodium include so-called “white” sodium lamps which have significantly improved color while sacrificing some of the more desirable qualities such as length of lamp life. The importance of HPS in street lighting is tremendous, and special products like a double arc-tube lamp (instant restrike, extremely long life) are made especially for this application.
Low-pressure sodium (LPS). With LPS lamps, the arc operates at lower temperature, and is therefore noticeably longer and less compact than HPS. But because of its warm- up characteristics, LPS is generally considered an HID lamp. The spectrum emitted is monochromatic yellow, making illuminated colors indistinguishable. Extremely high efficacy, long life, and excellent lumen maintenance make these lamps technically appealing, although the seriously deficient color limits applications considerably.
Table 3-10 Properties of HID Lamps
Quality Mercury Vapor Metal Halide High-Pressure Low-Pressure Sodium Sodium Bulb shapes A, BT, E, ED, R, PAR, BT, E, ED, R, PAR, T, E, ED, R, PAR, T, T only others others others Sockets Medium ceramic; mogul Medium ceramic pulse Medium ceramic pulse special twin-post ceramic rated; mogul ceramic; rated; mogul ceramic 3-24 Retrofit Technologies
recessed single contact pulse rated; recessed ceramic; Others: Special single contact ceramic; socket for lamps not others requiring protective lens cover; Special socket for position-oriented lamps Wattages 50, 70, 100, 175, 250, 32, 35, 50, 70, 100, 150, 35, 50, 70, 100, 150, 18, 35, 70, 100, 135, 400, 1000 175, 250, 325, 360, 400, 200, 250, 400, 1000 180 650, 700, 950, 1000, 1500, and others 2000 Ballast types Linear reactor NPF; Linear reactor HPF; Linear reactor NPF; Linear reactor HPF; linear reactor HPF; constant wattage linear reactor HPF; constant wattage constant wattage autotransformer; auto- constant wattage autotransformer autotransformer (CWA); regulator; lead-peaked auto- autotransformer; auto-regulator reg; electronic; DC electronic; DC electronic; hybrid electronic Ignitors Internal to lamp Internal to lamp (175-watt Internal to ballast or Internal to ballast min.); internal to ballast or lamp or external to external to both (all both wattages) Color Clear: 4700K, 10 CRI Standard clear: 4100K, 65 Standard clear and 1800K no color rendition DX: 4100K, 50 CRI CRI Standard coated: coated: 2100K, 22 WDX: 3300K, 50 CRI 3700K, 70 CRI Warm clear: CRI Deluxe clear and /N: 3300K, 65 CRI 3200K, 65 CRI Warm coated: 2200K, 65 CRI coated: 3000K, 70 CRI HQI “White”: 2500-2800K, clear: 3000K, 85 CRI or 70-85 CRI 4100K, 85 CRI Ceramic arc tube clear and coated: 3000K, 85 CRI. Other types exist for special applications; saturated colors available Luminous Efficacy 25 to 60 LPW 50 to 110 LPW 35 to 140 LPW 80 to 140 LPW (initial) Retrofit Opportunities Replace with high- (1) Replace low-wattage None recommended None recommended wattage compact units with high-wattage fluorescent, metal halide, compact fluorescent; (2) or high-pressure sodium Replace standard lamps with reduced watt versions (3) Change ballast to more energy-efficient version; (4) Install self-protected lamp, eliminate lens to improve LDD factor
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Ballasts for HID Lamps
Conventional “magnetic” HID ballasts can be complex devices with several functions. When retrofitting a luminaire, the electrician is often faced with several discrete components in a “core and coil” arrangement, which in fact is the core-and-coil assembly and one or more other components. Encased ballasts generally include: x the actual ballast, generally a winding (coil) on an iron transformer core that might also be shared with other windings x a transformer, also consisting of winding(s) on the core which adjust the building input voltage to match the lamp open-circuit voltage x a capacitor for power-factor correction x an ignitor and/or other specialized electronics
There are an increasing number of electronic ballasts for HID lamps. Electronic ballasts generally cannot realize the same types of savings for HID lamps as they do for fluorescent. This is in part because high-frequency operation offers no advantages (other than size and weight) for HID lighting, and in part because many HID lamps cannot be operated at high-frequency lest they experience mechanical resonance and explode. However, a major advantage of the electronic ballast is reduced size and weight as compared to magnetic ballasts. Current products include 60 Hz, high- frequency and DC lamp operation.
Electronic ballasts are standard for a few HID lamp types and offer a slight increase in efficiency. But the real promise of HID electronic ballasts, especially for metal halide, is improved lamp management over life, making lamp color more consistent, decreasing lumen depreciation, and perhaps adding other features such as accelerated warm-up or decreased re-strike time.
Retrofitting Opportunities
This section describes some of the common retrofit opportunities for buildings with HID lamps.
Mercury Vapor Lamps.
1. Some mercury vapor lamps may be replaced by a similar sized metal halide (“I- line”) lamp. The most common is a 325-watt metal halide specifically designed for operating on a 400-watt mercury vapor ballast, saving 75 watts per luminaire and generating 30% more light. 2. High-wattage mercury vapor luminaires are increasingly rare. Those without precise optical systems, such as decorative outdoor lighting poles, most landscape lighting, and many types of industrial lighting, can be converted to a metal halide lamp of about 60% of the watts, generally using diffuse-coated lamps, with minor 3-26 Retrofit Technologies
concern for lamp optical centering (see below). Unless an advanced metal halide system is being considered, it is unlikely that the socket or wiring will require changing, as there are many metal halide and high-pressure sodium lamps that are simple screw-in replacements to mercury vapor lamps. 3. Even if the luminaire has a precise optical system, in many cases a conversion to metal halide will work well. Generally replace a mercury vapor lamp with a metal halide using 60% of the mercury lamp’s rated wattage. Be certain to take into account the optical center of the bulb or arc, as the lower-wattage metal halide lamp will be smaller; a socket extender or new socket assembly may be needed. Be certain to note whether the metal halide lamp requires a “pulse rated” socket, meaning the ignitor is not within the lamp (typical for 150 watts and less and certain high- performance lamps and the latest “energy-efficient” lamp-ballast systems). Generally a pulse-rated socket signifies that the ignitor must be physically near the lamp and that the wiring between ignitor and socket be rated for high voltage pulses as well. 4. Low-wattage mercury vapor lamps can be retrofitted with compact fluorescent lamps so long as the optical system is insignificant. For instance, a 70–100-watt mercury vapor lamp may be replaced with an electronically-ballasted 40–42-watt “triple” or coiled compact fluorescent and produce the same maintained light output, taking advantage of the superior lumen maintenance of the modern amalgam compact fluorescent lamp and the low-temperature starting of the electronic ballast. Or, a low-wattage metal halide (50 watts for this example) might be used—but note that this may also require pulse rated socket and socket wiring. The primary risk with fluorescent-for-HID conversions of any kind is temperature extremes—very warm or very cold environmental conditions often favor HID, electronic ballasts for fluorescent notwithstanding. 5. In all cases, before retrofitting a mercury vapor luminaire, investigate complete luminaire replacement. The majority of the mercury luminaires in service are 15–20 years old or more. In addition, conversion may cost less if the labor of changing luminaires is less than the labor of rewiring—it often is.
Table 3-11 Mercury Vapor Input Watts
Lamp Watts Ballast Type Input Watts Notes
75 Reactor 85 120 volt at PF=.45
CWA 99 HPF
100 CWA 110 120 volt at PF=.45
120–125 HPF
175 CWA 195–210 HPF
250 CWA 290–300 HPF
400 CWA 450 HPF
1000 CWA 1050–1060 HPF
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Metal Halide Lamps. Many metal halide luminaires cannot be retrofitted within the economic parameters of an energy efficiency project. The basic source is too efficacious and the near point-source of the arc tube lends itself to efficient luminaires. However, there are a few ways in which savings might be achieved by retrofitting.
1. If frequent switching is being avoided due to the warm-up and re-strike problems of the metal halide lamp, consider retrofitting with a new fluorescent lighting system. 2. When a space is overlighted, install a dimming ballast to reduce idling power. Applications might include warehouses, areas with some daylighting, and airport ramps when aircraft are no longer being serviced.
3. Some metal halide lamps are burning-position sensitive and will not operate properly unless the arc tube is in a particular alignment relative to gravity. Lamps with the suffix “U”, e.g. M250/U, can be operated in any position (although slightly better operation may occur in some positions). Position-specific lamps include suffixes like: x /BU base up (usually within 15 degrees) x /BD base down (usually within 15 degrees) x /BUH base up to horizontal x /BDH base down to horizontal x /HOR horizontal (usually within 45 degrees)
There are ways to prevent many of these lamps from being used incorrectly. For example, the /HOR “high-output” single-ended lamps have a slightly curved arc tube that must be aligned with the curve oriented vertically or the lamp will operate quite poorly. Note that the high-output lamps generate about 10% more lumens than universal lamps of the same wattage. It is important to retrofit position- sensitive lamps properly. Also note that there may be some retrofit advantage through the higher light output, the difference in light between universal and high output lamps is not great. 4. There are a few “low-wattage” metal halide lamps allowing direct replacement. These include the 360-watt replacement for the 400-watt lamp and the 950-watt replacement for the 1000-watt lamp. These are socket-for-socket changeout products. 5. Some systems lend themselves toward new ballasts and lamps. In particular, the 400-watt standard metal halide can be changed to a 360-watt lamp and reactor ballast if the input power is 277 volts, resulting in negligible light level change and savings of about 70 watts per luminaire. Other systems may be harder to implement. 6. There is a hybrid ballast system for metal halide lamps that attempts to better regulate arc voltage over life, thereby increasing lumen maintenance. Under favorable conditions a 250-watt hybrid system might be used to replace a 400-watt system. This could result in equal maintained illumination even if the initial
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illumination of the 250-watt system is much lower. Remember, lumen maintenance of metal halide lamps is notoriously poor; but the actual cause is due to lamp voltage rise caused by slow changes in lamp chemistry and therefore, the lamp’s electric resistance. A hybrid ballast compensates for the changes, whereas a magnetic ballast cannot. 7. Most metal halide luminaires incorporate a lens to protect room occupants in case of a lamp explosion. In some luminaire types, such as downlights and industrial fixtures, the lens may collect dirt which would not otherwise affect an open bottom luminaire. Consider changing the socket to the type suitable for metal halide lamps that have an internal arc-tube shroud. The slight reduction in initial lamp lumens of the shrouded-tube lamp, about 10%, is offset by eliminating the light absorption of the original lens. The result might be much higher maintained light levels as the luminaire’s dirt depreciation (LDD) can improve dramatically. 8. Very low wattage metal halide, especially lamps under 100 watts, might be replaced with a 40–42-watt compact fluorescent. 9. There are several special metal halide families of which some are quite common, like the double-ended 70- and 150-watt HQI. Make special note of these lamps, as the opportunities are very limited. For instance, there are electronic ballasts for the 70-watt HQI lamp that offer both improved lumen maintenance and higher efficiency than magnetic ballasts. But due to many of the technical properties of these lamps, they will otherwise be hard to change to save energy. 10. There are also many uncommon metal halide lamps, like the CSI, CID, HMI, etc. Most of these are special purpose lamps intended for film, theater, or other uncommon applications. Their unusual nature suggests looking into other luminaires and lamps if the situation seems appropriate for a change.
The following tables show typical metal halide lamps intended for general use as of summer 1996. Among the areas of evolution for new products will be low-wattage high CRI lamps; high-wattage 3000K, high CRI lamps; and low-wattage high CRI projector lamps.
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Table 3-12 Metal Halide Lamp Data—Non-Reflector Lamps
Watts ANSI Input Lamp Base Envelope CCT CRI Coated or Initial Nominal Code Watts Type (K) Clear Lumens Lamp Life (nominal) (Hrs.) 32 M100 38 E V Medium E17 3000 70 Coated 2500 10,000 39 M130 47 E U G12 T6 3000 81 Clear 3300 9000 50 M110 72 HX U Medium E/ED17 3700 70 Coated 3400 5000 U 4000 65 Clear 3400 5000 U/SB 4000 65 Clear 3200 5000 BU105 G12 T8 4000 65 Clear 3400 10,000 BU105 3200 65 Clear 3400 10,000 U/Open Medium E/ED17 3200 65 Clear 3300 5000 U/Open 3200 65 Coated 2800 5000 70 M98 94 HX U Medium E/ED17 3700 70 Coated 5600 10,000 U 4000 65 Clear 5600 10,000 U/SB 3200 65 Clear 6000 10,000 10,000 BUBD15 3200 65 Coated 6000 Mogul E/ED28 65 Clear BUBD15 4000 5200 4000 65 Clear 5600 U BU105 G12 T8 4000 65 Clear 5600 10,000 U 3000 83 Clear 6200 U 3000 83 Coated 6000 BU105 3200 65 Clear 5600 10,000 U/Open Medium E/ED17 3200 65 Clear 5200 10,000 U/Open 3200 65 Coated 4800 10,000 U/Open 3000 83 Clear 5900 10,000 U/Open 3000 83 Coated 5700 10,000 Vert Open 3200 65 Clear 6000 10,000 Vert Open 3200 65 Coated 5600 10,000 Vert Open Mogul E/ED17 3200 65 Clear 6000 10,000
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Table 3-12 Metal Halide Lamp Data—Non-Reflector Lamps (continued)
Watts ANSI Input Lamp Base Envelope CCT CRI Coated or Clear Initial Nominal Code Watts Type (K) Lumens Lamp Life (nominal) (Hrs.) 70 M85 94 HX HOR45 RSC T6.5 4200 65 Clear 5500 7500 80 E HOR45 3500 65 Clear 5500 7500 HOR45 3000 65 Clear 5000 7500 HOR45 4200 85 Clear 5500 10,000 HOR45 3000 81 Clear 5000 10,000 HOR45 T6 3000 82 Clear 6200 6000 BU105 G12 T8 4000 65 Clear 3400 10,000 BU105 3200 65 Clear 3400 10,000 U 3000 83 Clear 6200 6000 75 M101 94 HX BU15 Medium ED17 3200 65 Clear 5600 5000 BU15 3200 70 Coated 5200 5000 100 M90 125 HX U Medium E/ED17 3700 70 Coated 7800 10,000 U 4000 65 Clear 7800 10,000 U/SB 4000 65 Clear 7600 10,000 5200 65 Clear 7000 7500 U Mogul E/ED28 4000 65 Clear 7800 10,000 U BUBD15 Medium ED17 3200 65 Clear 9000 10,000 BUBD15 3200 70 Coated 8500 10,000 BU105 G12 T8 4000 65 Clear 9000 10,000 BU105 3200 65 Clear 9000 10,000 U 3000 85 Clear 9300 10,000 U 3000 85 Coated 9000 10,000 U/Open Medium E/ED17 3200 65 Clear 8500 10,000 U/Open 3200 65 Coated 8000 10,000 U/Open 3000 85 Clear 8800 10,000 U/Open 3000 85 Coated 8500 10,000 Vert/Open 3200 65 Clear 9000 10,000 Vert/Open 3200 65 Coated 8500 10,000 Vert/Open Mogul E/ED17 3200 65 Clear 9000 10,000 100 M91 130 HX HOR45 RSC T7.5 4200 65 Clear 6800 7500 150 M107 195 CWA U Medium E/ED17 3700 70 Coated 13500 10,000 U 4000 65 Clear 13500 10,000 U Mogul E/ED28 4000 65 Clear 13500 10,000 U 3700 70 Coated 13500 10,000 BUBD15 Medium ED17 3200 70 Coated 12500 10,000 150 M102 180 HX U Medium ED17 4000 65 Clear 15000 15,000 U 3700 70 Coated 14250 15,000 Vert open E17N 4000 65 Clear 14250 15,000 Vert open 3700 70 Coated 13500 15,000 Vert open 3200 70 Clear 14250 15,000 Vert open 3200 75 Coated 13500 15,000 U Mogul ED28 4000 65 Clear 15000 15,000 U 3700 70 Coated 14250 15,000 Vert open OP Mog ED28 3200 65 Clear 14250 15,000 Vert open 3200 70 Coated 13500 15,000 Vert open 2700 75 Coated 13500 15,000
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Table 3-12 Metal Halide Lamp Data—Non-Reflector Lamps (continued)
Watts ANSI Input Lamp Base Envelope CCT CRI Coated or Clear Initial Nominal Code Watts Type (K) Lumens Lamp Life (nominal) (Hrs.) 150 M81 180 HX HOR45 RSC T7.5 4200 65 Clear 12,000 10,000 HOR45 3500 65 Clear 12,000 10,000 HOR45 3000 65 Clear 11,500 10,000 HOR45 4200 85 Clear 11,250 10,000 HOR45 3000 81 Clear 11,000 10,000 HOR45 T6 3000 85 Clear 13,500 6000 U G12 T6 3000 85 Clear 13,500 6000 175 M57 205 U Medium E/ED17 3700 70 Coated 15,000 10,000 CWA U 4000 65 Clear 15,000 10,000 U Mogul E/ED28 3700 70 Coated 14,000 10,000 4000 65 Clear 14,000 10,000 U 4000 65 Clear 13,600 10,000 U/SB 5200 65 Clear 12,000 7500 U BU15 Medium ED17 3200 70 Coated 14,000 10,000 BUBD15 Mogul ED23½ 3200 65 Clear 16,600 10,000 BUBD15 3200 65 Coated 15,750 10,000 BU15 E/ED28 3200 65 Clear 14,000 10,000 BU15 4000 65 Clear 14,000 10,000 BU15 3200 70 Coated 13,000 10,000 BU15 3700 70 Coated 14,000 10,000 HOR45 PO Mogul E/ED28 3200 70 Coated 14,000 10,000 HOR45 3700 70 Coated 15,000 10,000 HOR45 4000 65 Clear 15,000 10,000 HOR45 4200 70 Coated 15,000 10,000 HOR45 4700 65 Clear 15,000 10,000 200 U Mogul ED28 4000 65 Clear 21,000 15,000 U PO Mogul ED28 3700 70 Coated 20,000 15,000 Open Vert OFMogul ED28 4000 65 Clear 19,000 15,000 Open Vert OF Mogul ED28 4000 65 Clear 20,000 15,000 Open Vert OF Mogul ED28 3700 70 Coated 20,000 15,000 Open Vert OF Mogul ED28 3200 70 Coated 19,000 15,000 225 M58 265 BU15 Mogul ED28 4000 65 Clear 19,000 10,000 CWA (Energy BU15 3700 70 Coated 19,000 10,000 Saving Lamp) OpenBU15 4000 65 Clear 19,000 10,000 OpenBU15 3700 70 Coated 19,000 10,000
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Table 3-12 Metal Halide Lamp Data—Non-Reflector Lamps (continued)
Watts ANSI Input Lamp Base Envelope CCT CRI Coated or Clear Initial Nominal Code Watts Type (K) Lumens Lamp Life (nominal) (Hrs.) 250 M58 290 U Mogul E/ED28 3700 70 Coated 20,500 10,000 CWA U 4000 65 Clear 20,500 U/SB 4000 65 Clear 20,000 U 5200 65 Clear 19,000 7500 U ED18 4000 65 Clear 20,500 10,000 BU15 Mogul E/ED28 3200 70 Coated 20,500 10,000 BU15 3700 70 Coated 23,000 10,000 BU15 4000 65 Clear 23,000 10,000 HOR45 PO Mogul E/ED28 3200 70 Clear 20,500 10,000 HOR45 3700 70 Coated 23,000 10,000 HOR45 4000 65 Clear 23,000 10,000 M80 HOR15 RSC T9.5 4200 65 Clear 20,000 10,000 HOR45 4200 85 Clear 20,000 10,000 HOR45 RSC/Fc2 T9.5 5400 93 Clear 19,000 10,000 HOR45 4200 85 Clear 20,000 10,000 HOR15 4200 65 Clear 20,000 10,000 HOR45 3200 85 Clear 20,000 10,000 325 H33 375 U Mogul ED37 4000 65 Clear 28,000 20,000 CWA Mercury U 3700 70 Coated 28,000 20,000 retrofit 350 M131 408 U Mogul ED37 4000 65 Clear 36,000 20,000 CWA
375 LR U 3700 70 Coated 34,500 20,000 HOR45 PO Mogul 4000 65 Clear 35,000 20,000 HOR45 3700 70 Coated 33,500 20,000 U Mogul ED28 4000 65 Clear 36,000 20,000 U 3700 70 Coated 34,500 20,000 HOR45 PO Mogul 4000 65 Clear 35,000 20,000 HOR45 3700 70 Coated 33,500 20,000 Open Vert OFMogul BT37 4000 65 Clear 36,000 20,000 Open Vert 3700 70 Coated 34,500 20,000 Open Vert ED28 4000 65 Clear 36,000 20,000 Open Vert 4000 65 Clear 34,500 20,000 360 M59 418 BU15 Mogul ED37 4000 65 Clear 35,000 20,000 CWA (Energy BU15 3700 70 Coated 35,000 20,000 Saving Lamp) BD15 4000 65 Clear 35,000 20,000 HOR45 PO Mogul 4000 65 Clear 35,000 20,000 HOR45 3700 70 Coated 35,000 20,000 BU15 Mogul ED28 4000 65 Clear 35,000 20,000 Open-BU15 BT37 4000 65 Clear 35,000 20,000 Open-BU15 3700 70 Coated 35,000 20,000
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Table 3-12 Metal Halide Lamp Data—Non-Reflector Lamps (continued)
Watts ANSI Input Lamp Base Envelope CCT CRI Coated or Clear Initial Nominal Code Watts Type (K) Lumens Lamp Life (nominal) (Hrs.) 400 M59 458 U Mogul E/ED37 3700 70 Coated 36,000 20,000 CWA U 4000 65 Clear 36,000 20,000 425 LR U/SB 4000 65 Clear 35,000 20,000 440 U 5200 65 Clear 32,500 15,000 CWI (2 U ED28 3700 70 Coated 36,000 20,000 Lamp, U 4000 65 Clear 36,000 20,000 each lamp) BU15 Mogul E/ED37 3200 70 Coated 36,000 20,000 BU15 3700 70 Coated 40,000 20,000 BU15 4000 65 Clear 40,000 20,000 BD15 4000 65 Clear 40,000 20,000 HOR45 PO Mogul E/ED37 3200 70 Coated 36,000 20,000 HOR45 3700 70 Coated 40,000 20,000 HOR45 4000 65 Clear 40,000 20,000 HOR20 4000 65 Clear 40,000 20,000 HOR20 4000 65 Clear 40,000 20,000 Open/BU15Mogul E/BT37 3200 70 Coated 35,000 20,000 Open/BU15 3500 70 Coated 35,500 20,000 Open/BU15 3700 65 Clear 35,500 20,000 400 M108 460 HOR45 RSC T10 4200 65 Clear 34,000 15,000 CWA HOR45 Fc2D T10 4200 65 Clear 40,000 15,000 HOR45 Fc2 T10 5400 93 Clear 33,000 10,000 950 M47 1040 U Mogul BT56 4000 65 Clear 105,000 12,000 CWA 1000 M47 1090 U Mogul BT56 3700 70 Coated 110,000 12,000 CWA U 4000 65 Clear 110,000 12,000 U/SB 4000 65 Clear 107,000 12,000 U 5200 65 Clear 80,000 9000 BU15 3400 70 Coated 117,000 12,000 BU15 3900 65 Clear 117,000 12,000 BU15 3900 65 Clear 117,000 12,000 HOR60 3400 65 Clear 117,000 12,000 OpenBU15 3400 65 Coated 110,000 12,000 OpenBU15 3400 65 Clear 110,000 12,000 1000 M47 1090 HOR15 RSC T9.5 3800 65 Clear 100,000 3000 Special CWA Igniter 1500 M48 1595 U Mogul BT56 3400 65 Clear 155,000 3000 CWA U 4000 65 Clear 155,000 3000 HBU105 Mogul BT56 3400 65 Clear 155,000 3000 HBD105 3400 65 Clear 155,000 3000 HOR60 PO Mogul 3400 65 Clear 162,000 3000 1500 M48 1595 HOR15 RSC T7.5 3800 65 Clear 150,000 2000 Special CWA Igniter HOR15 T9.5 3800 65 Clear 150,000 2000 1650 M48 1750 HOR60 PO Mogul BT56 3400 65 Clear 177,000 3000 CWA 1800 Special 1975 HOR15 Special T-D 5600 92 Clear 150,000 4500
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Table 3-12 Metal Halide Lamp Data—Non-Reflector Lamps (continued)
Watts ANSI Input Lamp Base Envelope CCT CRI Coated or Clear Initial Nominal Code Watts Type (K) Lumens Lamp Life (nominal) (Hrs.) 400 M59 458 U Mogul E/ED37 3700 70 Coated 36,000 20,000 CWA U 4000 65 Clear 36,000 20,000 425 LR U/SB 4000 65 Clear 35,000 20,000 440 U 5200 65 Clear 32,500 15,000 CWI (2 U ED28 3700 70 Coated 36,000 20,000 Lamp, U 4000 65 Clear 36,000 20,000 each lamp) BU15 Mogul E/ED37 3200 70 Coated 36,000 20,000 BU15 3700 70 Coated 40,000 20,000 BU15 4000 65 Clear 40,000 20,000 BD15 4000 65 Clear 40,000 20,000 HOR45 PO Mogul E/ED37 3200 70 Coated 36,000 20,000 HOR45 3700 70 Coated 40,000 20,000 HOR45 4000 65 Clear 40,000 20,000 HOR20 4000 65 Clear 40,000 20,000 HOR20 4000 65 Clear 40,000 20,000 Open/BU15Mogul E/BT37 3200 70 Coated 35,000 20,000 Open/BU15 3500 70 Coated 35,500 20,000 Open/BU15 3700 65 Clear 35,500 20,000 400 M108 460 HOR45 RSC T10 4200 65 Clear 34,000 15,000 CWA HOR45 Fc2D T10 4200 65 Clear 40,000 15,000 HOR45 Fc2 T10 5400 93 Clear 33,000 10,000 950 M47 1040 U Mogul BT56 4000 65 Clear 105,000 12,000 CWA 1000 M47 1090 U Mogul BT56 3700 70 Coated 110,000 12,000 CWA U 4000 65 Clear 110,000 12,000 U/SB 4000 65 Clear 107,000 12,000 U 5200 65 Clear 80,000 9000 BU15 3400 70 Coated 117,000 12,000 BU15 3900 65 Clear 117,000 12,000 BU15 3900 65 Clear 117,000 12,000 HOR60 3400 65 Clear 117,000 12,000 OpenBU15 3400 65 Coated 110,000 12,000 OpenBU15 3400 65 Clear 110,000 12,000 1000 M47 1090 HOR15 RSC T9.5 3800 65 Clear 100,000 3000 Special CWA Igniter 1500 M48 1595 U Mogul BT56 3400 65 Clear 155,000 3000 CWA U 4000 65 Clear 155,000 3000 HBU105 Mogul BT56 3400 65 Clear 155,000 3000 HBD105 3400 65 Clear 155,000 3000 HOR60 PO Mogul 3400 65 Clear 162,000 3000 1500 M48 1595 HOR15 RSC T7.5 3800 65 Clear 150,000 2000 Special CWA Igniter HOR15 T9.5 3800 65 Clear 150,000 2000 1650 M48 1750 HOR60 PO Mogul BT56 3400 65 Clear 177,000 3000 CWA 1800 Special 1975 HOR15 Special T-D 5600 92 Clear 150,000 4500
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Table 3-13 - Lamp Data—Metal Halide With Internal Reflectors
Watts ANSI Base Bulb Shape CCT CRI Beam Beam Center Beam Nominal Notes Code (K) Type Spread CP (nominal) Lamp Life Degrees (Hrs.)
39 M130 Medium PAR20 3000 81 Spot 10 28,000 9000 Open PAR20 Flood 30 6000 fixture PAR30L Spot 10 42,000 PAR30L Flood 30 6500 70 M98 Medium R40 4000 65 Spot 15 60,000 10,000 Flood 70 1500 10,000 Med. Skt. PAR38 4300 65 Spot 15 40,000 5000 Open fixture Flood 35 12,000 5000 Open fixture 3200 65 Spot 20 18,000 7500 Open fixture Flood 35 10,000 7500 Open fixture Flood 65 3000 7500 Open fixture 3000 81 Spot 15 28,000 7500 Open fixture Flood 30 16,000 7500 Open fixture Wide flood 65 4000 7500 Open fixture Medium PAR30L 3000 83 Spot 10 48,000 6000 Open fixture Flood 40 7000 6000 Open fixture Mog. Prong PAR56 4300 65 Spot 20 105,000 5000
100 M90 Medium R40 4000 65 Spot 15 80,000 10,000 Flood 70 3300 10,000 Med. Skt. PAR38 3200 65 Spot 20 26,000 7500 Open fixture Flood 35 12,000 7500 Open fixture Flood 65 4500 7500 Open fixture 3000 83 Spot 15 40,000 7500 Open fixture Flood 30 21,000 7500 Open fixture Wide flood 65 6000 7500 Open fixture Mog. Prong PAR56 4300 65 Spot 20 106,000 5000 175 M57 Medium R40 4000 65 Spot 15 95,000 10,000 Flood 70 6500 10,000 Mog. Prong PAR56 4300 65 Spot 20 108,000 5000 250 M58 Mog. Prong PAR64 4300 65 Spot 15 210,000 5000
400 M59 Mog. Prong PAR64 4300 65 Spot 30 120,000 5000
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1000 * Mog. Prong PAR64 4000 88 Spot 8 1,500,000 5000 *CSI Type 5600 92 Spot 8 1,200,000 5000 *CID Type Table 3-14 - Basic Application Notes for Metal Halide and HPS Lamp Tables
Item Considerations Watts Nominal lamp watts at 100 hours. Actual lamp watts will vary over life and depending on input voltage and other factors. ANSI Code American National Standards Institute (ANSI) code defining lamp physical and electrical characteristics to ensure interchangability and standardization among manufacturers. Metal halide codes begin in M, HPS codes in S, mercury vapor lamp codes in H. Input Watts Nom. Ballast input watts. Note that the difference between input watts and lamp watts is wasted energy dissipated as ballast heat. Ballast type varies input watts. Ballast types as follows: E Electronic or hybrid electronic HX High reactance autotransformer CWA Constant wattage autotransformer CWI Constant wattage isolated transformer LR Linear reactor Lamp Type Describes lamp operating position and fixture requirements as follows: U = universal operating, enclosed U/SB = universal operating, enclosed, silver bowl U/Open = universal operating, open fixture Vert open = vertical burning +/- 15q base up or down, open fixture BUBD15 = base up or base down +/- 15°, enclosed BU15 = base up +/- 15°, enclosed fixture BD15 = base down +/- 15°, enclosed fixture HBU105 = horizontal to base up +/- 105°, enclosed HOR15 = horizontal +/- 15°, enclosed HOR45 = horizontal +/- 45°, enclosed HOR20 = horizontal +/- 20°, enclosed HOR60 = horizontal +/- 60°, enclosed Note that most double-ended and G12 based metal halide lamps require enclosures which prevents UV radiation from the luminaire. Base Describes lamp base or socket as follows: Medium = Pulse-rated medium base Mogul = Mogul base, usually pulse-rated PO Mogul = position-oriented mogul base G12 = bi-pin pulse-rated G12 base OF Mogul = open-flanged mogul base, usually pulse-rated, designed to accept only open fixture-rated lamps RSC = recessed single contact (double-ended lamp), pulse-rated FC2. FC2D = single contact, tab specific (double-ended lamp), pulse-rated Mogul Prong = mogul end prong Special “hot re-strike” versions of some lamps require special sockets and separate anode wires to allow high voltage pulse (20–30kV) to reignite a hot lamp. Envelope Lamp bulb type and shape. Letters designate shape as follows: E = elliptical ED = modified elliptical B = bulb (generic and arbitrary) T = tubular BT = bulb/tubular R = reflector PAR = parabolic aluminized reflector Numbers indicate lamp diameter in 1/8” increments. Lamp sizes (overall length, etc.) are standardized by NEMA and ANSI. CCT Correlated color temperature in Kelvins. Note that metal halide lamps may not visually match fluorescent or incandescent lamps of the same CCT. CRI Color rendering index. Coated or Clear Clear metal halide lamps generally have lower CRI than coated metal halide lamps but permit more effective focusing of light due to small source area of arc tube. Coated lamps diffuse light over the surface of the lamp
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and are better suited for conditions where the lamp might be viewed (as in downlighting or floodlighting) or where a more uniform source is needed. Lamp lumens Rated lamp lumens at 100 hours in preferred operating position. Note that lamp lumen depreciation can be a major factor in metal halide lamps, and that mean lumens can be as low as 75% of initial. Nominal Life Rated lamp life in preferred operating position. Note that operating position and other factors can affect lamp life. High-Pressure Sodium Luminaires. Like metal halide luminaires, high-pressure sodium luminaires are difficult to make more energy-efficient. HPS lamps are extremely long-lived, energy-efficient, and cost-effective. Moreover, there are few, if any, low-wattage lamps that can be used for direct replacements at reasonable cost. The opportunities are generally limited to the following: 1. As with metal halide (above), replace HPS systems with fluorescent lighting systems in spaces where switching opportunities are being avoided due to the warm-up and re-strike time of HPS.
2. Also, as with metal halide, add hi-lo or dimming ballast systems where idling periods of reduced lighting are appropriate. 3. Similarly, very low wattage high-pressure sodium might be replaced with high- wattage compact fluorescent lamps in similar luminaires. But unlike metal halide lamps, HPS lamps do not suffer the severe lumen depreciation; so for the most part, an electronically-ballasted compact fluorescent of 32–40 watts might be a suitable replacement for an HPS lamp of 50–70 watts at the most.
“Deluxe” sodium lamps are very much like regular HPS lamps in many considerations except that dimming features are generally not applicable. “White” sodium lamps are fairly low efficacy, medium-life lamps, and are not at all like regular HPS sources. Low-wattage white sodium luminaires can be evaluated for retrofit depending on the application. For instance, if being used as a wallwasher or down light, it may be possible to retrofit the luminaire with a compact fluorescent lamp of lower wattage. Higher-wattage white sodium lamps might be retrofitted with a lower-wattage metal halide. Because of the color rendition and other issues related to these applications, be especially aware of the design intent and how the outcome might maintain or improve the situation.
The popularity of HPS lamps for exterior lighting is now being challenged. Research indicates significant potential for improved apparent brightness and visibility with “white” light sources like metal halide and fluorescent in many lighting situations indoors and out. Some retrofit situations are intended solely to improve color rendering and gain the increased “visibility.” When doing so, consider replacing standard HPS systems with advanced metal halide or fluorescent systems so that some energy savings might be realized anyway.
For the most part, innovations and developments in HPS lamps/ballast technology appear to be reaching maturity. However, there is one significant development. New lamps are available that do not cycle on-and-off at the end of their life like typical HPS 3-38 Retrofit Technologies lamps, removing one of the maintenance hassles. The following tables represent the marketplace of general illumination lamps as of summer 1996.
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Table 3-15 Lamp Data—High-Pressure Sodium, Non-Reflector
Watts ANSI Input Base Bulb Shape Coated or CCT CRI Initial Nominal Code Watts Clear Lumens Lamp Life (nominal) (Hrs.) 35 S76 55 HX Medium E/B17 Clear 2000 18 2250 16,000 Coated 2000 18 2150 16,000 T10 Clear 2000 18 2100 16,000 S99 45 Elec PG12 T10 Clear 2700 85 1250 10,000 50 S68 65 HX Medium E/B17 Coated 2050 20 3800 16,000 Clear 2050 20 4000 16,000 T10 Clear 2050 20 3700 16,000 ED17 Clear 2700 85 2350 10,000 Mogul ED23½ Clear 2050 20 4000 16,000 Coated 2050 20 3800 16,000 S104 68 Elec PG12 T10 Clear 2700 85 2500 10,000 70 S62 90 HX Medium E/B17 Coated 2050 20 5985 16,000 Clear 2050 20 6300 16,000 T10 Clear 2050 20 6300 16,000 Mogul E/ED23½ Coated 2050 20 5985 16,000 Clear 2050 20 6300 16,000 Clear 2050 20 6300 16,000 Medium B17 Clear 2200 65 3800 15,000 Coated 2200 65 3600 15,000 ED17 Clear 2200 65 4400 15,000 Coated 2200 65 4180 15,000 Mogul ED23½ Clear 2200 65 4400 15,000 Coated 2200 65 4180 15,000 S88 94 HX RSC T6 Clear 2200 22 7000 10,000 95 Proprietary 122 Elec Med T10 Clear 2800 79 5200 10,000 E27 Clear 2800 79 5000 10,000 PG12 Clear 2800 79 5200 10,000 100 S54 125 HX Medium B17 Coated 2050 20 8500 40,000 Clear 2050 20 9500 24,000 Mogul E/ED23½ Clear 2050 20 9500 24,000 Coated 2050 20 8800 24,000 Clear 2050 20 9100 40,000 Medium ED17 Clear 2200 65 7300 15,000 Coated 2200 65 6940 15,000 Mogul ED23½ Clear 2200 65 7300 15,000 Coated 2200 65 6940 15,000 S105 120 Elec Medium ED-17 Clear 2700 85 4900 10,000 PG12 T10 Clear 2700 85 5200 10,000 150 S55 185 HX Medium B17 Coated 2100 22 15,000 24,000 Clear 2100 22 16,000 24,000 Mogul E/ED23½ Clear 2100 22 16,000 24,000 Coated 2100 22 15,000 24,000 Clear 2100 22 15,600 40,000 S56 185 CWA Mogul E28 Clear 2100 22 15,000 24,000 150 S55 185 HX Medium B17 Clear 2200 65 10,500 15,000 Coated 2200 65 9900 15,000 ED17 Clear 2200 65 12,000 15,000 Coated 2200 65 11,000 15,000 Mogul E23½ Clear 2200 65 10,500 15,000 Coated 2200 65 9900 15,000 ED23½ Clear 2200 65 12,000 15,000 Coated 2200 65 11,000 15,000 M81 180 HX RSC T7.5 Clear 2200 22 15,000 10,000 H39 180 CWA Mogul BT28 Clear 2200 22 13,000 24,000
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Table 3-15 Lamp Data—High-Pressure Sodium, Non-Reflector (continued)
Watts ANSI Input Base Bulb Shape Coated or CCT CRI Initial Nominal Code Watts Clear Lumens Lamp Life (nominal) (Hrs.) 200 S66 245 CWI Mogul E/ED18 Clear 2100 22 22,000 24,000 Clear 2100 22 22,000 40,000 215 H37 295 CWA Mogul BT28 Clear 2200 22 20,000 16,000 250 S50 295 CWA Mogul E28 Coated 2100 22 26,000 24,000 E/ED18 Clear 2100 22 27,500 24,000 Clear 2100 22 30,000 24,000 Clear 2100 22 27,500 40,000 T14.5 Clear 2100 22 29,000 24,000 Clear 2100 22 28,500 40,000 Mogul E/ED18 Clear 2200 65 23,000 15,000 E28 Coated 2200 65 20,000 15,000 RSC T7 Clear 2200 22 27,000 24,000 310 S67 355 CWA Mogul E/ED18 Clear 2100 22 37,000 24,000 360 H33 425 CWA Mogul BT37 Clear 2200 22 38,000 12,000 400 S51 450 CWA Mogul E/ED37 Coated 2100 22 47,500 24,000 E/ED18 Clear 2100 22 50,000 24,000 Clear 2100 22 50,000 40,000 T14.5 Clear 2100 22 50,000 24,000 Clear 2100 22 50,000 40,000 Mogul ED18 Clear 2200 65 37,500 15,000 E28 Clear 2200 65 37,400 10,000 Coated 2200 65 35,500 10,000 RSC T7 Clear 2200 22 50,000 24,000 600 S106 655 CWA Mogul T16 Clear 2100 22 90,000 24,000 750 S111 820 CWA Mogul BT37 Clear 2100 22 110,000 24,000 880 H36 965 CWA Mogul E25 Clear 2200 22 102,000 12,000 1000 S52 1080 CWA Mogul E-25 Clear 2100 22 140,000 24,000 Clear 2100 22 140,000 40,000 T21 Clear 2100 22 140,000 24,000
Low-Pressure Sodium Luminaires. Due to the visibility and color distinction issues surrounding LPS lighting, there is a strong trend away from the source to whiter light sources. Even cities that once touted their energy-efficient LPS systems are quietly changing to HPS or metal halide for major street and roadway systems.
Because of the unique optical package of LPS lamps, there are no retrofits for this technology other than the replacement of the luminaire. In fact, changing from LPS to another light source may in fact use more energy.
Interchangeable HID Lamps. Occasionally, there may be a situation where a screw-in replacement for an existing HID lamp is an effective and economical choice. Some of these situations include: x Metal halide lamps that replace HPS. The color deficiencies of HPS occasionally need to be overcome. There are a few metal halide products for this application. x Metal halide lamps that replace mercury. While mercury and metal halide lamps are very similar, there are a few specific metal halide lamps which perform optimally
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on existing mercury ballasts; the 325-watt lamp, in particular, replaces the 400-watt mercury vapor lamp: it improves color rendering, increases light levels, and saves energy at the same time. x HPS lamps that replace mercury. These lamps were designed for and extensively used in street lighting systems and for industrial luminaires.
Luminaire Retrofit Technologies
This section describes technologies that can be used to improve the efficiency of luminaires. A luminaire or light fixture is a complete system that includes a housing, lamp, ballast, and lens or diffuser. Lamps and ballast technologies are treated in the previous section. This section focuses on technologies that can be used to improve the efficiency of the luminaire. The efficiency of a luminaire is the ratio of light that leaves the luminaire compared to the light produced by the source (lamps and ballasts). The technologies presented in this section include reflectors that are installed inside troffers or as a part of fluorescent strip lights, lenses for diffusing and directing light that leaves luminaires, and special retrofit kits available to convert incandescent fixtures to compact fluorescent.
Table 3-16 Lamp Data—High-Pressure Sodium, Reflector Lamps
Watts ANSI Base Bulb Shape CCT CRI Beam Type Beam Center Beam CP Nominal Notes Code (K) Spread (nominal) Lamp Life (Hrs.)
35 S76 Medium R-38 2100 18 WFL 65 DEG 1000 16,000
70/75 S62 Med. Skt. PAR-38 2100 21 WFL 65 DEG 2200 10,000
PAR-38 2100 21 FL 50 DEG 4400 16,000
Med. Prong PAR-38 2100 21 WFL 65 DEG 2200 10,000
Medium R-38 2100 65 WFL 65 DEG 1800 10,000 "Deluxe"
Table 3-17 Low-Pressure Sodium Input Watts
Lamp Watts Lamp and Ballast Type Input Watts Note
18 L-69-HX 31
35 L-70-HX 60 480V Ballast is a reactor type
55 L-71-HX 80 480 V Ballast is a reactor type
90 L-72-HX 125 480V Ballast is a reactor type
135 L-73-HX 178 480 V Ballast is a reactor type
180 L-74-HX 220 480V Ballast is a reactor type
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Table 3-18 Lamp Data—Interchangeable HID Lamps
Watts Replaces ANSI Bulb CCT CRI Coated Burn Initial Lamp Life Notes Ballast Shape K or Pos. Lumens (Hrs.) Clear
Metal Halide Lamps
250 250W HPS S50 E/ED28 3700 70 Coated BU15 20,500 5000 Must be enclosed
4000 65 Clear BU15 20,500 5000 Must be enclosed
400 400W HPS S51 E/ED28 4000 65 Clear UNIV 36,000 5000
E/ED37 3700 70 Coated BU15 40,000 10,000
4000 65 Clear BU15 40,000 10,000
T14.5 5200 90 Clear UNIV 33,000 9000 Must be enclosed
325 400W MV H33* E/ED37 4000 65 Clear UNIV 28,000 20,000
3700 70 Coated UNIV 28,000 20,000
400 400W MV H33* E/ED37 4000 65 Clear UNIV 36,000 15,000 Works on M59 Ballast
3700 70 Coated UNIV 36,000 15,000 Works on M59 Ballast
950 1000W MV H15/H36 BT56 4000 65 Clear BU15 100,000 12,000 Works on M47 Ballast
4000 65 Clear BD15 100,000 12,000 Works on M47 Ballast
High-Pressure Sodium Lamps
150 175W MV H39 BT28 2100 22 Clear UNIV 13,000 24,000
215 250W MV H37 BT28 2100 22 Clear UNIV 20,000 16,000
360 400W MV H33 BT37 2100 22 Clear UNIV 38,000 12,000
880 1000W MV H15/36 E25 2100 22 Clear UNIV 102,000 12,000
Notes:
*Not all mercury ballasts are suitable for interchangeable lamps. Metal halide lamp values are for vertical burning position. Open fixtures for all HPS and vertical metal halide lamps; other metal halide positions require suitable enclosed luminaire. Lumen and lamp life ratings are nominal and are based on specific manufacturer data. Check with individual manufacturers for exact data. System input watts will vary depending on the ballast used. Contact the ballast manufacturer for actual input wattage.
Optical Reflectors
Many interior environments are overlighted because older buildings were designed to standards now considered obsolete or because tasks have changed. For example, many VDT-type tasks today were at one time performed with paper and pencil—a task requiring significantly higher levels of illuminance. Obviously, if a space has twice the illuminance required to perform a given task, one may simply remove half of the lamps and ballasts from luminaires in the space. However, many spaces can only tolerate a
3-43 Retrofit Technologies reduction in maintained illuminance of about 30%. These spaces are potential candidates for the use of optical reflectors.
An optical reflector is typically a thin aluminum sheet having a mirror-like (specular) finish on one side. A specular reflector is designed to replace a luminaire's existing white (diffuse) reflector. This usually results in raising the efficiency of the luminaire somewhat by directing more of the lamps' lumen output toward the task area. In certain circumstances, a space that is overlighted by, for example, a four-lamp luminaire, will receive adequate illuminance from the same luminaires modified to use two lamps and an optical reflector.
Figure 3-9 Optical Reflectors
Specular and Diffuse Reflection and Luminaire Efficiency
Not all of the light exiting a luminaire is useful light. Some of the light may be absorbed by room surfaces, and other portions may contribute to glare.
The typical fluorescent luminaire uses a white diffuse surface to reflect light out of the fixture to where it can be used. This can result in a portion of the light emitted from the lamps undergoing many reflections before leaving the luminaire. Even if the diffuse surface is a highly reflective 85%, after five reflections the fraction of light remaining will be
(0.85)u(0.85)u(0.85)u(0.85)u(0.85) = 0.44
It follows that if the number of reflections could be minimized, luminaire efficiency would be improved, and more useful light could be obtained from fewer lamps.
The reflectance intensity of light depends on its reflective surface. A luminaire's white, diffuse reflector reflects light into an entire hemisphere. A specular reflector, on the other hand, reflects light into a narrow angle and is therefore easier to control. A luminaire with specular reflecting surfaces can make light exit after only a few reflections, thereby increasing luminaire efficiency.
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Although specular reflectors have been used for many years as original equipment on some HID luminaires and on a few fluorescent luminaires, the retrofit installation of these reflectors (combined with delamping) on fluorescent luminaires has grown rapidly since the energy crisis of the mid-70s. Facility managers have been subjected to a barrage of claims and counter-claims concerning both the virtues and the horrors of the various materials and designs that are used in the industry. In spite of sometimes excessive claims, specular reflectors have been demonstrated to improve luminaire efficiency.
Terminology
A perfect mirror is a purely specular reflector—it reflects an incoming ray out at an angle of reflection that equals the angle of incidence. Some spread will be found in the reflection from actual specular surfaces.
A perfectly diffuse reflector reflects an incoming light ray into all directions in the hemisphere above the reflecting surface. Such a reflector is called a Lambertian surface, and the reflected light obeys the cosine law.
Real materials have a combination of both specular and diffuse reflectance.
The photometric efficiency of a luminaire is a measure of how much of the light that is emitted by the lamps is able to escape absorption in the fixture:
Luminaire Photometric Total Lumens Exiting Fixture
Efficiency = Total Lamp Lumens
Figure 3-10 Specular and Diffuse Surfaces
Materials and Performance
There are three main material systems used to fabricate optical reflectors:
3-45 Retrofit Technologies x anodized aluminum, in which an electro chemical process is applied to provide a thicker oxide coating than would occur naturally. x anodized aluminum with an applied dielectric coating that enhances reflection x aluminum laminated to plastic film that is coated with a silver reflective surface
Installation
Reflectors are usually attached with screws, wing nuts, or specially fabricated metal parts that are attached to the lamp socket bracket. In general, the reflector designer will bend and position the reflector above the lamp to direct light out of the luminaire after as few reflections as possible. Another design goal is to maintain uniform illumination on the diffuser, so as to give the appearance of a full complement of lamps. The benefit of a highly reflective surface can be compromised by poor design or installation.
Prototype Testing
On large projects, you should consider making prototype installations before initiating the entire project. The prototype should consist of at least four luminaires in large spaces. Illuminance measurements should be made at representative locations where the task occurs. A suitable light loss factor (LLF) must be used to estimate the maintained illuminance. To determine what illuminance level must be maintained by the luminaires, measure with and without daylight and task lighting where applicable. Refer to Appendix E on field measurement procedures, particularly for average measurements in an area. Be sure to clean and relamp the original luminaire and age the lamps (at least 100 hours) before making the comparison. Lamp performance is very sensitive to ambient temperature; room conditions should remain constant and the luminaire should warm up for the same amount of time for both tests (at least one hour and preferably eight hours).
Performance Data
Reflector manufacturers make various claims for the reflectance and durability of their products, and offer differing warranties. Instruments that can accurately measure specular reflectance are expensive; so one must rely on testing laboratory data for evaluations of surface reflectances. As with many types of lighting products, it is difficult to ensure that the installed product maintains the originally specified value of reflectance. Also, the design of the reflector affects the efficiency of the retrofit luminaire.
When dealing with contradictory, unintuitive, or surprising claims, the prudent facility manager should request verification of manufacturers' claims by an independent
3-46 Retrofit Technologies testing laboratory, and make sure the test compares products under identical conditions. (see Example 3-).
Rules of Thumb
The results of several studies, in which all variables except for the reflector were held constant, lead to two important rules of thumb:
A four-lamp luminaire modified to utilize two lamps and an optical reflector yields three lamps’ worth of light. Assuming that light output from the original luminaire was measured after being cleaned, and fitted with the identical lamps as used in the retrofit luminaire, the modified light level would be in the range of 60–75% of the original level. The dielectrically coated aluminum and the silver laminates perform at the high end of the range, while anodized aluminum is at the lower end. Part of this increase in efficiency is due to the removal of obstructions (some of the lamps); part is due to the cooler operating temperature of the delamped fixture, which is probably closer to the optimal operating temperature for the lamps, especially for lensed luminaires that tend to operate above optimum temperatures. As shown in Example 3-, using lamps with higher output can compensate so that a two-lamp luminaire can actually produce the same amount of light.
Delamping decreases lighting uniformity by around 15–20% for luminaires with a standard pattern 12 prismatic lens. The illuminance below the luminaire can be nearly as high as in the original fully lamped state due to the imaging power of the reflector, which predominates near the vertical. This change in uniformity may be of no consequence in a particular installation, depending on the average illuminance and the nature and location of the ongoing tasks in the space. The reduction in uniformity may in fact be beneficial in an office environment with VDTs. By decreasing the proportion of light emitted away from the vertical, a reflectorized luminaire should provide less glare than its fully lamped counterpart.
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Example 3-1 Testing an Optical Reflector Manufacturer's Claim
A company claims in its product literature that "you can remove half the lamps while maintaining the same light level." The following discussion and procedure demonstrates how you may verify (or refute) this claim.
The first step is to obtain photometric data. In this case, tests by an independent photometric laboratory showed that the original "seasoned" (but presumably clean) luminaire has a coefficient of utilization (CU) of 0.39. Tests also show that the same luminaire with an optical reflector has a CU of 0.57 (both CUs are chosen for the same variables: RCR=5, and reflectances of 0.70, 0.50, and 0.20 for the ceilings, walls, and floors, respectively).
Next you are ready to use the lumen method (see Appendix D) to calculate the delivered illuminance, as shown in the following table. These calculations are based on one luminaire for each 64 ft2 of floor area.
Reflector Lamp/Ballast Base case Same lamp and T-8 with normal T-8 with high-output System ballasts elect. ballast elect. ballast Lamp F40/CW/ES F40/CW/ES F32T8/8xx F32T8/8xx Lumens/lamp 2650 2650 2950 2950 Lamps/luminaire 4 2 2 2 Ballast Factor 0.87 0.87 0.88 1.28 Coefficient of Utilization 0.39 0.56 0.56 0.56 LLD 0.85 0.85 0.92 0.92 LDD 0.92 0.92 0.92 0.92 Maintained Lamp 2812 2019 2460 3580 Lumens Maintained Illuminance 44 32 38 56 (fc) % Increase (Reduction) (27%) (14%) 27%
As demonstrated above, the validity of the claim depends on the assumptions that were made about the lamps and ballasts that are also part of the retrofit. If the same lamps are kept, then there would be a 27% reduction in maintained illuminance. However, if the lamps and ballasts are also changed (typical), then this can make up for the reduction, especially if high-output electronic ballasts are used that “over drive” lamps.
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Safety
To ensure that the UL rating of the original luminaire is not compromised by the modifications undertaken to install the reflector, make sure that the reflector vendor has a UL listing for the reflector kit. UL listing involves UL inspection of the manufacturing site of the reflector kits, but not of typical installations on clients' premises.
An integral part of the prototype installation should include a careful examination of the reflector kit design from the perspective of safety and future maintenance. The following checklist should ensure a high quality installation. x wiring properly concealed x wiring protected near metal edges x no screw points protruding into wiring channels x socket brackets aligned with fixture body x socket brackets solidly attached x socket firmly attached to bracket x reflectors aligned with fixture axis x reflector easily removable x lamp/reflector clearance > 0.25 inch x lamp replacement not impeded x lens removal not impeded x lens uniformly illuminated without shadows
The prototype installation can also be used to compare the average illuminance before and after modification. This may be used to qualify the reflector by ensuring that a stated minimum percentage of the original (cleaned and relamped) illuminance is obtained after retrofit.
Maintenance
A reflector will only need to be removed to replace a failed ballast, a relatively rare occurrence. Nevertheless, reflectors should still be easy to remove and replace.
Although claims have been made that static electric effects will keep the specular reflector cleaner than the reflector it replaces, it is prudent to assume that the LDD is the same. A reflectorized luminaire will require less maintenance because it has fewer lamps and ballasts. But the reflective surface should be cleaned according to manufacturer's instructions frequently enough to maintain the required light levels. 3-49 Retrofit Technologies
This will probably be more often than before, because the room is no longer overlighted.
Group relamping is another technique that will help maintain the desired light output from a reflectorized luminaire because group relamping ensures that fresh (non- depreciated) lamps are more often in place.
When to Use Reflectors
If you are not changing lamps/ballasts, locate spaces in your building that are overlighted and can tolerate operating at 60–75% of current illuminance. You can determine the existing lighting level using either the lumen method of calculation, or by measurements in a typical space that is cleaned and relamped. If your retrofit includes replacing lamps/ballasts, then you should consider reflectors even in spaces that are not overlighted, as you can choose a lamp/ballast combination that will provide equal or better illumination from the delamped luminaire.
Kits
Retrofits are sufficiently common that reflector manufacturers have standardized the most popular products into “kits.” Kits are generally well-developed products that reduce installation time and cost and combine reflectors or other retrofit technologies with the most often required components to make the retrofit complete.
Take for example the most common retrofit: delamping a 2’x 4’ lens troffer to two lamps, using a combination of a reflector to increase luminaire efficiency and T-8 lamps and electronic ballasts to produce a much lower-wattage fixture and acceptable lighting levels. This retrofit involves these actual steps:
1. Remove lens and set aside to be cleaned and reinstalled (or replaced). 2. Strip out all fixture “guts,” including lamp sockets, socket wires, socket mounting brackets (“bridges”), and ballast. 3. Install new ballast and connect to power source. 4. Install new socket bridges, sockets, and wiring. 5. Connect socket wires to ballast. 6. Install reflector. 7. Install new lamps. 8. Clean and reinstall lens.
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A well designed “kit” usually includes some combination of reflector, socket bridge(s), prewired sockets, and ballast, designed to install quickly into a gutted luminaire, combining most of steps 3, 4, 5, and 6. The technician positions the “kit,” fastens it in position with self drilling “tek” screws, lowers the hinged access, connects power to the ballast, raises the hinged portion back in place, and installs the lens. Labor savings significantly outweighs the additional cost of the kit.
Figure 3-11 Typical Retrofit Kit for 2x4 Troffer
Kits can also be made of retrofits not involving reflectors. One such common kit is designed for replacing two 8-foot F96T12 slimline lamps with four 4-foot lamps and an electronic ballast. This kit is often used for industrial and commercial strip lights, resulting in reduced power, longer lamp life, and lower lamp cost. In some kits the ballast compartment cover is hinged to allow quicker installation by one person.
Even though there are thousands of different fixture designs that are candidates for retrofitting, most of these fixture types have been retrofitted before and the retrofit and reflector companies have developed patterns for them. Now, the features of a kit are readily made into a product designed specifically for the luminaire being retrofitted.
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Table 3-19 Retrofitting Lenses
Lens Type Description Probable Reason For Original Use Typical Coefficient of Utilization (CU)*
Standard Pattern 12 Diagonal pattern of female Generic, most common style 76% conical prisms
Pattern 15 Square pattern female Lens upgrade to improve appearance 72% conical prisms
Pattern 19 Diagonal patterns of male Lens upgrade to improve appearance 72% conical prisms
Pattern 11 Louver lens Upgrade to incorporate appearance of 62% louver with lens performance
Diffuser White sheet acrylic Appearance 57%
Cracked Ice Unpatterned crystals Appearance 63%
*Coefficient of utilization based on a nominal 2x4 size troffer with 4 lamps. The room cavity ratio (RCR) is assumed to be is typical for large rooms. Reflectances are assumed to be 80/50/20 for the ceiling, walls, and floor, respectively.
Lenses
Most lighting lenses are made of high-quality, UV-stable acrylic, and maintain their clarity over many years. Obvious yellowed lenses are inferior products made of styrene or other plastic which is not UV-stable, and should be replaced without question.
Older acrylic lenses, while appearing still fairly “clear,” actually have 15% less transmission and should be replaced every 10 years. New lenses, in addition to recovering dirt depreciation, will give higher lighting levels due to high transmission. The low cost of a replacement lens, in lieu of cleaning, should be considered for every retrofit of older lighting systems. Replacement lenses are available for virtually all fixture types, including troffers, wraparounds, and other styles. At a minimum, replacement of broken lenses should be part of a retrofit program.
Some lenses and most diffusers are inefficient compared to the common “pattern 12” prismatic lens used in most troffers. As a retrofit, consider changing to the everyday pattern 12 prismatic. The specific photometric effects of certain esoteric patterns are often lost on modern lighting situations (except VDT’s—see below). Be especially certain to replace milky white diffusers, “cracked ice,” and other unusual lenses with prismatic lenses in most situations, as fixture efficiency will increase dramatically.
Special Retrofit Lenses
There are a few special lens products that increase luminaire efficiency and effectiveness. The most popular of these products is a lens that can be readily
3-52 Retrofit Technologies recognized by its unique varying patterns of conical and linear lenses. Two-lamp and three-lamp lenses are made, the two-lamp being a popular alternative to reflectors when delamping. As opposed to the reflector retrofit, which improves luminaire efficiency by improving the reflectivity of the luminaire cavity and decreasing the number of inter-reflections, the lens increases luminaire efficiency by being optimized for the luminaire box and lamps. Expect similar results as with reflectors, but expect much different appearance. This type of retrofit lens increases high angle refraction, causing greater perceived brightness and upper wall illumination, therefore increasing glare in many VDT applications.
Changing Lenses for VDT Spaces
Since many retrofits will be for offices and other spaces with computer use, replacing ordinary lenses with products more suited for the task is possible. The following options are available for flat lens troffers (mostly 2’x 4’, 1’x 4’ and 2’x 2’ troffers): x premium versions of traditional conical prism lenses, usually with silver tinting or other means of reducing high angle brightness. Be cautious of some inexpensive (usually thin) lenses which can sag below the luminaire opening, causing excessive glare x special “computer friendly” lenses, generally using many small round “lenses” to direct light into the zone where minimal computer interference can be expected x thin louver panels, often called “egg-crates” or “paracubes,” usually 1/2” thick, consisting of many 1/2” x 1/2” parabolic cells of metalized plastic x thicker louver panels, up to 1½” thick, similar to the above but with cells up to 3”x 3” x full-sized parabolic louvers in chassis designed to sit under existing troffers (the troffer’s lens is removed and the troffer is then lifted up and the louver assembly placed underneath so that the troffer can sit on it)
In general, reflectors can be used with most VDT-compatible louvers, but with varying degrees of success. Reflectors are not compatible with special “VDT friendly” lenses but can be used with premium standard lenses.
Most lens and louver manufacturers can supply photometric data for their products with and without reflectors in a representative luminaire. Use these data in LightPad or other analysis tools to determine whether a reflector should be used with retrofit lenses or louvers. Do not be surprised if the resulting calculation does not recommend a reflector, because the retrofit lens can reduce the illumination so low that a reflector’s light reduction is unacceptable.
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Design Considerations—Lenses and Louvers
In fluorescent lighting systems, the lens or louver affects not only the light quantity and quality, but also key psychological perceptions of the lighting system. When retrofitting these systems, take the following into consideration.
1. Plastic lenses tend to appear utilitarian and “institutional.” Appearance improvements, even minor, will make a space feel more upscale, generally of positive benefit. Louvers are considered a significant quality upgrade.
2. Lenses—especially retrofit lens products—increase high-angle illumination and make a space appear brighter. Louvers tend to decrease upper wall light, creating more dark-appearing or cave-like spaces. The lenses may seem desirable but computer work spaces often are better lighted by the louver.
3. Large-cell louvers and efficient lenses transmit light most efficiently. Small-cell louvers and special lenses produce light less efficiently. When considering a retrofit, use an efficient lens or louver. If inadequate light is produced, consider a reflector in combination with the lens change.
Control Technologies
This section presents information on general control technologies to consider in retrofit applications.
Retrofitting Occupancy Sensors
Occupant sensors may be used to control lighting based on the occupancy of a space. They are good retrofit options when spaces are used intermittently.
Sensor Technology
Devices that switch lights on or off based on detection of motion within a specific room or area are called “occupancy sensors.” There are several different types, each with advantages and features making it more applicable to certain room types and uses.
Occupancy sensors are available in both self-contained devices and as part of more complex systems. Self-contained occupancy sensors are generally wall-mounted in lieu of a standard switch. Devices that require manual activation and devices that turn lights on automatically are available, some offering both options by means of a switch. Devices connected into systems can be wallbox, upper wall, or ceiling mounted, with wiring to the actual switching device (transformer-relay). Systems permit multiple detectors controlling the same lights, covering a larger area with greater sensitivity.
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Table 3-20 Occupancy Sensor Types
Wallbox Sensor Ceiling Sensor x used in place of a standard switch x up to 360° detection x for small rooms like private offices x self-contained or connect to x completely self-contained transformer-relay or large system x x time-out warning interconnect several sensors to cover any sized room x adjustments under plate x adjustments on case x manual on/auto off or switchable x manual/auto on time-out warning
High Wall And Corner Sensors Portable And “Personal” Sensors x often optimal viewing angle x designed to be in front of worker to x especially good for corridors and detect small motions larger rooms x time-out warning x connect to transformer relay or large x adjustments on case system x connects to plug strip x adjustments on case x switches any load, e.g. task light, x time-out warning printer, etc.
There are two primary technologies used in sensor design. Passive infrared (PIR) sensors respond to motion of warm-bodied objects between small visual windows in the sensor’s electric eye. Active ultrasonic sensors emit a field of ultrasound and detect reflections having different frequency, indicating motion by the Doppler effect. PIR sensors are less expensive, but are unable to detect occupants shielded by partitions or other obstructions. Also, there are gaps in coverage for PIR sensors at distances greater than 15–20 ft. Ultrasonic sensors overcome some of these deficiencies, but can pick up false signals such as air movement from HVAC systems or open windows. Some sensors employ both technologies as each has certain advantages over the other.
Primary design considerations for occupancy (motion) sensors
1. Choose a sensor type suitable for the room. The least costly devices—usually wallbox PIR switches—are not sensitive to small motions by an occupant working with his/her back to the sensor, as with a computer. 2. Take furniture and other objects in the room into account.
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3. Choose manual “on” to encourage maximum energy consciousness, but automatic “on” in hallways, rest rooms, common work rooms, etc. as a convenience. 4. There are differing means of time-out warning, and some devices will respond better to an unwanted “off.”
Applying Occupancy Sensors to Existing Buildings
Wallbox Sensors. The easiest sensors to install replace manual wall switches. As compared to a building with only manual switches, wallbox occupancy sensors can be expected to save 10–50% of the energy used by lighting, the actual savings being heavily dependent on building occupancy and use patterns.
Wallbox switch sensors are limited to use in small to medium-sized rooms. Larger rooms need different detectors and often multiple detectors. Wallbox sensors often require three-wire (hot-switched hot-neutral) connections in order to control small loads, such as a single luminaire. Two-wire sensors, which are easier to install, generally require a much larger load.
Sensors with Remote Transformer Relay (“Power Pack”). Sensors to be mounted in optimum ceiling or wall locations and rooms with multiple sensors will generally utilize a power pack containing the transformer to power the sensor’s low-voltage circuits and a relay to switch the lighting power. The power pack is located onto a junction box generally already in place to feed the lights to be controlled. Sometimes a junction box may need to be added or other provisions made. Wiring to the sensor(s) is usually via low-voltage multiconductor cable that can be surface mounted, run in conduit or, if the cable is plenum rated, run exposed above an accessible ceiling.
Sensors Signaling Larger Systems. Sensors can be used to signal larger panel relay systems, building automation systems and energy management systems. Buildings with existing systems of these types might be able to have sensor inputs added as “manual override” zones in lieu of, or in addition to, low-voltage manual switches. New systems being added to buildings generally have special inputs and control features optimized for sensors. As with power-pack sensor applications, wiring between the sensor and the system is typically low-voltage, multiconductor cable.
Personal Workstation Occupancy Sensor. For office workstations and similar applications, a single outlet or plug strip with a remote motion sensor can be used to control task lights, computer peripherals, and space heaters (within the power strip rating, 15 amps for one manufacturer).
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Figure 3-12 Occupancy Sensor/Powerstrip
The motion sensor may be mounted under a shelf facing the occupant, or be free- standing and moved around by the occupant, for instance next to a computer keyboard. The sensor connects to the outlet or power strip with a telephone-type connector cable.
Some models have individual switches in the sensor unit for manual on-off control of the several outlet types. Systems of this type are very easily added to existing workstations with essentially all surface wiring or wiring within the panel system.
Dimming Controls
Many lighting systems can be dimmed, reducing power to save energy and demand. Dimming can occur constantly or during specific periods of use.
Dimming Strategies
Daylighting. Interior (and some exterior) spaces are sufficiently illuminated by natural daylight not to need electric light. However, changes in natural light over the course of the day, as well as constant changes due to weather, would generally cause distracting light switching. Dimming electric lights continuously based on photosensor signals can make the electric lighting system changes unnoticeable to space users.
Adaptation Compensation. Many facilities properly lighted by day will be overlighted by night. For instance, in the center of a tunnel, light is needed by day to allow the driver to see because his/her eyes are adapted for bright daylight. The same tunnel lights could be dimmed considerably by night. Similar opportunities exist in all types of facilities, from hotels to grocery stores.
Lumen Maintenance. Lumen maintenance systems save the excess energy used by new or recently-replaced lighting systems by slightly increasing lighting power over the
3-57 Retrofit Technologies lighting systems’ maintenance period until full power is only used just before maintenance should occur.
Tuning. Many lighting systems provide more light than needed. A minor reduction in lighting (up to about 25%) will not be noticed and for most workers will not reduce productivity. Especially with fluorescent lighting systems, this translates into a direct 25% power and energy reduction.
Manual Dimming. Either in addition to or in lieu of tuning, providing workers with the choice of lighting level can often result in lower energy consumption.
Demand Limiting. A small amount of lighting dimming initiated by a facility-wide management system can be used to help flatten a power demand curve to reduce demand kW costs.
Incandescent. Incandescent lights can be dimmed easily using either standard solid- state dimmers or autotransformer dimmers. Many different types of incandescent dimming systems are available. Because of the low cost and ease of dimming, incandescent dimming is popular in most settings. However, the relationship of incandescent light to power is not linear, and a lamp dimmed to 50% lumen output consumes 78% of its rated energy. Dimming incandescent lighting to save energy thus has extremely modest potential and should be considered only after other options have been evaluated.
Fluorescent. Full-size, U-bent, and compact fluorescent lamps can be dimmed effectively and with significant potential for energy savings. Methods of dimming include: x electronic ballast with internal dimming circuits whose action is controlled by an external signal (This is by far the most recommended method.) x dimming magnetic ballast whose input power is regulated by a dimmer similar to an incandescent dimmer x non-dimming magnetic ballast whose input power is regulated by a special type of dimmer or an autotransformer x reduced light output at fixed amounts using stepped ballasts or devices for magnetic ballasts which modify the impedance of the lamp arc circuit (power reducers or current limiters)
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Figure 3-13 Effectiveness of Dimmers at Saving Energy
Fluorescent light and power are almost linear between about 100% and 20% for electronic ballast dimming. Below 20%, decreasing light reduces power less. As a result, most electronic dimming ballasts have a minimum of 10–20%. However, some electronic ballasts intended for “architectural” dimming applications can dim to as low as 1% or less of rated lamp light without flickering.
Other methods of fluorescent lamp dimming, especially any method using ordinary magnetic ballasts, should be pursued carefully as reduced energy efficiency, short lamp life and limited dimming capabilities are common risks.
High Intensity Discharge (HID)
Of the modern light sources, HID lamps are probably the most expensive and least desirable to dim. Dimming impacts proper lamp arc temperature and pressure, which causes efficacy to drop and color to shift. Short lamp life can also result.
However, there are a few specific systems designed for HID dimming applications which, in addition to minimizing these problems, provide meaningful energy savings with few drawbacks. The key to their use is limiting applications to spaces where color rendition is not important, such as industrial, warehousing, and transit facilities.
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Re-Wiring
Most dimming methods will require the addition of wires to carry the control signals, as well as the control generating signals from photosensors and other devices. Recent developments in electronic ballast design allow for dimming to be controlled using existing two-wire circuits by replacing an existing wall switch with an incandescent dimmer. Another product uses low-voltage cables exclusively for controls, permitting existing power wiring to be left intact.
Timers and Time Clocks
Timers are devices that activate lights for predictable periods of time. Although simple in concept and insensitive to occupancy, timers serve a valuable function by assuring an absolute cessation of lighting operation without further user input. Time clocks are traditional scheduling devices for energizing lights for predetermined periods on a regular basis. Both cost less and are easier to install than other control devices.
Mechanical Timers
Mechanical timers utilize a wound spring to measure time and open the circuit after a predetermined period. The range of the device (e.g. 0–15 minutes) is fixed by the switch mechanics. Rating is usually 15 amps at 120 volts.
Figure 3-14 Mechanical Twist Timer
Electronic Timers
Electronic timers allow changing of the time period and generally have tap-on control. In addition to more modern appearance and tactile response than mechanical timers,
3-60 Retrofit Technologies electronic timers have an accurate electronic time readout and optional time-out warning.
Figure 3-15 Electronic Touch Timer
Programmable “Time Clocks”
The redundant expression “time clock” has been used for decades to describe electric clock mechanisms with mechanical dials having trippers to open or close a mechanical air-gap switch. More recently, electronic devices have become popular as well.
A mechanical time switch is a device having an integral 120-volt motor-operated clock and an air gap switch operated by trippers attached to the clock face. Portable plug-in devices as well as wall box mounted devices are sold. Larger devices enclosed in interior and exterior NEMA boxes are also made. Typical mechanical devices generally can control two 40-amp circuits. Electronic clock package units are now available controlling up to eight independent 20-amp circuits each having different time schedules. Inexpensive mechanical devices are invariably 24-hour schedule devices, but the larger mechanical units and most electronic units can also include such features as 7-day calendar clocks and “astronomical” dials, clocks which are (theoretically) able to compensate for the change of seasons.
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Figure 3-16 Programmable Time Clock
Applying Timers and Time Clocks to Existing Buildings
Timers generally replace wall switches directly. Time clocks are generally added in the power circuit feeding the lights, often in a utility location such as an electric closet or mechanical room. Because time clocks seldom have an associated wall switch or other need for user access, installing time clocks is generally easy and often occurs adjacent to the panel feeding the lights.
Powerline Carrier Controls
Despite the continuing increase in the amount and type of high-harmonic content loads in buildings, makers of powerline carrier systems believe that modern digital communications technology can overcome the problems of prior analog designs and permit widespread use of powerline carriers in most buildings. Products are presently under development that show definite promise. Until these systems are available, knowledgeable designers can still consider powerline carrier systems, analog or digital, provided specific considerations are made:
1. Loads that generate harmonics or other spurious signals in the band(s) used by the system need to be isolated and filtered or removed. For instance, some “wireless intercom” systems use powerline communications and can effectively block the powerline medium to the control signals. 2. Loads which “short out” high frequency signals may need to be isolated or changed. Power factor correction capacitors and certain very low harmonic electronic ballasts diminish the control signal, making it difficult to be received down line. 3. Amplifiers, signal repeaters, and coupling bridges need to be added throughout the system.
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Photocells
“Photocells” are switching devices to turn lights on or off according to the amount of light striking the sensor (photocell) surface. Most photocells are designed for switching outdoor lighting at dawn and dusk. A hysteresis and time delay circuit is built in to prevent nuisance switching and “chattering” when incident light is at or near the switching point. Most photocells are not adjustable. Outdoor photocells can be mounted onto fixtures or can be separately mounted on a building roof or other location.
There are a few photocells designed for indoor use. They generally have some sort of adjustment, usually mechanical, although there are an increasing number of devices with electronic adjustments. Many such devices are part of an occupancy sensor designed for ceiling or wallbox use.
Photocells are designed to be rugged, reliable, low cost, and fairly uniform in performance. There are very few options. All photocells are designed for open-loop applications; so they must not sense the light created by the fixtures being controlled.
Photosensors
Photosensors are devices that create continuously varying analog outputs designed to interface with fluorescent dimming electronic ballasts in energy management applications. Most photosensors have adjustments similar to occupancy sensors, including time delay, response speed, and sensitivity.
Most photosensors were made and sold as part of a system by the manufacturer of the dimming ballast. Photosensors sold as part of a system may communicate with the dimming ballasts in a number of ways, including 0–10 VDC analog signal, pulse-width (duty cycle) modulation and AC wave conduction angle.
There are, however, a growing number of generic photosensors. These photosensors create analog signals compatible with electronic ballasts that utilize a 0–10 VDC signal to determine light output.
Considerations of photosensor applications include: x Setting sensitivity includes setting the low end and high end (range), which can be difficult and require considerable patience. x The sensor generally must be protected from direct viewing of the sun and bright sky. x The sensor looks at the light being created by the luminaires it controls and should be located to look at the task area or otherwise follow manufacturer’s installation
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recommendations, avoiding looking at non-task areas and other parts of the space that can create misleading or incorrect signals. x Sensor response can be affected by the number of ballasts connected to it. x Sensors can be sensitive to bright areas within the zone, such as a person entering the space wearing white clothing or the work surface being covered by a large piece of paper. The bright zone sensitivity of photosensors on the market varies widely.
To take full advantage of the photoelectric control strategies of daylighting, lumen maintenance and adaptation compensation, system performance including both the photosensor(s) and ballast(s) will probably best be optimized by a system from a single source supplier who can best match products, make critical adjustments, and even add components. Many manufacturers are taking this point of view, and their ballasts are generally not for sale or intended to be used with generic photosensors. But such systems can limit competition and increase cost, especially for small projects.
On the other hand, now that all of the major manufacturers of electronic ballasts are offering reliable, competitively priced dimming ballasts with at least a 20–100% dimming range, the race is on to develop low cost, high performance generic photosensors. The competition between the two viewpoints is expected to be fierce.
Latching Switches
A “sentry” switch is an electro-mechanical latching relay with toggle switch activation. It is designed to replace ordinary toggle switches and appears similar in appearance.
The sentry switch operates as follows: by activating the switch, a latching relay circuit in the switch body is closed, providing continuous power to lights. Deactivating the switch manually results in lights being extinguished, as the user would expect. But the key to the sentry switch’s importance is that, if power is interrupted to it, the switch resets to the “off” position automatically.
Sentry switches permit the use of relays and contactors in electrical closets and other remote locations to “sweep” off building power by briefly turning lighting circuits off, then on. The sentry switches reset to “off,” and those needing lights can simply turn their lights back on without all lights on the circuit being energized.
Sentry switches are the least expensive way of retrofitting an existing building with switches in every room to an automatic time-of-day shut-off control having maximum savings. The interruption to workers may or may not be acceptable.
3-64 4 LIGHTING SYSTEM TYPES
This chapter addresses common retrofit opportunities for general lighting system types. Lighting system types are organized in three general categories: commercial, industrial, and outdoor. The table below expands on these general categories.
For each of these categories, we will include a description, illustrations, and a discussion of retrofit options with a guidelines for assessing the options.
General Commercial
General Commercial Lighting Systems
Commercial lighting includes the lighting systems used in office buildings, institutions, stores, schools, and all other nonindustrial, nonresidential buildings. This lighting constitutes almost 50% of the electric lighting load in the United States. Most of these lighting systems were based on the F40 fluorescent lamp; and while their designs and materials have evolved over the last 50 years, even the most modern products bear considerable resemblance to the oldest fluorescent products. The remainder of commercial lighting systems tend to be based on incandescent lighting and include common styles such as downlights and many different decorative fixtures.
Because most commercial general lighting is based on the four-foot T-12 lamp and its relatives, a majority of these lighting systems can be retrofit easily and cost-effectively. Other lighting systems, such as retail lighting systems, also enjoy the potential for impressive savings and payback.
For retrofitting, commercial lighting is the largest opportunity. The most common retrofits include T-8 lamp and electronic ballast conversions, which, due to their vast popularity and success, have resulted in extremely low material costs and the probability of cost-effectiveness in most applications. Similarly, conversions of incandescent luminaires to compact fluorescent have also become quite cost-effective as volume has driven down prices and encouraged the development of clever labor- saving products and procedures. The vast number of retrofits of these lighting systems types assures successful results in most situations.
4-1 Lighting System Types
Table 4-1 Lighting System Types
Category Lighting System Type Notes General Commercial Fluorescent Troffers Probably the most common Downlights Very common, also wallwashers, accent lights, etc. Fluorescent (non-troffers) Wrap-arounds, direct/indirect, pendant-mounted, cove lights, undershelf, medical Decorative and Utility Lighting Chandeliers, pendants, sconces, table, and floor lamps, etc. Exit Signs Track Lighting Industrial Fluorescent High Bay Low Bay Vaportight Watertight Special Purposes/Environments Prisons, caustic, explosive, etc. Outdoor Roadway and Parking Lots Floodlights Security Decorative Landscaping
Fluorescent Troffers
The fluorescent "troffer" is the most common type of commercial lighting system. Most troffers utilize some form of flat plastic or glass "lens" or diffuser as the shielding and refracting medium. In some cases, small-cell louver panels, sometimes called "egg- crate" or "paracube" louvers, have been installed in place of the lens. After about 1980, the larger "parabolic" louvered fixtures became increasingly popular (see separate standard). Still, the lens troffer is the commonest recessed fluorescent lighting product type manufactured.
Troffer lighting systems are excellent lighting retrofit opportunities. Without changing illumination levels, lighting power demand and energy can often be reduced up to 40%; with an acceptable lighting level reduction, power demand and energy savings can be 60% or more. A wide range of products is available to make conversions with acceptable payback periods.
General Information
Support. The troffer is designed to lay into a tee-bar acoustic tile suspended ceiling system, making it an integral component of the most inexpensive complete ceiling- lighting-HVAC system used in commercial construction today. There are a number of
4-2 Lighting System Types different standard grids, each having specific dimensions and for which small but important differences in troffer dimensions are apparent. Independent structural suspension is required in California and other locations, particularly for earthquake resistance.
HVAC Coupling. Troffers can be sealed boxes ("static") or can serve as part of the building's HVAC delivery system. x Heat Extract troffers allow return air to be removed through the troffer into a return ceiling plenum, especially by passing air past the lamps. Heat extraction helps cool the fluorescent lamps to a near-optimum temperature, thereby generating maximum light. Heat extraction was extremely important for four-lamp T-12 troffers but is relatively unimportant in electronic T-8 systems. x Air Supply and/or Air Return troffers employ a thin air slot all around the lens. The slot is connected to an HVAC system "boot" that in turn is connected to either a supply or return duct. x Some troffers are shipped with all options and certain field adjustments allow the luminaire to assume any of these configurations.
Shielding Media (Lenses and Louvers). The most common shielding medium is a flat plastic panel comprised of small prisms, often called a prismatic lens. Although many different types have been developed, the most common is the "pattern 12," a checkerboard pattern of conical prisms. Pattern numbers were assigned by KSH (now ICI Acrylics), a leading developer of lighting media.
Other shielding media include: x Other prismatic lens types, including square prisms, linear prisms, etc. Some of these lenses may be tinted, which reduces brightness but reduces glare as well. x Egg-crate louvers, either white or metalized up to 3/4" thick x Flat and drop milky plastic diffusers x Special types of lenses such as "bubble" elements and non-homogeneous prismatic patterns x Multilayer polarizing panels
Lens thickness affects appearance and sag. The industry standard for the pattern 12 lens is .110" thick, although specifiers prefer .125" and cheap lenses are .100". Lenses should be made of lighting-grade, UV-stabilized virgin acrylic. Yellowing of lenses or plastic louvers indicates use of polystyrene or other non–UV-stable materials.
The lens or louver is usually held in a door with hinges on one long side to allow access to the lamps. Doors may be steel or aluminum, flat or regressed, and butt-joined or
4-3 Lighting System Types mitered in the corners. In some very inexpensive luminaires, the lens may be enclosed in a lightweight frame that utilizes a lift-and-shift access to the lamps.
Internal Reflecting Surfaces. Most troffers employ baked white enamel paint on the interior reflecting surfaces. White enamel degrades over time, losing reflectivity in the process. Enamel paint is about 80–85% total reflectivity. Porcelain was also used in premium products, but is not significantly different from white enamel paint. Current products may use polyester powder coat paint with 90% or higher total reflectivity and better UV stability.
Lamps and Ballasts. Most troffers were designed for F40T12 rapid start fluorescent lamps, including the 2'x 4', 1'x 4', 4'x 4', 20"x 4', and some 5' long units. The 2'x 2' troffers were designed either for the FB40T12 U-lamps or the F20T12 straight lamps. The 3'x 3' units usually used F30T12 lamps, although there were also some using diagonal F40T12 lamps. Some new fixtures (and those retrofit) may have FO32 (T-8) lamps. Rarely, one may find slimline (F48T12) or high output (F48T12/HO) lamps.
Ballasts are located in compartments, generally accessible from the interior of the luminaire. However, some products may have outboard ballast compartments, especially to one side to make for a shallower troffer. Existing fixtures in most of the United States originally installed prior to 1990 (prior to 1982 in California) may be assumed to have standard or non-energy saving ballasts as original equipment.
Retrofit Opportunities
General Considerations. The ability to reduce energy in troffer retrofits is a function of reducing power as much as reasonably possible. Consider all of the following in selecting a retrofit program: x General layout (square feet per fixture). The coverage area per luminaire is critical in determining design lighting level, new lighting level, and any opportunities for intentional lighting level reduction. x Room surface finishes. Rooms with dark surfaces must be lightened whenever possible, including ceiling tile replacement where existing tiles are soiled or not fairly white. Dark finishes can act as light absorbers capable of causing 20–30% light level reduction in smaller rooms as compared to lighter finishes. Recovering lighting level by painting rooms or replacing ceiling tiles allows as much as 25% less lighting power than a dark room and is a critical potential energy conserving element of a DSM program. x Lighting level. Reduce lighting levels to appropriate levels if the space is overlighted.
Reflectors. The most widely advertised retrofit product is a new internal reflecting surface for the luminaire. Although much of the advertising is technically misleading,
4-4 Lighting System Types retrofit reflecting surfaces can be effective in certain luminaires when combined with a power reduction strategy such as delamping and/or T-8 lamp and electronic ballast conversion. There are three primary retrofit reflector types: x specular (shiny) high-purity aluminum, having a total reflectivity of 88–92%, and formed into an imaging faceted reflecting surface x specular silver on substrate, having a total reflectivity of as high as 94%, also formed into an imaging faceted reflecting surface x white polyester powder coat paint on steel or aluminum, having a total reflectivity of about 90%, formed into a simple semi-diffuse reflecting surface
Specular imaging reflectors are designed to reflect mirror images of the lamp's sides directly onto the lens, thereby eliminating multiple interior bounces for each light ray. In deep fixtures (aperture to reflecting surface 4.5" or greater) significant efficiency benefits are achieved through the use of imaging reflectors regardless of the condition of the original reflecting surface. In shallow fixtures, especially with well-maintained or new white painted reflecting surfaces, the benefits of imaging are minor.
Silver specular reflectors should only be used when supplied by a major company and backed by a 10-year warranty. High purity premium specular aluminum reflectors with 20–25 year warranties are generally preferred due to lower cost. Specular imaging reflectors should only be used in deep troffers, or in conjunction with metalized egg- crate or "paracube" louvers. White polyester powdercoat reflectors may be used in situations where a shallower luminaire has an aged or deteriorated reflecting surface.
Lenses and Louvers. Any lens or louver appearing brown or yellow should be replaced. This discoloration is a sign of UV degradation and/or age, and reveals a surface whose efficiency has fallen by 30–60%. Also, any lens over 10 years old should also be replaced; although not apparent, its transmitting efficiency has also degraded by as much as 15%. In most cases, a new pattern 12 acrylic prismatic lens will be adequate.
It is possible to retrofit lens luminaires in VDT workspaces to meet modern computer screen standards. In most troffers, this upgrade occurs with either: x one of several acrylic lens products designed for VDT applications, with or without white powder coat reflector retrofit; or x a paracube louver with or without specular imaging reflector retrofit
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Table 4-2 Recommended Illumination Levels
Space Type Recommended Illumination Level1 Measurement Conditions
General Office Space 60 fc empty room, initial
Computer Office Space 40 fc empty room, initial (task lighting should be added)
Conference Rooms, Lobbies 40 fc empty room, initial
Classrooms 60 fc empty room, initial
Major Hallways, Corridors 20 fc empty room, initial
Grocery Stores 75 fc empty room, maintained2
Industrial/Commercial Work Areas 50 fc empty room, initial (task lighting should be considered)
Retail Stores with Separate Track or Display 40-60 fc empty room, initial Lighting (display lighting is assumed)
1 Maintained illumination will be 15 to 20% lower than the initial illumination recommendations in this column (except for groceries)
2 Maintained lighting level is a highly debatable issue, especially in grocery markets where lamp life can exceed 30,000 hours. Because fluorescent lamp lumen depreciation is a function of operating hours and not number of starts or average hours per start, it is tempting for the grocer to leave lamps in place as long as possible. Designing for a minimum maintained lighting level assuming such lamp life will result in systems using excessive initial energy. Unless lumen maintenance dimming equipment is employed, it is recommended that an economic break-point be determined as a function of lamp and relamping cost as compared to excessive energy consumption cost.
Since VDT-compatible lighting should also be at a slightly lower illumination level than standard office lighting, often lighting systems can be upgraded within the economics of a DSM retrofit project. However, even if the economics do not work out, many clients will consider paying extra for the upgrade.
Lamps and Ballasts. Since most troffers employ T-12 bi-pin lamps, there is almost always a direct T-8 substitute which will fit the existing sockets (called "tombstones"). Tombstones should be replaced if they are relocated or if they appear cracked or otherwise broken; otherwise, replacing tombstones is probably not necessary. The number and type of T-8 lamp should be determined as set forth below.
When converting from T-12 to T-8 lamps, conversion to electronic ballasts is standard procedure. (see the Retrofit Technologies chapter.) The number of lamps operated per ballast should be maximized, replace two two-lamp ballasts with a single four-lamp ballast. However, adjustments should be considered to accommodate switching, such as separate daylighted zone controls or multilevel (master-slave) switching.
Occasionally, converting from a U-bent T-12 lamp to straight FO17T8 lamps makes sense. Kits that include the new sockets, ballast covers and wireways are standard products with or without a reflector.
4-6 Lighting System Types
Delamping. Many of the best retrofit programs involve some form of delamping to reduce power. This is in part possible because older lighting systems tend to be overdesigned by modern standards. For example, one of the most popular lighting layouts employs four-lamp F40T12/ES lens troffers on 8'x 8' spacing. Using conventional cool white energy-saving lamps and magnetic energy-saving ballasts, this system produces about 85 initial foot-candles, average, in the average private office and about 105 initial foot-candles in an open office area at 2.25 watts per square foot. Part of the opportunity for energy savings is to reduce the lighting level and its power through delamping.
However, delamping does not necessarily imply the use of retrofit reflectors. In many cases, delamping and relocating the tombstones, combined with T-8 /electronic ballast conversion, luminaire cleaning, and a new lens, will provide satisfactory results.
Choosing a Retrofit Package. The best retrofit will be the one providing necessary illumination with the best payback on the investment (including the benefit of the utility rebate, if any).
If luminaires can be moved around easily and without concern for asbestos, structural integrity, HVAC connection, or other limitations, assuming ceilings up to 10 feet high, a general program of two-lamp luminaires on 8' x 8' centers is recommended. This allows a variety of ballasts, lenses, and reflecting media to be used to accomplish the best possible result. However, it is generally anticipated that luminaire relocation will not be feasible for most projects.
Therefore, the following selection process is recommended:
1. Establish the desired foot-candle level, which can vary from room to room. 2. Based on the luminaires in place, select options that provide the desired initial foot- candle level, plus-or-minus 10%. There will be a number of options in many cases. 3. Determine the cost, energy savings, rebate, and payback for each option. Some options use less energy than others, but probably cost more. Make certain to obtain prices from corporate purchasing on key items like electronic ballasts, T-8 lamps, high performance lenses, and other standard components. At this time, reflectors are to be purchased locally. 4. Select the most desirable option under the project's circumstances. This will be an acceptable solution for all parties.
Incandescent Downlights
Downlights are the most common family of architectural luminaires, including wallwashers and accent lights. Often called “cans” or “tophats,” downlights are designed to throw light downward from the ceiling. Most downlights are round and 4-7 Lighting System Types are recessed into gypsum wallboard, acoustical tile, or other types of finished ceilings. However, there are also square downlights and surface-mounted types. The most common uses of downlights include lobbies, corridors, meeting and conference rooms, auditoriums, theaters, and highly finished spaces such as executive office areas, restaurants, or hotels.
The vast majority of downlights use incandescent lamps. However, there are a small number of HID downlights in use, and a growing number of compact fluorescent downlights, especially in new construction in states with significant energy codes. Both the incandescent and HID downlights offer retrofit opportunities.
General Information
Types of Downlights. To assess the retrofit opportunity properly, it is important to understand the types of downlights, which vary significantly by application and optics. x Open “R” lamp with baffle trim. Estimated to be the most commonly occurring downlight, and used for general illumination in many building types, the black baffle R lamp downlight is used for general illumination only. The objective of the black baffle is to reduce glare. When used for general illumination in ceilings less than 12 feet, it can usually be retrofitted with hardwired or screw-in compact fluorescents as described later in this handbook. x PAR lamp black baffle. Similar to open R lamps, PAR lamps are generally installed in higher ceilings. The candlepower of the PAR-38 lamp is used for general illumination in higher ceilings, typically above 12 feet and perhaps as high as 20 feet. The largest lamp is usually Q250/PAR-38. Compact fluorescent or HID retrofits may be appropriate, but will depend on the application. x R and PAR downlights, multiplier cone. The polished parabolically shaped multiplier cone improves the efficiency of the fixture while maintaining reasonable glare control. These lamps can be retrofit with HID or compact fluorescent hardwired versions, with the proper retrofit being very application-dependent. If the cone is black or dark bronze specular aluminum, the fixture was probably selected for a special application that should be identified. x R and PAR lamp adjustable accent lights. Designed to look like fixed downlights, these are adjustable accent lights in which the lamp’s pitch and rotation can be changed to project a beam onto a specific item. In addition to using some of the common 120V PAR and R lamps, adjustable accent lights are often equipped with low-voltage lamps, such as the PAR-36, PAR-56, or MR-16. When a low-voltage lamp is used, the transformer is usually on the fixture chassis. In general, these are relatively poor retrofit opportunities, with few if any suitable compact fluorescent conversions. However, there may be specific instances where changing the inherent technology
4-8 Lighting System Types
might be appropriate, such as retrofitting a high-wattage incandescent with an HID lamp. These situations will be very application-dependent. x Open “A” lamp downlights. “A” lamp downlights are almost always used for general illumination. Although the reflecting surface behind them is generally polished alzak (aluminum), some inexpensive variations use white paint. There is no lens below the lamps. The trim may be a multiplier cone extension of the reflector or a short black baffle. Open A luminaires are particularly well-suited to compact fluorescent conversions. x Ellipsoidal downlights. Ellipsoidal downlights operate using the principle of an elliptical reflector; the light generated by the lamp is refocused and the beams of light cross at a point out in front of the luminaire. In this way, all the light is refocused through a small aperture and into the space. Ellipsoidal luminaires are easily recognized, because they have a large-diameter reflector above the lamp but a relatively small hole in the ceiling. The trim may be either a black baffle or a multiplier (polished) cone. Because of the manner in which the elliptical optical system works, the ellipsoidals do not lend themselves to compact fluorescent retrofits. Higher powered A-lamp ellipsoidals may be converted to HID, but quartz lamp ellipsoidals have no straightforward conversions. In general, if a retrofit is suitable (and usually it is not), it will be necessary to remove the entire ellipsoidal reflector and convert the luminaire completely to open compact fluorescent or HID. x Lens Downlights. For general interior illumination, lens downlights were more popular in the 50s and 60s, giving way to the open downlight in the 70s and later. However, lens downlights are still used in new construction, especially in wet spaces and outdoors. (Note: All metal halide downlights require a lens due to the potential for explosive lamp failure.) Because in most cases the optical properties of the luminaire are determined largely by the lens, which may either be prismatic, fresnel, or diffuser, most lens downlights use A lamps. Although lens downlights usually lend themselves well to direct compact fluorescent or HID conversions, it may also be possible to update the appearance of the luminaire by installing an all new open compact fluorescent or HID kit. Because open luminaires are generally more efficient than lens luminaires, additional energy savings can often be realized with this type of conversion. x Low-voltage fixed downlights. The use of MR-16s and other low-voltage lamps in fixed downlights is rare but occasional. Situations where these lamps are used are almost exclusively “high-end” office buildings and special applications like auditoria. Retrofit opportunities exist, but are usually not very attractive. x Compact fluorescent downlights—horizontal burning lamps. Downlights with two horizontal burning compact fluorescent lamps became popular in the 1980s. Because of the efficacy of the fluorescent source, retrofit opportunities are very limited.
4-9 Lighting System Types
Related Architectural Luminaires. x Eyelid wallwashers. Eyelid wallwashers are generally found with many different types of lamps, including A lamps, R lamps, and even MR-16 lamps. They have limited retrofit opportunities, largely because the compact fluorescent lamps generally lack sufficient lumens to do adequate wall washing. An HID retrofit may be sensible in situations having long burning hours. x Recessed spread-lens wallwashers. These are high-quality luminaires and require high- quality retrofits to achieve decent performance. Luminaires using 300-watt R40 and high-wattage PAR lamps (typically Q250/PAR-38) might be retrofitted with 70-watt metal halide PAR lamps to achieve relatively similar performance, but the retrofit will involve the installation of the metal halide ballast, new socket, and high- impulse voltage wiring. As an alternative, some of these fixtures might be re- equipped with compact fluorescent assemblies designed for a similar optical system; these are very product-specific and would require a minimum of two 26- watt lamps to achieve similar performance. x Downlight wallwashers. These fixtures have similar retrofit problems to the eyelid wallwasher. Most compact fluorescent sources have inadequate lumen output; HID retrofits would only be appropriate in spaces having long hours of operation with infrequent switching and no dimming. x Eyeballs. Eyeball luminaires are not particularly attractive, but often used as a cross between a wallwasher and an accent light. Depending upon the light source, a retrofit might be attempted; however, the proper retrofit will be very application- dependent.
Ratings and Listings. In the 1978 National Electrical Code, the first new requirements were introduced to make thermal protection mandatory in residential downlights. Called type “T” (thermally protected), most manufacturers included this feature in all products, even though the Code did not require it for commercial suspended ceilings.
Subsequently, the Code also introduced requirements for “IP” (insulation protected) and “IC” (insulated ceiling) downlights for, again, primarily residential construction. The type “IP” is now required to prevent inappropriate applications of standard luminaires into direct contact with insulation. The type “IC” is required for situations where direct contact with insulation is necessary, especially in energy-efficient residential construction. However, most fixtures in commercial applications either predate the standards, or are type “S” (suspended ceiling—commercial only) or type “T.”
The thermal protector is usually inside the can near the socket. It is wired in series with the lamp and opens if overheated. The insulation detector, usually a thick black rod about 3” long, is often mounted to the junction box. It is actually a heating coil and contact, with the heater always energized. The contact is in series with the lamp. If 4-10 Lighting System Types insulation is packed around the detector, the contact mechanism will overheat and disconnect the lamp.
Damp and Wet Labels. UL and other testing laboratories list downlights for indoor, damp locations (which are sheltered from direct rain or spray but can be outdoors), wet locations (indoors or out, direct spray), and a special label for use near baths and spas. The label is often a function of the trim. It is important to use the proper trim with appropriate listing relative to the application to meet code.
Retrofits and Code. Since most retrofits replace a very hot incandescent lamp with a cooler-operating and lower-wattage fluorescent or HID, there is little concern over the thermal properties of the downlight. Most retrofits will have only desirable impacts.
However, it is important to consider all aspects of the code when retrofitting. Most retrofit kits are UL listed for general purpose applications and are damp labeled. There are no known wet labeled compact fluorescent retrofits; so be especially aware of potential code problems in outdoor luminaires and indoor wet areas like shower rooms.
Retrofit Opportunities
Many—if not most—incandescent downlights can be retrofitted with compact fluorescent or HID lamps. In fact, retrofits of downlights are extremely common and the most visible retrofits to be found. Replacing 3-4 watts of incandescent with 1 watt of fluorescent is a good rule of thumb; the challenge is to make the result aesthetically acceptable.
Among the many options:
1. Medium-based screw-in compact fluorescent lamps are still the least costly way to convert a simple downlight. The latest modular adapters, in which the compact fluorescent lamp is a replaceable quad or triple tube pin-based lamp, also means the retrofit will have good life-cycle economics, too. In most cases, the adapter includes a reflector optimized for the compact fluorescent lamp. These adapters are best suited for downlights in low ceilings (10’ high or less) since they are limited in watts (18-26 maximum) and beamspread (usually 60-80q or more). Most adapters are suitably listed for dry or damp locations. 2. There are quite a few conversion kits in which a ballast and compact fluorescent socket are installed in place of the existing incandescent socket. These kits either convert the existing downlight reflector to a true compact fluorescent downlight, or replace the reflector completely with one optimized for a compact fluorescent. Because these options are more optically precise, higher wattages (32-42 watts) and narrow beams (30-40q) permit use in higher ceilings. Most kits are listed for suitable dry and damp locations, and some might also be suitable for wet location fixtures.
4-11 Lighting System Types
3. Likewise, some high wattage incandescent downlights can be retrofitted with a suitable metal halide lamp by adding a ballast, new socket and some new wiring. However, these conversions are uncommon and a listed kit of parts may not be available. 4. Outdoor applications for compact fluorescent conversions, once thought to be limited, have been increased by the advent of the low temperature electronic ballast.
5. Introduced in 1996, electronic ballasts that can be dimmed using ordinary incandescent phase angle dimming (two wire standard circuit) permit compact fluorescent retrofits in situations where an incandescent retrofit might previously have been avoided due to the need to dim. Keep in mind that compact fluorescents do not dim as low and that lamp color may shift differently than incandescent at low light settings.
Fluorescent (non-troffers)
Other than troffers, most fluorescent luminaires used in a wide variety of building types fall into the general categories of “commercial” or “industrial” lighting. These categories cover everything from strip lights to shop lights, including many common types and quite a few special purpose luminaires. Like troffers, most industrial and commercial fluorescents offer energy-efficient retrofit opportunities ranging from fair to excellent depending on the utility rate and the hours of operations.
General Information
Strip Lights. Strip lights or “channels” are the most basic of fluorescent luminaires, but have a surprising number of uses. Like bare incandescent lamps, a strip light can be used to produce cheap general illumination, as long as efficiency and glare control are not important. But often, the strip light is used in unique situations, such as inside cabinets or cases, in coves or valances, behind Plexiglas sign panels, or other applications where a “line of light” is needed.
Commercial Wraparounds. Wraparounds are relatively low-cost fluorescents designed to have a finished appearance whether surface-mounted or suspended by pendants. The luminaire is essentially a strip light with a U-shaped diffuser or lens surrounding the lamp on three sides, producing some uplight as well as widely distributed downlight. One- and two-lamp “wraps” are used in corridors, stairs, and a wide variety of general lighting and utility applications. Four-lamp wraps are often used for the office and retail lighting, as well as some types of “clean” industrial lighting.
Supermarket Trough Luminaires. While markets use strip lights, industrials, or troffers, many designs prefer shallow “trough” luminaires. In retail lighting, an exposed lamp is important both for economy and to convey to the customer that the store is “open.” The trough provides an improvement in the store appearance and visual comfort
4-12 Lighting System Types without losing either of these important benefits. Moreover, the trough is an efficient lighting system, almost as high as an industrial system and far more efficient than lensed or louvered recessed lighting.
Task Lighting. Ranging from bare strips to sophisticated luminaires with special lenses, task lights are employed in homes, offices, hospitals, shops, and most other building types. The most common installation is underneath overhead cabinets in office workstations and over vanity and counter tops in labs, kitchens, exam rooms, and many other types of facilities.
Retrofit Opportunities
Lamps and Ballasts. The primary retrofit for fluorescent luminaires in these categories is to replace standard ballasts with electronic, and often, convert T-12 lamp systems to T-8. Unlike troffer lighting, many of these luminaires were originally equipped with 8’ lamps and with slimline or high output (HO) T-12 lamps operating from standard magnetic ballasts. It is also important to note that 8’ T-12 systems can be favorably retrofitted with electronic ballasts (and for maximum light, RE8xx lamps) without needing to employ T-8 lamps. For most situations either standard FO32 (F32T8) lamps or 8’ T-8 lamps (standard or high output) can be suitable retrofits. In the simplest of retrofits, it is desirable to replace the existing maintained lamp lumens with an equal amount.
Reflectors and Delamping. Both specular imaging and high reflectivity white reflectors can be used to improve lighting systems’ performance, usually permitting delamping or technology changes with fewer lamp lumens. However, few industrial and commercial fluorescent luminaires other than troffers can benefit from this. The following chart shows some luminaire types, approximate efficiencies, and approximate efficiency and coefficient of utilization (CU) gains.
Open fluorescent fixtures are already so efficient that there is little opportunity to increase illumination much; to gain a meaningful increase will require specular reflectors that may create objectionable discomfort glare. Shielded fluorescent luminaires—such as wraparounds and washdowns—would suffer drastic changes in light distribution if reflectors were used. Sometimes the best retrofit might be a different luminaire type, such as an open industrial.
Strip Lights. In addition to basic technology changes, consider the following retrofits for strip lights: x General lighting. Adding a symmetrical reflector can increase the coefficient of utilization (CU) of strip light systems, especially when the strips are suspended from a ceiling or if the ceiling has poor reflectance. The reflector can be white, specular, or for a “design” appearance, white perforated to allow a little uplight (see
4-13 Lighting System Types
the discussion of small-percentage uplight under industrial fluorescent systems). Maintaining equal task illumination can occur with much lower power, hence greater savings. x Cove lights and valances. Add an asymmetric reflector to cove lights to increase application efficiency and make lower watts possible. On occasion, these lights may even permit delamping. x Under and inside cabinet lighting. Check lighting levels—many under-cabinet lights produce too much illumination.
Commercial Wraparounds. Because of the wide variety of uses for wraps, the retrofitter begins with many options, some of which may be applicable to the particular situation. Some of these include: x The tendency to use wraparounds in lower-cost construction also means that the lighting levels produced may not have been “designed,” and could be unnecessarily high, allowing delamping or removal of luminaires. x Older lenses may be depreciated, and replacing them can either significantly raise light levels or allow for delamping or other energy savings in addition to technology replacement. x Removing the lens and replacing it with a formed reflecting surface, while completely changing the character of the lighting, may be a very suitable retrofit allowing for delamping up to 2:1 due to significant increase in luminaires CU. x Specular reflectors can be installed behind existing or new lenses to allow delamping as well, although the delamping may be limited to going from four- lamps to three-lamps or from three-lamps to two-lamps.
Supermarket Trough Luminaires. While technology changes are certainly appropriate retrofits, specular reflecting surfaces can be used to increase CU but may introduce an appearance that worsens visual comfort and decreases the “open for business” effect of the bare lamp in the trough. Retrofitters are encouraged to carefully assess whether a reflecting treatment might be acceptable. A better opportunity might be found in stores overlighted by current IES or industry standards.
Task Lighting. Better quality task lights employ optical controls and dimmers to manage lighting levels on the counter below, but most task lights use basic lamp and ballast technology. The result is overlighting of the counter below—an obvious energy- saving opportunity.
4-14 Lighting System Types
Table 4-3 Fluorescent Replacements
Existing Condition Equal Lumen Replacement (approx.)
F40CW/magnetic ballast (Std or EE) (40-watt T-12 RS lamps; also for F48T12FO32/8xx, elec/hybrid ballast BF=.95 40-watt slimline lamps*) FO32/7xx,elec/hybrid ballast BF=1.00
F40CW/ES, magnetic ballast (34-watt T-12 lamps) FO32/8xx, elec/hybrid ballast BF=.75 FO32/7xx, elec/hybrid ballast BF=.80
F96T12/CW (slimline), magnetic ballast (75-watt 96” lamps) FO96/8xx, electronic ballast BF=.95 FO96/7xx, electronic ballast BF=1.00 (2)FO32/8xx, elec/hybrid ballast BF=.95 (2)FO32/7xx, elec/hybrid ballast BF=1.00
F96T12/CW/ES (slimline), magnetic ballast (60-watt 96” lamps) FO96/8xx, electronic ballast BF=.80 FO96/7xx, electronic ballast BF=.85 (2)FO32/8xx, elec/hybrid ballast BF=.80 (2)FO32/7xx, elec/hybrid ballast BF=.85
F96T12/CW/HO/ES, magnetic ballast (85-watt 96” HO lamps)* (2)FO32/8xx, electronic ballast BF=1.20 FO96/HO/8xx or 7xx, electronic ballast BF=.85
F30T12CW, magnetic ballast (30-watt 36” lamps) FO25/8xx or 7xx, electronic ballast BFt.90
F30T12/CW/ES, magnetic ballast (25-watt 36” lamps) FO25/8xx or 7xx, electronic ballast BFt.80
F20T12CW, magnetic ballast (20-watt 24” lamps) FO17/8xx or 7xx, electronic ballast BFt.80
Abbreviations: 8xx means rare-earth phosphor, any color temperature, 80 + CRI; 7xx means rare-earth phosphor, any color temperature, 70 + CRI; elec/hybrid means an electronic OR hybrid ballast.
Note that high-output standard lamps (e.g. F96T12/HO/CW) do NOT have an equal lumen replacement, although in most applications, retrofits suitable of energy-saving HO lamps may be appropriate. For other existing lamps and/or replacements, make certain to equate the product of the retrofit lamp and retrofit ballast factor with the existing or designed condition.
* Lamps annotated with an asterisk may require retrofitting with low-temperature-starting ballasts when used outdoors or in cold environments.
Table 4-4 Reflectors and Delamping
Type of Luminaire Standard Efficiency Efficiency with Best CU at RCR 2.5, 50/30/20 CU with Best Efficiency Reflector Upgrade Reflectances Upgrade
Strip Light 92% 92% 65% 70%
Industrial 90% 92% 68% 74%
Wraparound 68% 74% 48% 54%
Supermarket Trough 88% 91% 68% 72%
Washdown / Vaportight 66% 72% 50% 54%
Recessed Troffer 68% 76% 55% 64%
4-15 Lighting System Types
Table 4-5 Fluorescent Task Light Retrofit Opportunities
Lamp and Ballast Type Retrofit Opportunity
F8T5, F13T5 Probably none**
F13T8, F14T8, F15T8, F30 T8 Probably none**
F14T12, F15T12 Probably none**
CF9T, CF13T Electronic ballast with low BF
F20T12 F17T8/electronic ballast with low BF, tunable or dimmable ballast, or two-level ballast.
F30T12 F25T8/electronic ballast with low BF, tunable or dimmable ballast, or two-level ballast.
F40T12 F32T8/electronic ballast with low BF, tunable or dimmable ballast, or two-level ballast.
F60T12 F40T8/electronic ballast with low BF, tunable or dimmable ballast, or two-level ballast.
F72T12 2-F25T8 OR 3-F17T8/electronic ballast with low BF, tunable or dimmable ballast, or two-level ballast.
**Electronic ballasts may be available for some of these. In addition, the appearance of some lamps can be improved through the use of rare earth phosphor lamps. Some applications may also be suitable for retrofitting with the latest T2, T3, and T4 technology. But due to low unit wattage, retrofits probably will not experience suitable payback.
In each case a major part of the savings are achieved by using the lower lighting levels created by the ballast options. For instance, an F40T12 task light uses a one-lamp T-12 rapid start or even preheat ballast, and consumes as much as 50 watts.
HID Lighting Systems
Commercial HID lighting systems are used in a number of facility types, including offices, schools, stores, airports, and shopping malls.
General Information
Troffers. HID troffers are very similar in appearance to fluorescent troffers and are made in two basic types: x prismatic lens troffers, found in a wide variety of applications, including indoor sports courts, natatoria (indoor pools), grocery stores, and other spaces with high acoustic tile ceilings. In spaces like natatoria with atmosphere considerations (e.g. water or moisture) the lens may be gasketed to help keep the luminaire clean and prevent interior materials from rusting. Heavy-duty lenses are available for gyms and game courts. x parabolic troffers, found in upscale spaces with high acoustical ceilings such as airport terminals, specialty stores, shopping malls, and atria. Most of these luminaires are for metal halide lamps and incorporate a clear lens above the parabolic louvers.
4-16 Lighting System Types
Most HID troffers are 2’x 2’ fixtures employing 250- or 400-watt lamps, usually either mercury vapor or metal halide.
Downlights and Wallwashers. Many of the architectural downlights for incandescent and halogen lamps (see prior sections) have HID versions, including open parabolic, ellipsoidal, R or PAR lamps with cones and baffles, adjustable PAR lamp, downlight- wallwashers, and various spread-lens wallwashers. These luminaires are used for both interior and exterior locations, such as overhangs and canopies, because of the low- temperature behavior of HID lamps. For indoor applications, most of these luminaires will be metal halide or mercury vapor. The poor color of HPS makes them undesirable indoors, and they will more often be found in exterior applications.
Track Lights. HID track lights are uncommon. Generally, the size of the ballast has prevented HID track lights from being developed. Other than odd and custom fixtures, only a few track fixtures exist using HID lamps. Systems most likely to be found include compact white sodium luminaires and HQI metal halide luminaires.
Indirect Lighting Systems. As ceiling height increases in office buildings and other spaces having flat reflective ceilings, uplighting becomes an appealing way of providing ambient light. HID lamps can be especially cost-effective for this application, as they can illuminate a larger area per dollar than fluorescent. While the classical drawbacks of HID remain (limited switching, color shift, etc.), these systems have been used for many years and their popularity remains high in some new designs. Metal halide systems are most common and HPS systems, while uncommon, have been developed. Most indirect systems, to make sense and minimize problems, use high- wattage lamps.
Some of the most likely lighting systems one might encounter: x suspended “puck” systems, a classic design with a reflecting system built around a vertical lamp enclosed by a cylinder resembling an oversized hockey puck to the viewer. Puck systems are usually 400–1000 watts and are used in a variety of spaces ranging from classrooms to libraries, airport terminals, and indoor tennis courts. Most puck systems are metal halide. There are some double-puck systems with metal halide and high-pressure sodium in each of the pucks, designed to overlap their light and create efficiently-generated warm-toned illumination. x suspended or panel-mounted “box” systems, usually with horizontal lamps and reflectors, up to about 400 watts. There are both round and square boxes. Some round luminaires were mounted atop cylinders on the floor, earning the nickname “water heater.”
4-17 Lighting System Types
Retrofit Opportunities
This section presents retrofit opportunities specific to HID fixture types. See also Chapter 3 for information on generic HID retrofit opportunities.
Troffers.
1. Convert 400-watt mercury vapor fixtures to 325-watt metal halide lamps and ballasts. This is one of the top retrofits because, in addition to significant energy savings, lighting levels and color will improve dramatically. 2. Investigate converting 175–250-watt luminaires to new fixtures with three T-5 twin tube fluorescent lamps and electronic ballasts. Generally, three F40T5 lamps will produce the same maintained light level as a 175-watt metal halide with savings of about 60–70 watts; three F50T5 or F55T5 lamps will produce the same maintained levels as 250-watt metal halide with savings of around 100 watts. This works because of the poor lumen maintenance of the metal halide relative to the fluorescent. An added benefit is that the fluorescent can be switched frequently. The improved color of the fluorescent and elimination of flicker will be welcome. 3. Investigate converting 400-watt metal halide luminaires to new fixtures having 6 to 8 F40T5 or F50-55T5 lamps. Keep in mind the appearance of the fluorescent luminaire in this case might not be acceptable. 4. Consider any of the other HID options, such as new lamp/ballast systems, high/low ballasts, and low wattage lamps.
Downlights and Wallwashers.
1. Interior applications in lower-ceiling spaces would generally use low-wattage lamps. Look into compact fluorescent retrofits which reduce wattage, improve color, and allow more frequent switching. For instance, replace a 100-watt mercury vapor lamp or a 70-watt metal halide with a 32- or 40-watt compact fluorescent (electronic ballast). The existing cone and trim may also need changing to match the optics of the compact fluorescent or perhaps to remove a lens. Look into conversion kits from the original manufacturer. 2. Replace higher-wattage mercury vapor lamps with metal halide, such as in spread- lens wallwashers where a 175-watt mercury vapor R or PAR lamp can be replaced with a 100-watt metal halide with new ballast and socket. This approximate wattage ratio is generally true for any wattage mercury to metal halide conversion. Remember when converting to metal halide to use self-protected (shrouded arc- tube) lamps, and to investigate state-of-the-art lamp/ballast combinations.
Track Lights. Low-wattage HID lighting systems can be expensive to retrofit and rarely will be cost-effective. Consider the following, however. x Compact white sodium luminaires, generally with electronic ballasts and in the range from 35-watt PAR lamps to 100-watt T-lamps, might be replaced with new technology metal halides. The metal halide lamp would use about 60% of the
4-18 Lighting System Types
power for the same approximate lumen output. However, related changes in light spectrum may be undesirable; so be certain to proceed cautiously with this type of retrofit. If the system is not being used for highlighting but rather for wallwashing or floodlighting, consider a fluorescent track luminaire. x Compact HQI metal halide luminaires, also generally with electronic ballast (70 watt) are already very efficient and no cost-effective retrofit opportunities exist.
Indirect Lighting Systems. Because most of these systems are higher-wattage metal halide (and/or HPS), retrofit opportunities are limited. Refer to the general retrofits for HID lamps in Chapter 3. Many of these rooms are high-ceiling spaces, and therefore, retrofits will be difficult and perhaps, too expensive. For spaces with lower ceilings, it is possible that the system is improperly designed and an all new fluorescent system may be an appropriate response, using less energy and providing better light.
There are a few low-wattage HID systems, most of them utilizing expensive luminaires that effectively prevent any type of retrofit. Note that spaces using this type of lighting may be candidates for a new lighting system, as the owning and operating problems of low-wattage HID indirect systems would probably be apparent.
Commercial Decorative Lighting
General Information
Decorative lighting fixtures are typically used in hotels, restaurants, retail stores, and other building types where their style is important as an ornament in the architectural or interior design. In addition, decorative lighting is used in office building entries and lobbies, meeting and board rooms, and other common space. Traditional and historic buildings are often completely lighted by decorative lighting fixtures.
Decorative lighting types include chandeliers, pendants, sconces, table lamps, floor lamps, and other fixtures whose enclosure is generally ornamental or designed to be part of an architectural theme. Following are some of the most commonly encountered fixture types.
Ceiling and Close-to-Ceiling Fixtures. Decorative ceiling and close-to-ceiling fixtures are used in hotels and many other commercial situations. Some of these fixtures are fluorescent, using ordinary straight tubes, U-bent tubes or Circlines. The vast majority, however, are incandescent. In all applications the usual intent is to provide lots of general light.
Chandeliers. Chandeliers were first invented to hold candles and have evolved into a wide variety of electrically-illuminated luminaires that are suspended from the ceiling.
4-19 Lighting System Types
Chandeliers differ from pendants (see below) in that chandeliers are ornate and usually traditional in style.
Traditional designs of chandeliers generally result in exposed lamps (in keeping with the exposed candles of their heritage). Many small incandescent lamps, typically clear, are consistent with the style. These lamps can utilize medium, intermediate, candelabra or mini-candelabra sockets, with smaller sockets being quite common to house the lower-wattage lamps appearing as candles. More contemporary chandeliers and the very large fixtures used in civic and historic buildings may have lamps concealed behind ornamental glass or metals. While occasionally these fixtures may actually use fluorescent or HID lamps, they typically use several ordinary incandescent lamps on medium sockets.
Pendants. Pendants are suspended luminaires that are usually smaller and less ornamental than chandeliers. Whether a luminaire is a “pendant” or “chandelier” is sometimes a matter of interpretation or taste.
Most pendants, like chandeliers, use one or more incandescent lamps. However, there are a number of modern designs of pendant luminaires using HID or compact fluorescent lamps specifically for illuminating larger spaces like offices.
Sconces. Sconces are wall-mounted luminaires that, like chandeliers, tend to be ornamental. Sconces range in style from traditional candle-like designs to extremely modern luminaires. Light distribution also varies from simple diffuse light to sophisticated, asymmetric uplights.
Sconces have been particularly appealing since the early 1980s, experiencing a renaissance of interest among architects and designers while concurrently providing an opportunity to use compact fluorescent lamps for illumination in many different space types. Although it is uncommon to find a traditional sconce with a compact fluorescent lamp, most new sconce designs offer incandescent or compact fluorescent options.
Table Lamps. There are many designs for table lamps. Some might be called “task lights;” they are modern in style and designed to be moved into position near the task. Task lights are commonly used as supplemental lighting in offices, usually as a stop- gap measure because the built-in lighting is inadequate at that particular location. The relatively high cost of an attractive task light limits use of the best products to executives, but modest luminaires like the classic “architect” lamp are used in many situations.
More traditional table lamps have been limited to residences, hotels, and executive suites, mostly to play to the residential aesthetic. However, the plain table lamp with
4-20 Lighting System Types an appropriate light source (fluorescent) and properly shaped shade may be an excellent task light for many situations, including computer-intensive offices.
Floor Lamps and Torchiers. While the traditional floor lamp is as varied the as the table lamp, “torchier” is the name given to contemporary floor luminaires. Many torchiers have an uplight distribution, usually equipped with a relatively high-wattage halogen lamp. A few designs have been recently introduced using compact fluorescent lamps.
Marquee Lights. Marquee or string lights are used for a variety of interior and exterior lighting accents at theaters, hotels, restaurants, casinos, and other entertainment facilities. Typical marquee lamps are medium, intermediate or candelabra based lamps between 10 and 60 watts, usually in a G (globe) or S (sign) bulb. Often marquee lamps are controlled by dimmers or electromechanical switches.
Retrofit Opportunities
Decorative luminaires present a challenge to the retrofitter that he or she does not normally encounter. The primary objective requires an equal balance of aesthetics and energy efficiency. To achieve efficiency without retaining (or improving upon) the appearance and quality of the space will usually be unacceptable.
If Dimming Is Important. Many chandeliers and sconces, especially in hotel meeting rooms and conference facilities, operate from an incandescent dimming system and often for good reason. If dimming is present and used, consider one of the following possibilities. x Reduce lamp wattage. Many installations rely upon dimming and never operate lamps at 100% power. By changing the use of the dimming, socket watts can be reduced considerably. For instance, a 100-watt lamp typically operated at 75 watts produces about the same light as a 60-watt incandescent lamp at full brightness. While relamping costs will increase, energy consumption will decrease. Keeping the right lamp in the socket is, of course, the biggest problem: Try using stickers noting the correct wattage. x Use halogen lamps of lower wattage. For installations run at full light periodically, try lower-wattage halogen lamps, such as a 75–90-watt replacement for a 100-watt incandescent lamp. Note that if “long-life” lamps have been used in the past, a lower-wattage halogen lamp can be used because long-life incandescents are less efficient than standard incandescent. x Consider converting small incandescent lamps to low-voltage halogen. A tricky job, but a 5-watt halogen 12-volt lamp can generate as much light as a 10-watt incandescent.
4-21 Lighting System Types x Reduce the amount of light generated from the dimmable source. Especially if other sources of light are available and/or the light levels are high, this will permit the direct use of incandescent lamps of lower wattage.
It may also be possible to retrofit the lighting with a dimmable compact fluorescent. Dimming ballasts for compact fluorescent lights are available, but most require a dimming device and control signal that prevents use of the existing incandescent wiring. Recent developments in fluorescent dimming, however, have included a few dimming ballasts that can respond to the signals of an ordinary incandescent dimmer. The compatibility of the ballast and dimmer will be critical in considering this type of retrofit. Changing the dimmer may not be easy: it may involve rewiring and may not even be possible with the dimming system.
If Dimming Is Not Important.
1. Convert fluorescent luminaires to T-8 lamps and electronic ballasts. This retrofit is straightforward and almost always desirable. Note that because many of the applications of decorative fluorescent fixtures are overlit, consider using low ballast factor electronic ballasts.
2. Reduce socket watts. There are many ways to do this. x Simply settle for less light. Reducing lamp wattage is easy and cheap. However, this method is unlikely to persist, since the user’s could revert to the old set-up. x Make a lamp type change. For marquees and other applications using exposed G lamps, retrofit products using several low-wattage lamps inside a G lamp bulb will create an acceptable new effect. Typical replacement uses a 7-watt screw-in device (with 7 small 1-watt lamps) to replace a 25–40-watt regular incandescent G-25 or G-40 lamp. The lighting level will diminish but the sparkle will actually increase.
3. Screw in a compact fluorescent. The evolution of compact fluorescent screw-in lamps permits many incandescent lamps to be directly replaced, especially in luminaires that use a shade or shield. Keeping in mind the (approximate) 4:1 relationship between incandescent and fluorescent watts, the higher-wattage compact fluorescent lamps will prove to be more desirable to equal the light output of a 100+ watt incandescent lamp.
Table and floor lamps may require changing either the harp, the shade, or often both. Consider using screw-in adapters where the ballast and socket are semi- permanently installed to prevent theft and snap-back. Lamps with three-way sockets can be equipped with one of several types of three-way CFL products on the market.
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Other decorative luminaires often allow direct replacement of incandescent lamps with self-ballasted screw-in compact fluorescents. To prevent snap-back, semi- permanent ballast/socket kits are recommended, as are hard-wired conversions (see below). However, the low cost of ordinary medium-based CFL’s may be sufficiently attractive to make the snap-back and theft risks worth taking.
4. Make a hard-wired conversion to compact fluorescent. This is the preferable way to make a retrofit that persists and has low theft value. Most conversions are not easy and there is often no room for the ballasts. However, the recent introduction of compact electronic ballast packages makes these conversions even easier. Inline ballasts may also be used for permanent conversions of table and floor lamps, keeping in mind that the preferred lamps may require four wires and therefore, rewiring of the luminaire.
Special Considerations for Wall Sconces. In 1992 the Americans with Disabilities Act (ADA) became Federal law. Among its many requirements is the prohibition of wall sconces that project more than 4” from the wall when mounted 80” or less above finished floor in a hallway or path of egress. Most incandescent decorative sconces fail to meet the law. Rather than retrofit, many building owners choose to replace non- complying incandescent sconces with complying fluorescent sconces. New products are available in every design style and cost.
Commercial Utility Lighting
General Information
In addition to the mainstream lighting systems of commercial facilities, there are a wide variety of special-purpose and utility lights using many different light sources. Often, there are just a few of these compared to the quantity of regular lighting systems. Retrofitting them is generally advisable, both to save energy and to permit more consistent maintenance.
Strip Lights. Fluorescent strips are used in a variety of applications, from valence and cove lights to closet lights, task lights, and many other utility applications.
Case Lights. Used inside of cases for everything from food to jewelry, case lights consume a surprising amount of energy. Incandescent case lights include showcase- lamp and low voltage styles. Fluorescent case lights use a variety of straight fluorescent types, ranging from very short T-5 preheat lamps to 8’ slimline and HO case lights for food and other large displays.
In assessing case lights, it is important to note that around food, protective covering is required. Sleeves that slip over lamps or lamps with integral plastic sleeve protection
4-23 Lighting System Types are commonly used. Bare and unprotected fluorescent and incandescent lamps are generally not permitted around food, the only exception being the thick hard glass- protected PAR lamps. Lamps inside of refrigerated cases may also require sleeves to maintain temperature and therefore, light output.
Vanity Lights. Lights specifically designed for vanity lighting are used for these and other applications. Generally, a vanity light is designed to be mounted over or beside a mirror. Incandescent vanity lights are used in homes, hotels, and many other commercial and industrial applications; fluorescent vanity lights are less common and are usually found in modest facilities.
The appearance of the vanity light may be important. In other cases, durability may outweigh other considerations.
Step Lights. Interior and exterior step lights are used for stairs, walkways, and similar situations where a low wall-mounted light is needed. Incandescent, fluorescent, and HID versions can be found. In particular, HID versions tend to be for exterior applications but may be used indoors in commercial space.
Step lights tend to be the least efficient way to illuminate a path; so in assessing step light installations it is important to confirm that step lights are the only good solution. Sometimes the opportunity exists to remove and replace them with more efficient horizontal surface illumination such as downlighting.
Retrofit Opportunities
The wide variety of utility lights makes specific retrofits hard to recommend. The following general considerations can be followed, and the retrofit designer should evaluate each case independently to assure the best choice.
1. Always consider replacing incandescent fixtures with new fluorescent luminaires designed to do the same job. This is especially true for vanity lights, display case lights, and other luminaires where a technology retrofit would not be possible or might entail considerable luminaire reconstruction. 2. For step lights and other sources that conceal the lamp, investigate incandescent-to- fluorescent or even HID-to-fluorescent conversions. Screw-in CFLs are a reasonable idea here as the lamps are not easily accessed except by trained personnel. In replacing a low-wattage HID with fluorescent, it is possible to remove the HID ballast and replace it with a compact fluorescent ballast; of the same input voltage. Incandescent luminaires probably do not have the space for a ballast so a screw-in CFL may be preferred. 3. Of course, be concerned if the luminaire is being dimmed. (Dimming considerations and options are discussed under decorative lighting.)
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4. For luminaires already using fluorescent lighting, it is probably best to apply recent technology, such as T-8 lamps. Note that in refrigerated cases, low-temperature ballasts and tube-warming jackets will be needed. In many other situations, use of low-ballast factor electronic ballasts will result in acceptable lighting levels but save the maximum amount of energy.
Exit Signs and Other Self-Illuminated Signs
General Information
Self-illuminated exit signs are required by fire code in commercial buildings and in multiple-residential buildings like condominiums, hotels, and motels. Some self- illuminated directional and advertising signs are very similar in construction.
Because exit signs are regulated by fire codes and their appearance and brightness fall under the jurisdiction of the fire marshal, take particular care when assessing exit signs for possible retrofit. Following are some of the key options and considerations: x Face color is important but surprisingly inconsistent. Some municipalities require red letters; others require green. The surrounding field about the letters seems less important; so one may find red letters with black, white, or other background acceptable to the same fire marshal. x Many exit lights have a lens in the bottom to provide downlight. The downlight is often part of an overall emergency path lighting scheme and should be regarded as critical unless other more specific emergency lighting is provided for this purpose. x Whether an exit sign is single or two-sided may dramatically affect the retrofit approach x Many exits incorporate a battery backup, often with separate low-voltage incandescent lamps in the event of power failure. x The vast majority of exit luminaires are incandescent, usually using two low- wattage, long-life incandescent lamps for normal power operation. Lamp life is rated especially long; so assumptions about relamping when evaluating economics of retrofitting should be guarded. x The battery backup units employed in many exits may no longer work. Be certain to check while assessing the installation. Failure will probably be due to battery failure. If the battery system fails to work, this may encourage an all-new exit sign rather than retrofitting and replacing the battery.
Retrofit Opportunities
Exit signs in which the downlight must be maintained have two options:
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1. Replace the incandescent lamps with compact fluorescent. Two 5- or 7-watt twin tube lamps are quite suitable for replacing the two incandescent lamps usually found with a net savings of around 15–18 watts per lamp. These conversions, which are hardwired, are inexpensive and work fairly well. The primary disadvantage is that lamp life of the compact fluorescent will probably be shorter than the incandescent it replaces. 2. Replace the luminaire with a new unit employing LED faces and LED downlight. First costs will be higher, but energy savings increase as well. One of the advantages of this retrofit is that LED life is extremely long—much longer than long life incandescent or fluorescent.
Exit signs not employing (or not needing) downlight enjoy other options:
1. Replace incandescent lamps with LED retrofits. There are a number of different types of kits designed for this purpose. Be certain to use the right color. 2. Replace incandescent lamps with compact fluorescents. This retrofit saves energy but has drawbacks, including short lamp life. 3. Replace incandescent lamps with incandescent rope light or other types of specialized adapters. (These work by placing incandescent lamps in optically more efficient locations and by distributing the light source.) 4. Replace exit signs with radioluminescent or other types of signs that generate light without electricity. While these signs have the lowest light levels (and may not meet fire marshal requirements), they also consume no energy.
It is especially important to obtain the input of the local fire marshal with respect to any exit sign retrofit. Most retrofits change the amount of light and the character of the lighting and sign sufficiently that the retrofit—even if it is tested to comply with UL safety requirements and listed—may not be acceptable to the authorities.
Track Lighting
General Information
Track lighting was invented in the late 1960s as a means of bringing some of the versatility and drama of theatrical lighting to architectural projects. It rapidly became the standard means for lighting retail stores, museums, galleries, and similar facilities. But it is also a popular means of solving lighting problems in a wide range of projects ranging from churches to restaurants.
Tracks made by different manufacturers are generally NOT interchangeable. A track fixture or “head” made for one brand of track will not fit another brand. Track itself is one of several configurations: x single 20A circuit (common lowcost track)
4-26 Lighting System Types x two 20A circuit (most commercial and museum heavy-duty track) x three or four 20A circuit (rare; heavy-duty grade) x one, two, or more circuits greater than 20A (also rare, heavy-duty grade)
Most track is the lighter commercial grade. Heavy-duty tracks, which can be identified by the heavier-gauge aluminum track and beefier head connectors, are generally used in museums and convention facilities where change is common and larger fixtures are used. Commercial grade track is used in stores and other situations where ordinary heads are used and change is less frequent.
Almost all tracks are fed at 120 volts; but occasionally, tracks are energized at 12 volts. Standard track operated at 12 volts with specially wired heads has been known to have connection problems and fire potential; track systems designed specifically for low- voltage do not have this type of problem as the connections are better designed for the high currents needed for low-voltage lamp operation.
A monopoint is a track or track-like head mounted to a canopy cover or junction box. Track makers produce a canopy with a short piece of track allowing a single head to be installed. Sometimes the canopy has an integral transformer allowing a low-voltage head to be mounted to it.
Standard track fixtures or “heads” include x R or PAR lamp heads, by far the most common. They are used to accentuate artworks and displays. x low-voltage PAR-36 and MR-16 lamp heads, used in a manner similar to the above but allowing the greater focus and precision of low voltage lighting. There are a few products with built-in reflector systems that use the tiny bi-pin halogen lamps instead but perform in a similar manner. x heads that turn “A” lamps and “SB” lamps into display spots or floods. Far less common, these fixtures have built-in reflectors for the standard lamp. x Wallwasher heads using A lamps, 100–250-watt halogen lamps, or fluorescent lamps. x special display heads using high-wattage halogen PAR lamps x special display heads using metal halide PAR, metal halide HQI, or white sodium lamps
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Retrofit Opportunities
Before proceeding, it is a good idea to make sure the track system connections are tight and functioning. Any sign of arcing or burning on the track should be investigated and the problem fixed.
Retail Display Lighting. Most retail display lighting requires drama and punch. This cannot be provided by fluorescent retrofits, particularly medium based screw-ins. Use halogen or halogen infrared-reflecting lamps to reduce lamp watts but maintain essentially similar performance and appearance.
The best opportunity to retrofit retail display track is when fixtures are being used as wallwashers. Electronically ballasted fluorescent wallwashers using twintube lamps actually work better than incandescent or halogen wallwashers and at greatly reduced power. Most track manufacturers now make one or more standard products that can be simply “plugged in.”
Grocery Stores, Car Dealerships, and other Larger Displays. New metal halide and white sodium track heads can be used to replace incandescent and halogen heads when illuminating larger areas such as produce gondolas, cars, and sporting goods.
Restaurants, Hotels, Houses of Worship, Theme Parks, and other Designed Spaces. Generally, track used in these facilities is being used to create a specific appearance. It is often dimmed. Retrofits should be limited to halogen or halogen infrared-reflecting lamps with special attention to creating a similar effect.
Convention Facilities. Convention halls and many hotel ballrooms employ track to illuminate speakers, head tables, temporary displays, and other events. This is specialized lighting that probably should not be part of a retrofit program.
Other Casual Uses of Track Lighting. There are many places where track has been used for convenience. Using careful judgment, the retrofitter may find some incandescent track heads could use a self-ballasted CFL that would provide satisfactory performance.
Industrial
Industrial Fluorescent
General Information
Industrial luminaires are generally open strips with symmetric reflectors as part of the body of the luminaire. Economy industrials are often called “shop lights” and are sold
4-28 Lighting System Types at hardware stores as well as through normal electrical distributors. Better-quality industrial fluorescent luminaires have larger reflectors, in many cases with slot openings in the top to permit a small percentage of uplight into the space. The most expensive industrials may have separate parabolically-shaped lamp compartments.
In addition to the basic luminaire, industrial luminaires may be equipped with a wide variety of options, many to protect the lamp from breaking and workers from broken glass as a result. The most common include x protective wire cage guards x egg-crate louver, usually white flat bladed x prismatic lens
The better-quality industrial luminaires may be finished in baked enamel paint or porcelain, particularly if the designer was concerned about longevity and resistance to corrosion. Or the luminaire body might be aluminum rather than steel, again to minimize the negative effects of corrosion. Surface reflectivity can be assumed to depreciate and offers reasonable retrofit opportunity. However, the retrofitter should assess the atmosphere in the application to determine the requirements of the luminaire’s surface finish. For instance, white powder coat replacement reflectors may be more suitable than specular reflecting materials due to the application’s environment. In addition, lamp sockets are often different, using turret-type and spring-loaded sockets to better hold lamps and maintain contact pressure despite frequent vibration.
If the lighting levels of an otherwise older and/or poorly maintained lighting system are found to be adequate, then considerable opportunities to save energy include optical improvements such as replacement of (or repainting) reflecting surfaces; replacement or removal of lenses; replacement, repainting, or removal of louvers; and lowering lighting systems to improve the CU by reducing the room cavity ratio (RCR). Of course, these savings are added onto technology changes to modern lamp/ballast systems.
But many older lighting systems no longer produce acceptable illumination due to inadequate maintenance. The retrofitter should determine whether this is the case before proceeding. Renewing the lighting system with a technology upgrade and new, clean reflecting and refracting materials might be the best service for the customer.
Retrofit Opportunities
Industrial lighting applications may offer redesign opportunities that save energy with a minimum amount of change-out. For instance, changing from general illumination to
4-29 Lighting System Types task-and-ambient solutions, combined with technology upgrades, may save the most energy and minimize cost by adding only task lighting where needed.
Most industrial fluorescent luminaires can be directly retrofitted with T-8 lamps and electronic ballasts. Considering the many options—standard T-8, T-8 lamps with low or high light level ballasts, high output T-8 systems—it should be possible to retrofit all but VHO fluorescent systems directly.
In cases where slimline, HO, and VHO fluorescent are being used, it is important to ascertain the design temperatures before considering a retrofit. HO and VHO systems tend to operate well at low starting and ambient temperatures. If the application is strictly for general lighting, however, sometimes a retrofit employing mulitple F32T8 lamps can be used. For example, a single lamp luminaire using an F96T12/HO/CW/ES lamp (8000 lumens) might be retrofitted with two F32T8 lamps and a two-lamp high-light-level ballast (7400 lumens). Or, a luminaire employing two F96T12/HO/CW lamps (17,600 lumens) might be retrofitted with eight F32T8 lamps with low-light-level electronic ballasts (17556 lumens).
Watertight Fluorescent
General Information
Sealed and gasketed or “watertight” fluorescent luminaires are used in applications where either the atmosphere surrounding the luminaire is expected to be constantly wet, or in those situations where extreme dirt build-up is intended to be removed by periodic high-pressure washing using water with or without detergent.
Although there are many different styles, the most common is a rectangular fixture, typicallly 4 or 8 feet long and 8” to 12” wide. Most watertight fluorescent fixtures employ a plastic or fiberglass chassis and use few or no exposed metal parts to further withstand corrosion.
The lens is usually a single piece of injection-molded plastic that might be clear, diffuse, or employ a prismatic pattern. In most applications, the photometric distribution of the luminaire is not demanding. Observe closely how the existing ballast is mounted— ballast case heat dissipation is a problem with non-metallic fixture housings. Starting and operating temperatures may also be a concern, as often these fixtures are used in unheated spaces.
Retrofit Opportunites
The primary opportunity is converting the fluorescent lamps to T-8 type with electronic ballasts. Make certain the starting temperature of the new ballast is correct. Secondary
4-30 Lighting System Types opportunities might include the addition of a specular or white reflector to increase the downward light component. This will change the luminaire’s performance; so carefully evaluate the photometric difference.
Also investigate the lens being used. Replacement of an aged lens or substitution of a clear or prismatic lens in place of a diffuser can increase fixture efficiency enough to warrant use of a lower ballast factor or perhaps even a lesser output lighting system.
HID High Bay Area and Aisle
General Information
So-called “high bay” fixtures are designed specifically for use in spaces with a need to maintain a clear height of roughly 25 feet or more. Applications of high bay fixtures are not limited to industrial spaces, for they are used in all types of high space, notably gymnasia and similar spaces, where utilitarian-appearing luminaires are acceptable. High bay fixtures generally are between 250 and 1000 watts. Different distributions of candlepower, including width of beamspread and special beam shapes as for aisles between equipment or storage racks are some of the major options. Aluminum, glass prism, and acrylic prism reflectors are used, with minor advantages to each. Uplight provided by a gap between the socket and reflector or from the glass or acrylic reflector helps make this lighting more comfortable.
High bay systems may be installed in a number of ways. Some high bay lighting systems are installed on a wireway system not unlike track lighting, permitting relatively easy fixture removal, relocation, and replacement. In other installations, hook hangers and cord-and-plug installation permit rapid removal and replacment of a faulty unit. And of course, conventional hard-wiring installations are used in many buildings. The wiring method may affect retrofit situations more than most other lighting types, if for no other reason than the height of the luminaire.
Retrofit Opportunities
High bay applications suggest the following primary considerations:
1. Convert mercury vapor luminaires to metal halide or HPS. The cost of converting may suggest a new luminaire instead of any kind of rewiring. 2. Examine the various lamp and ballast options in the section on HID lamps, such as the metal halide linear reactor and hybrid systems, lower-wattage lamps and two- level systems (both MH and HPS). Also consider removing metal halide lenses and using self-protecting lamps, especially where the lens is visibly dirty. 3. Examine the possibility of changing to a task-and-ambient lighting design in which the general lighting levels are made lower and supplemental task lighting, mostly 4-31 Lighting System Types
fluorescent, is used only where needed. It may be possible to reduce the general lighting system’s power considerably while achieving a net improvement in task lighting. 4. Consider low-wattage metal halide lamps to retrofit existing metal halide fixtures. For instance, replace a 400-watt lamp with a 360-watt lamp without any noticable change in light levels or performance. (Note lamp operating position limitations— usually not a problem in high bay lighting as lamps are usually vertical, base up).
Relatively new information on visibility and high-pressure sodium sources may affect the lamp selection for high bay lighting. While there are no problems with HPS lighting for most industrial situations, metal halide is clearly advantageous in rendering small targets such as industrial assembly or fine machining. Also keep in mind the flicker of both metal halide and HPS lamps, and make certain lamps are rotated in phases to minimize stroboscopy. In some cases, it may be desirable to replace existing HPS lamps with metal halide, for which there are a few specific metal halide lamps designed to operate on HPS ballasts.
HID Low Bay Area and Aisle
General Information
Low bay fixtures differ from high bay in that they are optimized for lower mounting heights and wider distribution. Most low bay fixtures are enclosed, using the lens to distribute light evenly as well as to protect the lamp from damage. The maximum wattage of low bay industrial fixtures is usually 400 watts. Typical low-bay luminaires are 70–175 watts.
Low bay luminaires also differ from high bay in that a refractor (lens) is ususally employed, both to protect the lamp and to gain higher angle distribution. Unlike the high bay, in which luminaires are generally mounted far above the work and access area, low bay luminaires are often mounted just slightly above the work area and need far wider distribution. It is not uncommon for a low bay fixture to have a spacing-to- mounting-height ratio >1.5 (most high bay fixtures are less than 1.5).
Retrofit Opportunities
One option for replacing low bay HID systems is fluorescent. Conventional industrial fluorescent lighting and low bay HID luminaires are similar in efficiency and CU. A 250-watt metal halide lamp will produce about 17,000 mean lumens, about the same as two F96T12/HO lamps. But with an electronic ballast the fluorescent luminaire uses only 209 watts, compared to 295 for the HID. Side benefits of the fluorescent include rapid starting, better color and elimination of flicker, and lower LLD. For low bay
4-32 Lighting System Types spaces requiring good color, it may be hard to beat electronically ballasted fluorescent. The fluorescent lamps will last longer, too.
For spaces not suited for long fluorescent luminaires, consider low bay luminaires with multiple compact fluorescent lamps. Products resembling HID luminaires but having 6 or 8 26-to 32-watt CFLs are an option to replace 250–400-watt HID luminaires. With electronic ballasts, this system offers flicker-free performance, good color, and energy efficiency. Optical properties suffer; so high bay applications of this concept may not work as well.
It will be difficult to make a simple retrofit of a low bay luminaire. Among the limited number of choices, consider direct lamp replacements like the 225-watt and 360-watt metal halide (energy saving replacements for the 250 and 400); the 325-watt metal halide (energy-saving replacement for the 400-watt mercury vapor); and the 150-, 215-, 360-, and 880-watt high pressure sodium (direct replacement for the 175-, 250-, 400- and 1000-watt mercury vapor lamps, respectively). In areas where fine or detailed work is being performed, also consider the 250- and 400-watt metal halide replacements for 250- and 400-watt HPS. While no energy is saved, visual performance will improve.
HID Vaportight
General Information
Vaportight fixtures, sometimes called “jelly jars,” are a utility industrial luminaire used indoors and out. There are many related fixtures of similar appearance, such as special fixtures for petrochemical plants, explosion-proof spaces, and aircraft obstruction lights.
Retrofit Opportunities
Most vaportight fixtures have only basic optical systems, if any at all. Investigate any retrofit resulting in equal maintained lumens, being careful to choose systems that will operate at the temperature extremes expected of the environment. For many normal temperature range applications, however, look into compact fluorescent replacements of low-wattage HID luminaires as a primary opportunity. For higher-wattage lamps, see the section on lamp technology and retrofits.
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Special Purposes/Environments
General Information
Industrial luminaires exist for many special applications. Among the most basic types are wet “wash-down” location luminaires; cold temperature luminaires; vaportight and hazardous environment luminaires; clean room luminaires; and industrial task lights.
Retrofit Opportunities
In general, the more specialized the environment, the more the retrofitter should be encouraged to carefully upgrade the basic technology with equal lumens, keeping in mind potential pitfalls such as very high or very low starting or operating temperatures. A critical concern with specialized applications is the resulting light levels and lighting distribution, ensuring that retrofitting look beyond simple lamp lumen ratings.
Outdoor
Street and Road Lights
General Information
There are many types of street and roadway luminaires. The two most common are the “cobrahead,” which uses a lens to guide light from an HID lamp to the road and sidewalk, and the “shoebox,” which uses a reflector to do the job. “High mast” lights are used on tall poles at major freeway intersections, large parking lots, and large industrial outdoor areas.
What all of these lighting systems have in common is significantly more engineering than most other lighting systems. The precise optics, including lamp position, are used to calculate lighting levels to determine compliance with relatively rigid guidelines. Changes to the optical system are to be avoided unless carried out with precision and care.
Retrofit Opportunities
A large percentage of outdoor street lighting is still using mercury vapor lamps. Special versions of high-pressure sodium lamps are available as socket-for socket replacements, making it very easy to retrofit without changing the ballast. High-pressure sodium lamps use about 50–60% of the original mercury vapor watts while producing equivalent lighting levels.
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Other than that, there are no common options for retrofitting most of the existing HPS, metal halide, and LPS street lights that employ high performance luminaires like the cobrahead or shoebox. Decorative street lights, on the other hand, present an opportunity. Ordinary “acorn” and “lollipop” area lights can be replaced with new heads that prevent upward and side radiation, thereby permitting use of a lower- wattage source.
Floodlights and Billboard Lights
General Information
Floodlights are used to illuminate outdoor areas ranging from parking lots to athletic fields. They are also used for other outdoor applications such as lighting a building or monument. In general, they are metal luminaires with a glass face that are adjustable to aim at the area to be illuminated. Light sources may include incandescent, halogen, fluorescent, compact fluorescent, or HID. Most floodlights are general purpose types with wide angle distribution, but specific types are also made with narrow and asymmetric light patterns.
One common variation is the billboard light. These are luminaires designed for uplighting outdoor signs and billboards, and are also used for some types of building and wall lighting. Billboard lights are generally either HID or HO fluorescent.
Retrofit Opportunities
One of the most common floodlights in use is a compact unit using a double-ended, 300- to 500-watt tungsten halogen lamp. These luminaires are handy and inexpensive, but use a very low efficacy light source. If used in places where frequent switching and the need for instant light is common, they remain an acceptable choice; but retrofitting with HIR lamps is recommended to save energy. The 300-watt lamp is replaced by a 225-watt HIR and the 500-watt by a 350-watt HIR, resulting in similar radiated light. In other cases, compact floodlights with T-5 twin tube lamps up to 55 watts might be used in their place if a reduction in light level is acceptable and ambient temperatures are not too low. To maintain similar light levels in long operating period applications, use metal halide or HPS luminaires of 100–150 watts.
In most commercial applications, HID lamps are already being used. Most energy- saving opportunities are the standard considerations for HID retrofits, such as replacing mercury vapor lamps or using high-wattage CFLs. But in addition, many general purpose, wide throw floodlights are being used where a luminaire with specific beam distribution might work better. Consider lower-wattage luminaires with
4-35 Lighting System Types a more precise beam pattern. Savings of up to 50% or more may be possible if existing lighting systems waste or spill light into the sky or onto adjacent properties.
In a few cases, fluorescent floodlights and sign lights might be retrofitted with electronic ballasts. Keep in mind the application’s required starting temperature and select the ballast accordingly.
Wallpacks
General Information
Wallpacks are typically low-cost, rugged, general purpose luminaires designed to be mounted to a building’s exterior wall and provide area illumination around the building. Most common wallpacks are low-wattage HID or high-wattage compact fluorescent. There are also a number of low-cost incandescent luminaires used for a similar purpose, often called “wall brackets.”
Retrofit Opportunities
Keeping in mind starting and operating temperatures and other considerations, evaluate retrofitting most incandescent wall brackets with low-wattage HPS or CFL lamps. Or, retrofit the luminaire with the lowest possible wattage tungsten halogen lamp and install a motion sensor to the luminaire or junction box.
Most HID wall packs are specifically designed for the lamp and chosen to fulfill a security or other need. Other than the general retrofits for any HID lamp, it may be worthwhile evaluating the lighting need and the luminaire’s performance. Many HID wallpacks, especially HPS, produce an unnecessarily high amount of light, and a lower-wattage HID or even compact fluorescent luminaire may be acceptable.
Bollards
General Information
Bollards are lighting fixtures, typically about waist-high, used to illuminate walkways in parks and near buildings. Decorative bollards may use incandescent or low-wattage HID lamps. Almost all commercial bollards employ low-wattage HID lamps, including mercury vapor, metal halide, and HPS, seldom exceeding 100 watts.
4-36 Lighting System Types
Retrofit Opportunities
As with other outdoor lights, incandescent bollards might be retrofit with compact fluorescents provided that the lamp and ballast are appropriate for the temperatures experienced in the application. Since most bollards have room to install a ballast, outdoor-rated hardwired ballasts and amalgam compact fluorescent lamps might be used to replace incandescent lamps to 200 watts and HID lamps to 70 watts, depending on bollard construction and optics. Of course, mercury vapor lamps might also be replaced with HPS, metal halide or compact fluorescent. Higher-wattage HID bollards may not be as suitable for retrofit.
Parking Garage Fixtures
General Information
Parking garages are illuminated either by HID luminaires designed for this use, or by generic fluorescent lighting such as strip lights. It is uncommon to find a parking garage with incandescent lighting or HID luminaires that are not designed for this use. HID garage luminaires are becoming increasingly sophisticated, with special lenses and reflectors designed for widely-thrown downlight and some uplight for better visual comfort. Traditional HID garage luminaires use refractor lenses or faceted reflectors resembling shoebox street lights.
Retrofit Opportunities
If traditional fluorescent lighting is used, keeping in mind the temperature range of the application, consider electronic ballasts possibly with T-8 lamps.
Retrofitting HID systems will require careful analysis and planning. The primary concern is the performance of the luminaire’s optical system—different lamp shapes or source centers might cause the lighting system to work differently. Keeping this in mind, investigate the standard HID retrofit opportunities, especially for mercury vapor garage lighting systems.
Step Lights
General Information
Step lights and other low-level lights are typically mounted in walls of buildings around knee height, with the intended purpose of illuminating the path. Some step
4-37 Lighting System Types lights use lenses or reflector lamps to produce specific beam patterns, while others utilize louvers or lenses to produce general lighting.
Retrofit Opportunities
Most older step lights are incandescent; so a retrofit will often utilize a CFL. Indoor step lights are generally in good condition and any suitable CFL adapter might be used. Exterior step lights often have suffered from weathering and may need a cleaning and/or replacement of critical parts before retrofitting.
HID step and low-level lights might be retrofit. Investigate the standard HID retrofit opportunities, especially for mercury vapor luminaires. Keep in mind that a higher wattage compact fluorescent (26–42) might be used in luminaires that already have ballast compartments.
Landscape Lights
General Information
There are many types of landscape lights used in a wide variety of residential, commercial, and other applications. Some of the most common are: x the “bullet” usually used as an uplight for trees x the “pagoda” and “coolie hat” walklights x the “tulip” and other styles of planter box lights x in-ground uplights for trees and statuary
Retrofit Opportunities
Most landscape lighting is incandescent. Modest retrofits such as using 60-watt HIR PAR-38 lamps in place of 150-watt PAR-38 will be easy, inexpensive, and cost-effective. Similarly, using CFLs of appropriate starting temperature in walklights may also work. New landscape floodlights using compact fluorescent lamps might be used to replace older incandescent luminaires.
Occasionally one will find HID or full-sized fluorescent lighting being used in landscape applications. In addition to the standard considerations for these lamps, it may help to assess the need for the HID source, or perhaps, to check to see if the luminaire is performing as planned. It is common in outdoor lighting for luminaires to suffer from weather, and landscape lighting also suffers from irrigation and careless landscape maintenance. For example, be sure to check if an in-ground uplight’s lens
4-38 Lighting System Types has not been ruined by mineral etching, which would turn a spotlight into a wide flood lamp.
4-39
5 SUMMARY OF RETROFIT OPPORTUNITIES
This chapter presents a summary of lighting retrofit opportunities that should be considered. The chapter is intended as a quick reference; only a brief description of the recommended retrofits is presented. More detail is provided in Chapters 3 and 4. In addition Chapter 2 presents details on methods that can be used to evaluate the opportunities.
Commercial
5-1 Summary of Retrofit Opportunities
5-2 Summary of Retrofit Opportunities
5-3 Summary of Retrofit Opportunities
5-4 Summary of Retrofit Opportunities
5-5 Summary of Retrofit Opportunities
Industrial
5-6 Summary of Retrofit Opportunities
5-7 Summary of Retrofit Opportunities
5-8 Summary of Retrofit Opportunities
Outdoor
5-9
A GLOSSARY OF TERMS
absolute contrast The difference in reflectance between a visual target and its immediate background, without regard to color of target or background. absorption The dissipation of incident flux within a surface or medium. accent lighting (highlighting) Light that emphasizes a particular object or objects, or that draws attention to a specific area within the field of view. accommodation The process by which the eye changes its focus from one distance to another. adaptation The process by which the eye becomes accustomed to varying quantities of light or to light of a different color than it was exposed to during an immediately preceding period. Results in a change in the eye's sensitivity to light. adaptation compensation A lighting control strategy aimed at matching illuminance to the adaptation level of the eyes of persons entering the space. ambiance Mood or feeling in a space, as evoked by that room's lighting system. ambient lighting Electric and/or natural lighting throughout a space that produces uniform general illumination. angle of incidence The angle between the normal to a surface and the path of light striking the surface.
ANSI The American National Standards Institute.
ANSI conditions The conditions under which most lamps and ballasts are tested for light output, lamp life, etc. Generally means open (a non-enclosed luminaire) conditions, in unmoving air, at 25°C (77°F). application thermal factor (ATF) A measurement used in lighting calculations to account for the effects of a lamp's bulb wall temperature on fluorescent lamp lumen output. ATF varies depending on luminaire, lamp, and ballast type. arc discharge A transfer of electricity across two electrodes (anode and cathode), characterized by high electrode current densities and a low voltage drop at the electrode. architecturally neutral luminaire A luminaire whose design and/or mounting characteristics allow it to be easily integrated into architectural and interior design schemes. architecturally positive luminaire A luminaire designed to attract attention to a space and evoke an emotional response; an ornamental or decorative luminaire.
A-1 Glossary of Terms
asymmetric distribution A light distribution pattern in which lumen output is directed more strongly toward one side than another. baffle A lamp shielding device that absorbs unwanted light or shields a light source from direct view. ballast A magnetic or electronic device used to control the starting and operation of discharge lamps. ballast efficacy factor (BEF) A measure of energy efficiency used to establish minimum ballast performance parameters for component efficiency standards. The figure is determined by dividing the ballast factor by input power. Current federal and state BEFs are in effect for F40T12 and F96T12 ballasts. ballast factor (BF) The ratio of lamp lumen output on a particular ballast as compared to that lamp's (lamps') rated lumen output on a reference ballast under ANSI test conditions (free, unmoving air at 25°C). beam spread A measure used for directional type lamps. The angle between two directions in any plane in which light intensity (in candlepower) is equal to a stated percentage of the maximum beam intensity. Generally, the percentage is 10% for flood lamps and 50% for photographic lamps. black body radiator A temperature radiator of uniform temperature whose radiation in all parts of the electromagnetic spectrum is the maximum obtainable from any temperature radiator at the same temperature. A black body radiator is used to determine the color characteristics of light sources. brightness The subjective intensity, as determined by an individual's perceptive processes, of the sensation that results from viewing a light source or a surface or space which directs light into the eyes. Is often used incorrectly in place of the terms "illuminance" and "luminance." bulb The glass outer envelope component of a lamp. bulb wall temperature The temperature at the bulb wall of a lamp, that affects lumen output and input wattage of fluorescent lamps and that is important in lighting calculations. See application thermal factor. candela (cd) A unit of luminous intensity in a given direction, equal to one lumen per steradian. candlepower (cp) The luminous intensity of a light source, as expressed in candelas. candlepower distribution curve A curve that represents the varying distribution of luminous intensity of a lamp or luminaire. cathodes See electrodes. ceiling cavity height In lighting calculations, the distance between the ceiling and the plane of the luminaires in a given space. chromaticity The measurement of a color that includes its dominant wavelength and purity.
A-2 Glossary of Terms
coefficient of beam utilization The ratio of lumens reaching a specified surface directly from a floodlight or projector to the total quantity of lumens emitted: used principally as a measurement in exterior applications. coefficient of utilization (CU) The ratio of lumens from a luminaire received on the work plane to the total quantity of lumens emitted by the lamps of that luminaire. color rendering A general expression for the effect of a light source on color appearance of objects in comparison with their appearance under a reference light source. color rendering index (CRI) A measurement of the amount of color shift that objects undergo when lighted by a light source as compared with the color of those same objects when seen under a reference light source of comparable color temperature. CRI values range up to 100. color temperature The absolute temperature of a blackbody radiator having a chromaticity equal to that of the light source (see correlated color temperature). component efficiency standards Energy efficiency codes that address the performance of lighting equipment, including lamps, ballasts, and luminaires. cones Photoreceptor cells located in the fovea of the retina and responsible for color (photopic) vision. continuous spectrum light A light source that radiates at all visible wavelengths of the electromagnetic spectrum. contrast The ratio of the luminance of an object to that of its immediate background. cornea The front portion of the eye that receives light and begins the focusing of light into the eye. correlated color temperature (CCT) A specification of the color appearance of a light source, relating its color to that of a black body radiator, as measured in Kelvins (K). CCT is a general measure of a lamp's "coolness" or "warmness." cut-off angle (of a luminaire) The angle between the vertical axis of a luminaire and the first line of sight at which the light source is no longer visible. daylighting A lighting control strategy that focuses on architectural design practice and electrical lighting controls to distribute and control natural illumination and reduce electrical energy use. demand Refers to the demand for electricity measured as the rate of energy consumption, usually in kilowatts. See peak demand. demand-side management (DSM) A series of strategies employed by utilities to manage system load by encouraging customers to manage energy in their facilities. depreciation See lamp lumen depreciation. dichroic film A coating applied to glass that reflects light of a specific wavelength while allowing other wavelengths (usually infrared) to be transmitted.
A-3 Glossary of Terms
diffuse reflection The redirection or "scattering" of incident flux over a range of angles. diffuser A device that redirects or scatters the flux it receives from a light source. diffusion See diffuse reflection. direct glare Glare resulting from insufficiently shielded light sources or areas of excessive luminance within the field of view. direct lighting The use of luminaires that distribute a high percentage of emitted light in the general direction of the surface to be illuminated. This usually refers to light emitted downward. directional lighting Light provided at the illuminated surface predominantly from a preferred direction. Common accent lighting technique. disability glare Glare that produces a degradation in visual performance and visibility. It may be accompanied by discomfort glare. discharge lamp A lamp that produces light by discharging an electric arc through a mixture of gases and gaseous metals. discomfort glare Glare that distracts or produces visual discomfort, but which does not necessarily reduce visibility or visual performance. discount rate (nominal) The rate at which future benefits or costs are discounted to present value with consideration of inflation. When a nominal discount rate is used, future benefits and costs must be quantified in inflated dollars. discount rate (real) The rate at which future benefits or costs are discounted to present value without consideration of inflation. display lighting An accent lighting technique that is intended to emphasize artwork or merchandise. Also refers to specialized lighting equipment that accomplishes this task. efficacy A measurement of the ratio of light produced by a light source to the electrical power used to produce that quantity of light, expressed in lumens per watt. Efficacy is an important determinant of energy efficiency in lighting equipment. efficiency See luminaire efficiency. electrodes Filaments located at either end of a discharge lamp that maintain an electrical arc between them. See arc discharge. electromagnetic spectrum A linear representation of all wavelengths of electric and magnetic radiation. ellipsoidal reflector A luminaire or lamp reflecting device in the shape of an ellipse which redirects light to produce a variable-edged, clearly defined beam. energy use The total energy consumed over a specific period of time, measured in kilowatt hours (kWh).
A-4 Glossary of Terms
equivalent sphere illumination (ESI) A metric comparing the illumination on a task with that which would fall on the same task if it were illuminated by a source providing equal luminance in all directions, such as that which would be provided by an illuminated sphere with the task in the center. exitance The density of light reflecting from a surface at a point, measured in lumens per square foot (formerly "footlamberts"). It is determined by multiplying the footcandles striking a diffuse reflecting surface times the reflectance of that surface. floor cavity height In lighting calculations, the distance between the workplane and the floor in a given space. fluorescent lamp A discharge lamp in which a phosphor coating transforms ultraviolet energy into visible light. footcandle (fc) A standard measurement of illuminance, representing the amount of illuminance on a surface one foot square on which there is a uniformly distributed flux of one lumen. footlambert(fl) A measurement of exitance, equal to lumens per square foot. The use of this term is no longer popular; exitance should be used instead. See exitance. fovea A region of intense visual sensitivity in the center of the eye's retina, containing only cone type photoreceptors. frequency The number of waves or cycles of electromagnetic radiation per second, usually measured in Hertz (Hz). fresnel lens A lens that produces a smooth, soft-edged, clearly defined beam of light. furniture factor In lighting calculations, a light loss factor that accounts for open-office furniture systems and other tall partitions. general lighting Lighting designed to provide a uniform level of intensity throughout a space. See also ambient lighting. glare See direct glare, disability glare, discomfort glare, reflected glare. halogen cycle The process in which a halogen gas combines with tungsten molecules that evaporate from the filament during lamp operation and deposits the molecules back on the filament. The halogen cycle, used in tungsten halogen lamps, reduces lamp lumen depreciation and increases lamp life. harmonic distortion A corruption of electrical power system characteristics created primarily by electronic rectifying circuits and high-speed switching systems. highlighting See accent lighting.
IES/IESNA The Illuminating Engineering Society of North America—a lighting technical organization devoted to lighting information and education, as well as the development of national standards.
A-5 Glossary of Terms
illuminance The density of incident luminous flux on a surface; illuminance is the standard metric for lighting levels, and is measured in lux (lx) or footcandles (fc). illuminance categories An IES recommended series of illuminance categories for a wide variety of visual tasks; used in lighting calculations to determine illuminance levels. illumination The act of illuminating or state of being illuminated. This term is often used incorrectly in place of the term illuminance to denote the density of luminous flux on a surface. incandescence The emission of visible electromagnetic radiation due to the thermal excitation of atoms or molecules. incandescent lamp A lamp in which a filament is heated to incandescence by an electric current, producing visible light. indirect lighting Lighting strategy in which a large percentage of the light emitted by luminaires is directed toward a surface (usually upward), to be reflected into the space to be illuminated. infrared (IR) radiation Invisible electromagnetic energy within the wavelength range of 770–106 nanometers; may be experienced as radiant heat. input power The maximum amount of power consumed at any one time by a luminaire-lamp-ballast combination; usually measured in watts. instant-start operation A mode of starting fluorescent lamps by applying a high voltage to the lamps without preheating the electrodes. internal rate of return A measure of economic performance representing the percentage of the initial investment that is returned each year for the life of the investment through energy savings or other benefits. inverse-square law The law of illuminance that states that the illuminance (E) at a point on a surface varies directly with the intensity (I) of a point source and inversely as the square of the distance (d) between the point and the source. At nadir, this relationship may be expressed as: E = Iy d2. isofootcandle (isolux) line A group of lines plotted on a set of coordinates to show all points on a surface where equal illuminances occur. kilowatt (kW) A unit of electric power usage, equal to 1000 watts. kilowatt hour (kWh) A measurement of electric energy. A kilowatt hour is equal to 1000 watts of power used over a period of one hour. lamp An electrically energized source of light, commonly called a bulb or tube. lamp current crest factor A ballast measure that determines the ratio of the peak lamp current to the root mean square lamp current. High lamp current crest factors reduce lamp life. lamp efficacy Ratio of lumens emitted by a lamp to its input power, measured in lumens per watt.
A-6 Glossary of Terms
lamp efficacy standard An energy efficiency standard, basing compliance on minimum lamp lumens per watt. lamp life A measure of lamp performance, as measured in median hours of burning time under ANSI test conditions. lamp lumen depreciation (LLD) The decrease over time of lamp lumen output, caused by bulb wall blackening, phosphor exhaustion, filament depreciation, and other factors. lamp starting Generic term used to describe a discharge lamp's starting characteristics in terms of time to come to full output, flicker, etc. lens A glass or plastic luminaire component used to control the direction and distribution of emitted light. light loss factor (LLF) A multiplier used in lighting calculations to account for degradation of ANSI-rated lamp lumens. Accounts for temperature and voltage variations, various depreciation factors, and environmental operating conditions. light trespass The distribution of light into unwanted areas due to a lack of shielding or beam control, or because of poor lighting design. lighting energy The quantity of electricity used for lighting, measured by multiplying connected lighting load by time of operation. lighting power density (LPD) A metric of interior lighting power use, usually measured in watts per square foot; a popular measurement in the determination of lighting energy efficiency for codes and standards. lighting power density standards Energy efficiency standards that base lighting compliance on connected lighting load in watts per square foot. line spectra light source A light source consisting of a very limited section of the visible electromagnetic spectrum, resulting in a light in which one color is dominant. louver A light source shielding device consisting of a geometrically patterned series of baffles, designed to shield or absorb unwanted light that is visible from certain angles. lumen The quantity of luminous flux emitted within a unit solid angle (one steradian) by a point source with one candela intensity in all directions. lumen maintenance A lighting control strategy that uses a photocell to detect illuminance levels in a space and maintain the lighting levels at the design illuminance level throughout the life of the lamps. Generally, this means that lamps are operated at a dimmed level when new. Over time, as lamps age and depreciation occurs, power to the lamps is gradually increased. lumen method An interior application lighting design procedure used to determine the relationship between the number and types of lamps and luminaires, the room characteristics, and the average illuminance on the workplane. Accounts for both direct and reflected light. Sometimes known as zonal cavity computation.
A-7 Glossary of Terms
luminaire A complete lighting unit, consisting of a lamp or lamps together with the components required to distribute the light, position the lamps, and connect the lamps to a power supply. Often referred to as a "fixture." luminaire dirt depreciation (LDD) A multiplier used in lighting calculations to account for the reduction in illuminance produced by the accumulation of dirt on a luminaire. luminaire efficiency The ratio of lumens exiting a luminaire to the total lumens emitted by that luminaire's lamps; expressed as a percentage. luminance The luminous intensity of a surface in a given direction per unit area of that surface as viewed from that direction; often incorrectly referred to as "brightness." luminance ratio The ratio between the luminances of any two areas in the visual field. lux (lx) A standard unit of illuminance. One lux is equal to one lumen per square meter. net present value The sum of the initial costs and all future costs and benefits, discounted to present value. neural adaptation adjustment Changes in the brain that occur when the visual system is exposed to different light levels. non recoverable light loss factors Losses in luminaire lumen output that are not due to depreciation factors. Nonrecoverable factors include ballast and thermal factors. occupancy sensing A lighting control strategy that switches lighting systems on or off based on the presence or absence of persons in a controlled space. off-peak energy use Energy consumption during off-peak hours; usually during the late evening and early morning hours. on-peak energy use Energy consumption during the period of peak demand; usually defined as early afternoon to early evening during the summer months. parabolic reflector A lighting distribution control device that is designed to redirect a luminaire's light in a specific direction. A parabolic reflector may be a component in either a lamp or a luminaire. In most applications, the parabolic device directs light down and away from the direct glare zone. In fluorescent luminaires, parabolic reflectors are often combined with louvers to minimize glare and redistribute light. With more direct light sources, such as incandescent A lamps, the reflector usually accomplishes these actions without the use of louvers. particle theory The conceptualization of electromagnetic energy as a stream of particles or "photons" traveling in a linear direction. peak demand A utility customer's maximum load. For purposes of calculating utility cost, peak demand is generally based on the maximum monthly demand, where demand is measured as an average over a time interval, usually 15 or 30 minutes. See demand.
A-8 Glossary of Terms
peak demand limiting A lighting control strategy that focuses on the gradual dimming of electric lights during times of on-peak energy use, typically from early afternoon to early evening during warm weather months. This strategy has the added benefit of reducing air-conditioning loads during these hours. phosphorescence Light emitted due to the absorption of radiation and resultant excitation; this luminescence continues for a period of time after excitation. photocell/photosensor A device that measures the amount of incident light present in a space. photometry The measurement of light quantities. photon A particle of electromagnetic radiation. photopic vision Vision produced by the cone receptors in the retina. Responsible for color vision. photopigments Chemicals within the eye whose quantities change with the amount of light entering the eye at any one time. point source A light source with dimensions that are small enough, in relation to the distance between the light source and the lighted surface, that the dimensions of the source may be excluded from calculations. Refers, in most cases, to compact incandescent or HID light sources used in applications requiring a high degree of control over the beam spread of the light source. power adjustment factor An assumed reduction in lighting power to account for the effect of automatic lighting controls. Power adjustment factors are specified in many energy efficiency standards. power draw See input power. power factor A measurement that determines how effectively input power is converted into actual usable power by an electric component such as a ballast. In AC circuits, some of the current drawn by an electrical device is wasted. Power factor is determined by computing the ratio of input watts to root mean square of the volt-amps of the electrical component. Utilities may elect to penalize customers whose electric load has a low power factor (usually less than 0.90). prime colors of light The three colors—red, green and blue—that produce white light when added together in equal proportions. prism A device that bends light through the principle of refraction. prismatic lens A lens that uses refraction to redirect light rays. pupil The adjustable aperture in the iris of the eye that regulates the quantity of light admitted into the eye. rapid-start operation A method of starting fluorescent lamps in which the ballast provides a separate winding for the constant heating of the lamp's electrodes. Rapid- start ballasts enable starting without the need for a starter switch or the application of high voltage.
A-9 Glossary of Terms
reactor ballast A ballasting device used primarily with low-wattage lamps or in high-power (non-120-volt) industrial applications. These simple inductor devices consist of a choke coil and starter, wired in series with the lamp. Some are available with power-factor-correcting capacitors. The primary advantage to using reactor ballasts is that they are inexpensive. However, they regulate lamp power poorly. recoverable light loss factors Losses in luminaire light output that can be regained through relamping and maintenance. reflectance The ratio of reflected flux to incident flux. reflected glare Glare resulting from specular reflections of high luminance in polished or glossy surface within the visual field. reflection The process by which incident flux leaves a surface from the incident side without a change in frequency. reflector A device used to direct the light from a source through the process of reflection. refraction The process by which the direction of a ray of light changes as it passes from one medium to another, due to a change in its speed. relative visual performance (RVP) A complex measurement that determines the probability (percent) of successfully performing a particular visual task under a very specific set of conditions. RVP is especially useful for assessing task visibility under conditions where speed and accuracy are important to successful visual performance. re-strike time A delay in lamp starting that occurs after a momentary power interruption; applicable to all high-intensity discharge lamps, as well as to cathode cutout fluorescent lamps. retina The cell lining at the back of the eye containing photoreceptors (rods & cones) and nerve cells that link to the optic nerve. rods Photoreceptor cells located in the retina and very responsive to low levels of light. room cavity height In lighting calculations, the distance from the workplane to the plane of the luminaires. room cavity ratio (RCR) In lighting calculations, a measure of room proportion as determined by dimensions of length, width, and height. room surface dirt depreciation (RSDD) A light loss factor produced by the accumulation of dirt on room surfaces. scheduling The controlling of electric light through the use of manual or automatic switching. scotopic vision Vision produced by the eye's rod receptors. Enables the eye to discern black and white contrast—also referred to as night vision. shielding The blocking of a light source from direct visibility.
A-10 Glossary of Terms
simple payback A measure of economic performance representing the number of years required for the monetary value of the energy savings to equal the investment. Simple payback may be adjusted to consider other annual savings and costs such as maintenance expenses. spacing to mounting height ratio The ratio of the distance between luminaires in a common space to their mounting height above the workplane. Used to help achieve uniformity of illuminance. Technically, spacing criteria (SC) provides better results. sparkle lighting A lighting design technique using point sources of light whereby the light source itself becomes the display or attraction. specular reflection The redirection of incident light without diffusion at an angle that is equal to and in the same plane as the angle of incidence. steradian A unit solid angle on the surface of a sphere equal to the square of the sphere's radius. sweeping The automatic switching off of lights throughout an entire building at a preset time or times. task lighting Lighting that is directed to a specific surface or area to provide illumination for visual tasks. task-ambient lighting A combination of task and ambient lighting designed so that the level of ambient light is less than and complementary to the task lighting. time of use, time of operation A time measure that is multiplied by the measure of connected power to quantify energy use. transient adaptation The process by which the eye adjusts to different levels of illuminance while moving from space to space. transmission The process whereby incident flux passes through a surface or medium to emerge on another side—a characteristic of transparent or translucent materials, such as glass and plastic. transmittance The ratio of transmitted flux to incident flux. troffer A common recessed luminaire type, usually installed with the opening flush with the ceiling. tuning The control of electric light through the use of dimming equipment. ultraviolet (UV) radiation Invisible electromagnetic radiation within the wavelength range of 10 to 380 nanometers. veiling luminance A luminance superimposed on the retinal image which reduces its contrast, resulting in decreased visibility and visual performance; produced by areas of increased intensity in the visual field. veiling reflection A reflection on the visual task that obscures visibility by reducing contrast (see veiling luminance). vertical footcandles A measurement of illuminance intensity on a vertical surface, such as a wall or billboard.
A-11 Glossary of Terms
visible light Electromagnetic radiation within the wavelength range of 380–770 nanometers. visual comfort The absence of discomfort glare within the visual field. visual comfort probability (VCP) A lighting system rating metric that determines the probable percentage of people who would find the lighting to be free of discomfort glare, when viewed from a specified location and in a specified direction. visual field The location of objects or points in space that can be perceived when the head and eyes are kept stationary. visual performance An assessment of the ability to perform a visual task, taking speed and accuracy in account. visual surroundings All portions of the visual field with the exception of the visual task. visual task The details and objects that must be seen for the performance of a given activity; this includes the immediate background of the details or objects. watt (W) A unit used to measure electric power. One watt equals one joule/sec. wave theory The conceptualization of electromagnetic energy moving from a source of origin in the shape of a wave. wavelength The distance between two successive points of a periodic wave, in which the oscillation has the same phase; for electromagnetic radiation, the distance is generally measured in micrometers or nanometers. wayfinding The placement of luminaires so as to define the location of pathways, doors, etc. workplane The plane at which work is usually performed and on which illuminance is calculated and specified; generally assumed to be a horizontal plane at desk height (0.76 meters [30"]).
A-12 B BIBLIOGRAPHY
EPRI Reports and Fact Sheets
Lighting Bulletins, Handbooks, and Reports
The Value of Lighting System Maintenance, MI-101838, 9/92
Visual Display Terminal Lighting, MI-101855, 3/93
Lighting Quality, MI-101857, 3/93
It Pays to Turn Off the Lights, MI-102565, 4/94
Lighting Systems Performance, MI-102565, 4/94
Calculating Lighting and HVAC Interactions for Commercial Offices, MI-103646, 4/94
Retrofitting Four-Lamp Troffers, MI-105193, 4/95
How Many Footcandles Do I Really Need? MI-105223, 8/95
Leased Outdoor Lighting, MI-107067, 10/96
LED Exit Signs, MI-108325, 6/97
Electronic Ballasts Prove Successful in Healthcare Facilities, MI-108352, 6/97
Advanced Lighting Technologies for Health Care, MI-108407, 7/97
Electrodeless Lamps and their Applications, MI-108400, 7/97
Lighting Controls: Lessons from the Field, MI-108399, 7/97
Selecting Outdoor Luminaires, MI-109752, 1/98
Lighting the Office Environment, EPRI Journal Reprint, JR-105556, 5/95
B-1 Bibliography
Commercial Lighting Efficiency Resource Book, CU.7427, 9/91
Performance Evaluation of Energy-Efficient Lighting and Office Technologies in New York City, TR-108366, June 1997
Lighting Fundamentals Handbook, TR-101710, 12/92
Lighting Controls: Patterns for Design, TR-107230, 12/96
Daylighting Design: Smart and Simple, TR-109720, 12/97
Applications
Photoelectric Control of Daylighting-Following Lighting Systems, Report CU.6243, 3/89
1994 Commercial DSM Survey (Including Utility Lighting Programs), TR-105685, 11/95
Advanced Lighting Guidelines, TR-101022-R1, 5/93
Videotapes
Office Lighting Design, EM86-05, 5/86
Brochures
Retrofit Lighting Technologies, CU.3040R1, 4/93
HID Lighting, BR-101739, 1993
Fact Sheets
Compact Fluorescent Lamps, CU.2042R, 4/93
Specular Retrofit Reflectors, CU.2046, 10/91
Occupancy Sensors, BR-100323, 4/92
Electronic Ballasts, BR-101886, 5/95
Software
LightCAD version 2.0, NATS# 7893
B-2 Bibliography
LREP version 1.0, NATS# 7939
LightPAD version 2.0, NATS# 25694
BEEM version 1.0, NATS# 18824
(Available from Electric Power Software Center (800) 763-3772)
IESNA Publications:
General
IES Lighting Handbook
IES Lighting Education:
Lighting Education Fundamentals, ED-100
Intermediate Level Lighting Course, ED-150
Lighting Mathematics, ED-200.1-88
Recommended Practices
Office Lighting (Incorporates RP-24 Recommendations; ANSI Approved), RP-1-93
Educational Facilities Lighting, RP-3-88
Light Energy Management
Design Considerations for Effective Building Lighting Energy Utilization, LEM-3-87
Other Publications:
K. Johnson and R. Zavadil. “Assessing the Impacts of Non-linear Loads on Power Quality in Commercial Buildings—An Overview.” IEEE Transactions, May 1991.
R.A. Rundquist, K. Johnson, D. Aumann.“Calculating Lighting and HVAC Interactions.” ASHRAE Journal, November 1993, Vol. 35, No. 11.
“Compact Fluorescent Product Guide.” Energy User News, September 1997, Vol. 22, No. 9.
B-3 Bibliography
B. Collins, S. Treado, and M. Ouellette. “Evaluation of Compact Fluorescent Lamp Performance at Different Ambient Temperatures.” National Institute of Standards and Technology. NISTR 4935.
J. Friedman and D.E. Weigand. “Lighting Controls for Managing Energy.” Lighting Design + Application, February 1992.
“Lighting Equipment and Accessories Directory.” Lighting Design + Application, February 1994. Vol. 24, No. 2.
“Standard for Safety.” Fluorescent Lighting Fixtures, Underwriters Laboratories, Inc., Santa Clara, CA. UL 1570.
M.S. Rea. “Switch the Lights Off!” Lighting Design + Application, December 1986.
Naval Construction Battalion. “Turn Off the Lights!” Port Hueneme, January 1980, Tech Data Sheet 80-01.
S. Gould. “Utilizing Advanced Lighting Technology Options.” Stanford University, Proceedings from the Association of Energy Engineers Lighting Efficiency Congress 90, March 27–30, 1990.
R. Abesamis, P. Black, and J. Kessel, " Field Experience with High-Frequency Ballasts." IEEE Transactions On Industry Applications, September/October 1990, Vol. 26, No. 5.
American Institute of Architects. Healthy Productive Buildings: A Guide to Environmentally Sustainable Architecture.
California Energy Commission. Directory of Certified Fluorescent Lamp Ballasts and Certified Luminaire Manufacturers. April 1985 (revised).
D.K. Smith and Associates. Comparison of Light Output from Compact Fluorescent and Incandescent Lamps. Stoneham, MA.
Damon Wood, Lighting Upgrades: A Guide for Facilities Managers, UpWard Publications, Inc., ISBN: 1-57730-425-x, 1995.
Denis O'Connor. "Measuring Results for a Corporate Lighting Efficiency Program." Energy Engineering, 1993, pp. 14–23, Vol. 90, No. 6.
Douglas Myron and Ken Shelton. "Occupancy Sensors." Proceedings of the North Texas Association of Energy Engineers, May 13–14, 1991.
B-4 Bibliography
Francis Rubinstein, Automatic Lighting Controls Demonstration: Long-Term Results. Pacific Gas & Electric, July 1991. Report 008.1-91.
Joseph J. Romm, Lean and Clean Management: How to Boost Profits and Productivity by Reducing Pollution. Kodansha: New York, 1994.
J. Kessel, "Performance of Retrofit Optical Reflectors." Strategic Planning for Energy and the Environment, Fall 1990, Vol. 10, No. 2.
John L. Fetters, The Handbook of Lighting Surveys and Audits, CRC Press, ISBN: 0- 8019-8873-x, 1998.
Lawrence Berkeley Laboratory. Performance of Electronic Ballasts and Other New Lighting Equipment. Electric Power Research Institute, March 1986, EM-4510.
Lighting Research Center. Specifier Reports (series). New York, 1992–1995.
Lithonia Lighting. Specular Materials in Recessed Fluorescent Luminaires. Georgia, 1991.
Michael Siminovich and Chin Zhang. "Increasing Fixture Efficiency with Convective Venting in Compact Fluorescent Downlights." Energy Engineering, 1993, Vol. 90, No. 6, 1993, pp. 24–32.
M. Siminovitch, F. Rubinstein, and R. Whiteman. “Thermal Performance Characteristics of Compact Fluorescent Fixtures.” Lawrence Berkeley Laboratory, Proceedings from the Association of Energy Engineers Lighting Efficiency Congress 90, March 27–30, 1990.
Underwriters Laboratories, Inc. Fluorescent Lighting Fixtures. UL 1570, 1995. Describes standards for new fixtures.
Underwriters Laboratories, Inc. Electrical Construction Materials 1990 Directory, pp. 126–128 (retrofit conversion kits).
Walter Kroner et al. Using Advanced Office Technology to Increase Productivity. Center for Architectural Research, Rensselaer Polytechnic Institute, 1992, p. 4.
Associations, Societies, and Institutes
American Consulting Engineers Council (ACEC), 1015 15th Street, NW., Suite 802, Washington, DC 20006
B-5 Bibliography
American Institute of Architects (AIA), 1735 New York Avenue, N.W., Washington, DC 20006
American Institute of Plant Engineers (AIPE), 8180 Corporate Park Drive, Suite 305, Cincinnati, OH 45242
American National Standards Institute (ANSI), 11 West 42nd Street, New York, NY 10036
American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc. (ASHRAE), 1971 Tullie Circle, N.E. Atlanta, GA 30329
Association of Energy Engineers (AEE), 4025 Pleasantdale Road, Suite 420, Atlanta, GA 30340
Building Owners and Managers Association International (BOMA), 1250 I Street N.W., Suite 200, Washington, DC 20005
Certified Ballast Manufacturers Association (CBM), 1422 Euclid Avenue, Suite 402, Cleveland, OH 44115
Edison Electric Institute (EEI), 701 Pennsylvania Avenue, N.W., Washington, DC 20004
Electric Power Research Institute (EPRI), 3412 Hillview Avenue, Palo Alto, CA 94304
EPRI Lighting Information Office (LIO), 501 Fourteenth Street, Suite 200, Oakland, CA 94612
Energy Management and Controls Society, 1925 North Lynn Street, Arlington, VA 22209
Illuminating Engineering Society of North America (IESNA), 120 Wall Street, 17th Floor, New York, NY 10005-4001
Institute of Electrical and Electronics Engineers, Inc. (IEEE), 345 East 47th Street, New York, NY 10017
Institute of Environment Sciences, 940 E. Northwest Highway, Mt. Prospect, IL 60056
Institute of Industrial Engineers, 25 Technology Park, Atlanta, Norcross, GA 30092
Instrument Society of America (ISA), P.O. Box 1277, Research Triangle Park, NC 27709
B-6 Bibliography
International Association of Lighting Designers (IALD), 1133 Broadway, Suite 520, New York, NY 10010
International Association of Lighting Management Companies (IALMCO), 431 Locust, Suite 202, Des Moines IA 50309
Manufacturers of Illuminating Products, 158-11 Harvey Van Arsdale, Jr. Avenue, Room 307, Flushing, NY 11365
National Association of Electric Distributors (NAED), 45 Danbury Roda, Wilton, CT 06897
National Electric Contractors Association, Inc. (NECA), 3 Bethesda Metro Court, Suite 1100, Bethesda, MD 20814
National Electrical Manufacturers Association (NEMA), 1300 N. 17th St. Suite 1847, Rosslyn VA 22209.
National Institute of Building Science (NIBS), 1201 L Street, N.W., Suite 400, Washington, DC 20005
National Lighting Bureau (NLB), 1300 N. 17th St. Suite 1847, Rosslyn VA 22209.
National Society of Professional Engineers (NSPE), 1420 King Street, Alexandria, VA 22314-2794
The Electrification Council (TEC), 701 Pennsylvania Avenue N.W., Washington, DC 20004
Ordering Information
Electric Power Research Institute To order EPRI software, contact: 3412 Hillview Avenue Electric Power Software Center P.O. Box 10412 (800) 763-3772 Palo Alto, CA 94303 (415) 855-2411 For EPRI-member lighting support, contact: To order EPRI reports or brochures, EPRI Lighting Information Office contact: (800) 525-8555 EPRI Distribution Center Fax (510) 444 2072 207 Coggins Drive email: [email protected]
B-7 Bibliography
P.O. Box 23205 Pleasant Hill, CA 94523 For general customer systems support, (510) 934-4212 contact: FAX (510) 944-0510 Customer Assistance Center (800) 766-EPRI
B-8 C EPRI’S LIGHTING ANALYSIS TOOLBOX
EPRI, in collaboration with its utility partners, has assembled the Lighting Analysis Toolbox, an integrated set of software tools that address a number of the important issues necessary for high-quality lighting retrofits.
Lighting Audit Software: LightPAD 2.0
LightPAD 2.0 is a flexible auditing tool providing a range of capabilities—from quick estimates of a building’s lighting energy use to detailed analysis based on on-site data entry. Users can input a range of variables—such as lighting components, hourly lighting use levels, and energy rates. Alternative lighting systems can be identified and compared while still at the site. In addition, users can compare lighting power density in each space to the recommendations of ASHRAE/IESNA Standard 90.1—1989. Data can also be exported to the EPRI COMTECH program (see below) when more complex financial analyses are needed. Database tables supplied with LightPAD contain typical lighting schedules and generic fixtures with average performance and estimated cost data. Users can customize the libraries to include additional schedules, luminaires, and other data. LightPAD 2.0 is designed to run on an IBM PC operating Windows 3.1 or higher. Windows for Pen Computing 1.0 is incorporated, which supports “pen” and keyboard entry.
Daylighting Analysis: Building Energy Estimation Module (BEEM)
BEEM is a simplified computer program that predicts daylighting and window impacts on building lighting and energy economics. The program provides data to help designers decide whether to include lighting controls, such as dimmers, for daylighting and what, if any, glass and shading options are cost effective. The user inputs information about the space to be lit, such as illumination required, location, dimensions, exposure, window size, shading coefficient, and shading options. BEEM then calculates the typical daylight illumination and the cost of lighting controls to complement that illumination. It then determines measure costs and energy savings. The final result is an analysis of the cost of daylighting controls versus the savings they will yield. BEEM runs on an IBM PC or compatible under DOS.
C-1 EPRI’s Lighting Analysis Toolbox
Lighting and Other Building Systems: COMTECH
COMTECH is a DOS-based interactive screening tool for evaluating the cost impacts of a variety of building system technologies. The logic of COMTECH is straightforward: The user inputs a compact set of data, and the system determines equipment and operating costs based on the data. The input data encompasses (1) building energy-use patterns, including lighting, cooling, and heating; (2) electric and gas rate structures; (3) equipment efficiencies; and (4) measure costs. COMTECH then combines the inputs and estimates the system costs, monthly energy bills, and operating costs. The user can vary the input data, especially the equipment efficiency and costs, to formulate “what if” scenarios when considering different retrofit options. For example, to analyze a hospital considering lighting upgrades, LightPAD and BEEM can be used to identify the upgrade possibilities. Then these proposed upgrades and energy information from the other building systems are loaded into COMTECH to determine which scheme is most effective.
Lighting Evaluation System (LES)
LES is a system of intelligent software and data logging hardware that automates the process of collecting data and transforming it into useful information. The LES data loggers can be used to monitor illuminance, occupancy, electric current, temperature, and other conditions. The software will help determine the number of data loggers to install and where they should be installed. Based on short-term monitoring data, LES will develop lighting load profiles (times of day lighting is used) and determine load shapes that can be used to predict annual energy and demand savings from retrofits. LES also considers interactions with the HVAC system. LES will help develop a data collection plan from a description of the lighting system; initialize a suite of small, battery-powered data loggers; download the data at the end of the monitoring period; and automatically perform the data analysis. Data are plotted using the graphing features built into LES. The LES software runs under Microsoft Windows.
Post-Retrofit Calibration and Commissioning: Lighting Diagnostics and Commissioning System (LDCS)
The LDCS is a complete hardware and software package designed for post-retrofit commissioning and calibration of sensitive controls such as dimmers and occupancy sensors. It performs diagnostics and feasibility studies on lighting control systems through the use of short-term monitoring. LDCS streamlines diagnostics by: x structuring the procedure that specifies the lighting control systems to be tested x specifying the instrumentation or data logger requirements for the test x handling all communication with the data loggers
C-2 EPRI’s Lighting Analysis Toolbox x automatically performing calculations x presenting the data in graphic from x preparing reports for the monitoring project
LDCS can be used with dimmers to determine if the electric lights are being dimmed as the daylight level increases, and if sufficient illuminance is being maintained in the zone as the lights are dimmed. It can be used with occupancy sensors to determine if the sensors are turning lights on and off to maximize energy savings, and if an area without an occupancy sensor could benefit from one. LDCS also diagnoses lighting sweep systems. LDCS operates with Windows 3.1 or higher.
C-3
D CALCULATING ILLUMINATION LEVELS
Lighting calculations may be used as an alternative to measurements to determine lighting levels in a space and to assess whether it is overlighted or underlighted. Outdoor lighting levels can also be calculated using standard calculation methods. This appendix provides information on two methods of calculating lighting levels. x The lumen method may be used to calculate average illumination levels for interior spaces. This is the method used by LightPAD 2.0. x Point source calculations may be used to assess illumination levels for parking lots and other outdoor spaces.
A more complete presentation of lighting calculations is provided in EPRI’s Lighting Fundamentals Handbook, TR-101710 and the IESNA Lighting Handbook.
The Lumen Method
The lumen method, also called the zone cavity method, is the most widely used method for calculating interior illumination levels or determining the number of luminaires necessary to achieve a design illumination level. Lumen method calculations assume a uniform distribution of luminaires and diffuse surface reflectances for the walls, ceiling, and floor of the space. The lumen method is based on average illuminance at the workplane and does not provide information on the distribution of light within the space or the brightness of surrounding surfaces. Generally, lumen method calculations are limited to rectangular rooms; but with some modification, they can be used with L- shaped and round rooms. The lumen method offers little information about the uniformity of illumination. To overcome this limitation, luminaire manufacturers usually provide recommendations on spacing criteria or spacing-to-mounting height ratios to help insure acceptable uniformity of illumination in the space. This value is usually given along with the data contained in CU tables.
Consider a theoretical room, with 100% diffuse reflection from all the surfaces, and illuminated by luminaires capable of delivering all the lamp lumens to the work surface. The illuminance in lumens/sq. ft.(fc) at the workplane would be the sum of all the lamp lumens divided by the area of the workplane. This is the underlying basis of the lumen method and can be expressed in the following equation.
Lumens No. of Luminaires Lumens Illuminance =× = Luminaire Area Area D-1 Calculating Illumination Levels
Of course the room surfaces absorb some of the light, and some is lost in the luminaire; so an adjustment is made. This adjustment is the coefficient of utilization (CU). The CU is based on the size and shape of the room, the surface reflectances, and the design of the luminaire. Manufacturers publish tables of CUs with their product literature. Other adjustments are made as well, to account for the depreciation of light output over time, the accumulation of dirt on the luminaires and the room surfaces, and differences between rated and actual lamp lumens. These other adjustments are collectively referred to as the light loss factor (LLF). The basic equation for the lumen method then becomes:
Lumens No. of Luminaires Illuminance =× ××CU LLF Luminaire Area Lighting designers are usually more interested in how many luminaires are needed to deliver a specified level of illumination. For this purpose, the equation can be rearranged as shown below.
Illuminance × Area Luminaires = Lumens × CU × LLF Luminaire
Coefficient of Utilization (CU)
Coefficients of utilization are published by luminaire manufacturers in tabular form similar to Table Table D-1. A separate table for each luminaire design gives CU values based on the floor, ceiling, and wall reflectances, and the room cavity ratio (see Table Table D-1). Typical surface reflectances are 80/50/20 for the ceiling, wall, and floor respectively (shown in gray).
Table D-1 Coefficients of Utilization for 2'x4' Parabolic Troffer with Three F40T12 Lamps
Floor Reflectance 20%
Ceiling Reflectance 80% 70% 50%
Wall Reflectance 70% 50% 30% 10% 70% 50% 30% 10% 50% 30% 10%
Room Cavity Ratio
07474 74 74 73 73 73 73 70 70 70
17169 67 66 69 68 66 64 65 64 62
26763 61 58 65 63 60 58 60 58 56
36358 55 52 71 58 54 52 57 53 51
45953 50 47 58 53 49 46 51 48 46
55549 45 42 54 49 44 41 48 44 41
D-2 Calculating Illumination Levels
Room Cavity Ratio
The room cavity ratio (RCR) accounts for the fact that CU values are influenced by the size and shape of the room. For rectangular rooms the RCR can be calculated by the following equation, where H is the room cavity height, L is the room length, and W is the room width.
5 ×× H (L + W) RCR = L × W
Room cavity height is the distance from the bottom of the luminaires to the workplane. It should not be confused with the ceiling height. For recessed luminaires, the room cavity height is the ceiling height less the height of the workplane (usually 2.5 ft). Large open offices typically have an RCR of about 1.0, while private offices have an RCR of about 5.0. The larger the RCR, the more difficult it is to light the room, by virtue of its size and shape.
For "L" shaped, round, or other odd-shaped rooms the RCR equation may be generalized by substituting the perimeter (P) for (L + W) and room area (A) for L x W. This form of the equation is given as follows:
25. ××HP RCR = A
For pendant-mounted luminaires, including indirect and direct/indirect luminaires, the ceiling cavity (the space between the luminaires and the ceiling) as well as the room cavity must be considered in determining the ceiling reflectance. This and many other issues are discussed in detail in the IES Lighting Handbook.
Light Loss Factor
Light Loss Factor (LLF) is a fractional multiplier with a value between zero and one that adjusts the rated lamp lumens for depreciation of light output over time, as well as light loss due to environmental and equipment factors. Light loss factors may be recoverable or nonrecoverable.
Most recoverable light losses result from lamp lumen depreciation and the accumulation of dirt on luminaire components and room surfaces. These losses are recoverable through relamping and cleaning. Lumen method lighting calculations generally account for recoverable light losses by designing for a "maintained" illuminance level. This means that at the beginning of luminaire maintenance periods, there is an excess of light, unless special controls are employed. The design level of
D-3 Calculating Illumination Levels illuminance is reached only after lamp lumens have depreciated and dirt has accumulated.
Nonrecoverable light loss factors are created through the interactions inherent in luminaire-lamp-ballast systems. They affect lumen output throughout the life of the luminaire. The most significant examples of nonrecoverable light loss factors include the ballast factor and application thermal factor.
The overall LLF is calculated by multiplying the individual light loss factors together as shown in the following equation. A more complete description of individual light loss factors follows.
LLF = LLD u LDD u RSDD u BF u ATF u FF
Where
LLD Lamp Lumen Depreciation is the reduction of lumen output produced by bulb wall blackening, phosphor exhaustion, filament depreciation, and other factors related to the aging of lamps. Metal halide and mercury vapor lamps depreciate the most; high-pressure sodium and tungsten halogen the least. This is a recoverable factor, meaning that lumen output increases every time new lamps are installed. Common depreciation values are about 0.88 (12% loss) for RE-type fluorescent lamps and about 0.84 for standard halophosphor fluorescent lamps (see Chapter 5 for information on fluorescent lamps phosphors). If a group relamping and maintenance program is planned, a higher LLD can be assumed, and fewer lamps or luminaires may be required to provide the necessary light levels.
LDD Luminaire Dirt Depreciation is the natural accumulation of dirt on lamps, lenses, and reflecting surfaces. Obviously, the greatest reductions occur in dirty or dusty environments. This is also a recoverable factor, and more frequent cleaning will minimize the effect.
RSDD Room Surface Dirt Depreciation, another recoverable factor, is the natural accumulation of dirt on ceilings and walls. This reduces room reflectances, which in turn lowers a luminaire's CU value. This factor is usually insignificant unless indirect lighting is used; a common value for direct lighting in offices is 0.98, or 2% loss. Typical values for indirect luminaires range from .60 to .90 at RCR values of 1 or less.
BF Ballast Factor accounts for the relationship between lamps and ballasts, especially for fluorescent lighting. Ballasts are usually designed so that lamps produce slightly less than their rated output. Ballast factor is a nonrecoverable light loss. For standard "energy-saving" magnetic ballasts, the factor averages about 0.925 for standard F40T12 lamps and 0.87 for 34-watt energy saving lamps. For 32-watt T-8 lamps with instant- start electronic ballasts, 0.95 is a typical ballast factor.
ATF Application Thermal Factor accounts for the fact that lamp lumen output is very sensitive to the lamp's bulb wall temperature. Lamp lumen ratings are made under very specific ANSI operating conditions: in free, unmoving air at a temperature of 25°C (77°F). A lamp's bulb wall temperature can be significantly higher inside a luminaire. For example, in a magnetically ballasted static, lensed troffer, lumen output of 40-watt F40T12 lamps will be reduced by about 6% due to the elevated temperature. ATF varies depending on luminaire, lamp, and ballast type. Lamps operated by electronic ballasts, for instance, are somewhat less sensitive to variations in bulb wall temperature. Photometric data by luminaire manufacturers partially accounts for non-ANSI operating conditions. The Advanced Lighting Guidelines (TR-101022) provide luminaire tables that account for the effects of both the ATF and the ballast factor on lamp lumen output. See the Luminaires and Lighting Equipment chapter of that document for details.
D-4 Calculating Illumination Levels
FF Furniture Factor accounts for light loss due to open-office furniture systems and other tall partitions. In traditional office spaces without vertical partitions, the factor is 1.00 (no loss); for 60-inch tall partition systems, the factor is 0.70. This factor is nonrecoverable, unless the partitions are removed.
Point Source Calculations
Point source calculations are used primarily for determining the effect of one or more luminaires in an outdoor setting. Calculations are based on the inverse-square law of illumination. The inverse-square law says that the illuminance on a surface is inversely proportional to the square of the distance from the light source to the target. The illuminance is also dependent on the incident angle at which light strikes the surface. These relationships are shown in the following equation.
I x cos ine θ E = d2
E is the illuminance on the surface in footcandles (lux), I is the candlepower, in candelas, of the light source in the direction of the target, theta (T) is the angle of incidence, relative to normal (perpendicular), and d is the distance from the source to the surface. When the angle of incidence is zero (light is striking the target head on), the cosine of theta is 1.0 and the equation is reduced to the following.
I E = d2
The main difficulty in applying the inverse-square law is the trigonometry required to determine the distance from the light source to the target and the angle of incidence. The candlepower of the luminaire or lamp is usually available from manufacturers' literature.
Figure D-1 Terms in Inverse-Square Law
D-5 Calculating Illumination Levels
Figure D-2 Isofootcandle Diagram
Many outdoor luminaire manufacturers provide isolux or isofootcandle diagrams, such as shown in Figure D-Error! Reference source not found., which may be used to calculate illumination levels. These diagrams can be overlaid on a site plan to show the illumination at any point on the site. With multiple luminaires, diagrams are laid on top of each other. The isofootcandle diagrams are for a specific luminaire mounting height. If the luminaire is mounted at a different height, all the values on the chart are multiplied by appropriate correction factors, also provided by the manufacturer. An advantage of using isofootcandle charts is that they account for the candlepower distribution of the luminaire in all directions.
Vertical illuminance calculations are very useful in determining the illuminance of upright objects, such as pedestrians, signs, or building entrances. One common use for this calculation is determining the illuminance necessary for a parking lot closed-circuit television security system. The vertical calculation is essentially the same as for the
D-6 Calculating Illumination Levels horizontal plane except that the process of determining the angle of incidence and the distance (d) is more complicated.
The inverse-square law works directly for point sources of illumination. It may also be used with linear sources or with area sources, but these calculations are somewhat more complex, as they require a calculation of exitance. For further information on linear source or area calculations, consult the IES Lighting Handbook.
D-7
E MEASURING ILLUMINATION LEVELS
This appendix explains the process of making illumination measurements in spaces and addresses some of the important issues. The purpose of illumination measurements is to determine the average illumination of audited spaces so that it can be compared to IESNA recommendations. If illumination levels are too high, then there may be opportunities for delamping. If illumination levels are too low, then other corrective actions should be taken.
The actual measurement of illumination levels can be quite accurate. The lumen method of estimation is rapid and fairly accurate, usually to within 15–20%, but cannot approach the accuracy of careful field measurements. Measurements, however, are more complicated, as discussed below.
As-Is Measurements vs. Initial Lumen Measurements
In lighting retrofit audits, most illumination measurements are “as-is,” which means that measurements are taken for the existing condition of the lamps and luminaires. While it is very easy to measure as-is illumination levels, if the luminaires are especially dirty and/or the lamps are beyond their rated life, measurements will be too low and comparisons against recommended illumination levels will be invalid. An experienced auditor can make adjustments for especially dirty luminaires and/or lamps that are beyond their life.
When the budget permits, a more accurate measurement method is to clean and relamp luminaires in sample spaces before taking measurements. Measuring illumination after the system is cleaned and relamped, provides a more consistent basis. Another advantage is that after the retrofit, measurements can be again made (with clean and relamped luminaires) to provide a consistent comparison. It is also easier to assess lighting quality and aesthetics. In cases where the proposed retrofit involves more than simply replacing selected components such as ballasts, the comparison also allows for the examination of the installation's workmanship, appearance, and ease of maintenance.
If the room is small, all of the luminaires should be cleaned and relamped; in a larger space, at least six luminaires nearest the measuring reference point should be cleaned and relamped. The luminaires should be thoroughly cleaned on all interior reflective surfaces; the diffuser should also be cleaned, or replaced if it is in poor condition. After
E-1 Measuring Illumination Levels new lamps are installed, they should be "burned in" a minimum of 100 hours for fluorescent lamps and 20 hours for incandescent lamps. This will stabilize output.
When measurements are made for clean and relamped luminaires, the measurement does not represent maintained illuminance as defined by IESNA. A light lumen depreciation (LLD) factor should be determined as described in Appendix D and this factor should be multiplied times the measured illuminance. Only then can the measured illuminance be compared to IESNA recommended illuminance levels.
Photometers and Calibration
The accuracy of illumination measurements can be no greater than the accuracy of the photometer you are using. Some instruments may give lower readings when their batteries are weak; make sure the batteries are fresh before taking measurements.
All photometers used for field measurements should be cosine and color corrected so that their sensitivity mimics that of the human eye. The instrument should also be recently calibrated against a photometer that is known to be accurate or verified by a calibration laboratory. Check with universities, utility lighting laboratories, museums, or testing laboratories in your area.
If you have access to a highly accurate photometer, you can calibrate your photometer by taking a series of parallel measurements with both instruments. Your readings should include a range of illumination levels ranging from 5 to 200 or more footcandles. Multiple measurements should be taken in the moderate illumination range (30 to 70 footcandles) which is the area of interest for most field measurements. Test readings should be taken with the meters side by side and the light sources in realistic positions.
Photometers are calibrated with incandescent calibration standards. When measuring illumination from other sources, use correction factors supplied by the manufacturer.
When you have comparative measurements, you should make a graph and plot the results. It is recommended that you plot the readings from the accurate photometer on the horizontal axis and the results of your photometer on the vertical access. Your graph would look something like Figure E-1.
E-2 Measuring Illumination Levels
Figure E-1 Photometer Calibration
If readings from your photometer exactly match those of the accurate or reference photometer, then all pairs of measurements will fall along a straight line on the diagonal. However, in most cases, readings from your photometer will be consistently higher or lower than the reference photometer. When this is the case, you should fit a line through the points and calculate its slope. The slope of the line is a correction factor that should be applied to readings from your photometer. That is, use a factor that will make the field photometer readings equal the reference photometer readings.
Measurement Procedures
In retrofit situations, the average illumination is less important than the actual illumination at the work surface where a given visual task will occur. Therefore, measurements should be taken at typical visual task locations.
Before taking measurements, the temperature in the space should be stabilized at its usual level and the lamps should be operated for at least one hour. A selenium detector should be exposed to ambient light for 15 minutes to compensate for cell fatigue. The
E-3 Measuring Illumination Levels performance of fluorescent systems is very sensitive to temperature variation. In addition the meter should be turned on for at least 15 minutes. When taking measurements, the surveyor should take care not to stand so close to the meter that he or she blocks available light from reaching the meter. Also be careful of light reflected by clothing. Some photometers are equipped with a detachable sensor that allows the user to remain close to the meter without shadowing the sensor.
Measurements in Daylighted Areas
When measuring illumination levels in spaces that have windows or skylights, the goal is to measure separately the light contributions from the electric lights and the daylighting source. The following steps are recommended:
1. If the space has blinds, close them as tightly as possible, turn on the lights, and measure the illuminance. This reading should represent the light contribution from electric lighting. 2. Next open the blinds, turn off the lights, and measure the illumination. This reading should represent the daylighting contribution. 3. Finally, leave the blinds open, turn on the lights, and measure the illumination. This reading is the total contribution of electric lights and daylighting. This illumination should be equal to the sum of the illumination measured in steps 1 and 2.
If the space has no blinds, a measurement of total light can be taken, followed immediately by another measurement with the lights turned off. Subtracting the second measurement from the first will give the contribution from the electric lights. This approach is usually required for spaces with skylights since skylights rarely have blinds or any other type of shading device. The method may yield poor accuracy, since a change in the electric light contribution may be small compared to the total illuminance.
Any time measurements are taken in daylighted areas with the blinds open, you should be careful to record the sky conditions. Daylight illumination can vary considerably depending on overcast conditions, time of day and season of the year. If you are only interested in the contribution from electric lights, consider making the measurements at night or the late afternoon in winters when the sun is down. Careful measurements in daylighted areas can be used to identify spaces that are good candidates for daylight dimming systems.
Task Lighting
Task lighting generally uses low-wattage luminaires to direct light to the task area. If task lighting is already used in the test space, illuminance can be measured both with and without the general lighting contribution. Task lighting alone often provides
E-4 Measuring Illumination Levels sufficient illumination for the task, allowing ambient lighting to be reduced. If the space has no task lighting, it should be considered as a possible retrofit measure, because it may allow significant energy-saving reductions in the general lighting system. Modern task lighting often makes use of compact fluorescent lamps to maximize energy savings.
E-5
F CALCULATING COST-EFFECTIVENESS
Introduction
Once you have identified lighting retrofit opportunities and estimated the annual energy savings, maintenance costs, and construction costs, you must then decide if the lighting retrofit is cost-effective. In some cases, you may want to consider more than one design alternative, in which case you will want to know which of the alternatives is the most cost-effective. This appendix provides the technical information you will need to make these assessments.
Payback Period
The most common measure of economic performance is the payback period—the period of time it takes for the savings to equal the initial investment. Payback period is based on the construction cost difference between two competing lighting systems and the resulting savings due to the more efficient system. As a result, it can only be used to compare two competing alternatives. If multiple alternatives are to be evaluated, they must all be compared to a single base case.
While easy to understand, payback period is inadequate in comparing many design alternatives, in particular systems with different lives or maintenance costs. Consider for instance two retrofit options: one with a cost of $10,000 and annual savings of $2,000 per year and a second with a cost of $5,000 and annual savings of $1,000 per year. Both have a payback period of 5 years, but which is the better investment? The inadequacies of payback period are further exposed if the two retrofit options have different lives and varying maintenance or replacement costs. While the payback calculation can be adjusted to consider utility rebates and annualized maintenance costs, more detailed economic analysis based on net present value or internal rate of return is recommended for more complex cases.
Net Present Value (Life-Cycle Cost)
Net present value is the sum of the initial costs and all future benefits and costs over the life of the system, discounted to present value. Benefits are generally assigned a positive value while costs are assigned a negative value. In comparing alternatives, the one with the highest net present value is the best investment. Net present value can be
F-1 Calculating Cost-Effectiveness used to compare several different systems and is especially useful in comparing design alternatives with different or irregular cash flows, or design alternatives with different lives.
Expenses or costs that occur in the future have a smaller value in current dollars. The rate at which future expenses or costs are discounted is the discount rate. It is the percent reduction in future benefits or costs for each year in the future. An understanding of discount rate is necessary in order to understand other measures of economic performance such as net present value, annualized cost, benefit to cost ratio, or internal rate of return.
The discount rate can be "real" or "nominal." The real discount rate is the rate at which future benefits or costs are discounted without consideration for inflation. If future expenses and costs are quantified in current dollars, a real discount rate is used. It is generally easier to quantify future benefits and costs in current dollars, so a real discount rate is commonly used in economic analysis. If future expenses and costs are quantified in inflated dollars, then a nominal discount rate should be used. The nominal discount rate is the real discount rate plus the inflation rate.
The discount rate is the rate of return that an investor typically makes or expects to make from other investment opportunities with a similar risk. It also indicates whether an investor has a short-term or long-term perspective. Investors with a short-term perspective generally have a higher discount rate, while investors with a long-term perspective have a lower discount rate. Risk must also be considered in selecting a discount rate. Since investments in efficient lighting involve little risk, the discount rate should be based on consideration of other low-risk investments such as government securities. Using this logic, if the return on investment for government securities is 8% and the general inflation rate is 5%, then an appropriate real discount rate is 3%.
A discount rate may be used to calculate the present value of future costs. The present value of a cost occurring "n" years in the future with a discount rate of "i" is obtained by multiplying the cost by a present worth factor. The present worth factor or PWF is given by the following equation: 1 PWF = ()1 + i n Tables of present worth factors may be calculated for a variety of discount rates and years into the future so that the above equation does not have to be evaluated for every case. Such a table is included as Table F-1. To calculate the present worth of a future benefit or cost, select a value from the table based on the discount rate and the number of years into the future and multiply the selected value times the future cost or benefit. Keep in mind that if the future cost or benefit is quantified in today's dollars, a real discount rate should be used. Otherwise, a nominal discount rate should be used.
F-2 Calculating Cost-Effectiveness
Energy costs or savings (like maintenance costs) also occur in the future and may need to be discounted to present value. The values in Table F-1 could be used to discount each annual energy cost, but there are easier ways. If a cost or benefit occurs as a time series, that is, the same cost or benefit occurs each year for some period of time, then the net present value of this series of costs or benefits can be determined by multiplying the first year cost times a series present worth factor (SPWF).
Table F-1 Present Worth Factors
Discount Rate Number of 1% 2% 3% 4% 5% 6% 7% 8% 10% 12% 14% 16% 18% Years 1 0.99 0.98 0.97 0.96 0.95 0.94 0.93 0.93 0.91 0.89 0.88 0.86 0.85 2 0.98 0.96 0.94 0.92 0.91 0.89 0.87 0.86 0.83 0.80 0.77 0.74 0.72 3 0.97 0.94 0.92 0.89 0.86 0.84 0.82 0.79 0.75 0.71 0.67 0.64 0.61 4 0.96 0.92 0.89 0.85 0.82 0.79 0.76 0.74 0.68 0.64 0.59 0.55 0.52 5 0.95 0.91 0.86 0.82 0.78 0.75 0.71 0.68 0.62 0.57 0.52 0.48 0.44 6 0.94 0.89 0.84 0.79 0.75 0.70 0.67 0.63 0.56 0.51 0.46 0.41 0.37 7 0.93 0.87 0.81 0.76 0.71 0.67 0.62 0.58 0.51 0.45 0.40 0.35 0.31 8 0.92 0.85 0.79 0.73 0.68 0.63 0.58 0.54 0.47 0.40 0.35 0.31 0.27 9 0.91 0.84 0.77 0.70 0.64 0.59 0.54 0.50 0.42 0.36 0.31 0.26 0.23 10 0.91 0.82 0.74 0.68 0.61 0.56 0.51 0.46 0.39 0.32 0.27 0.23 0.19 11 0.90 0.80 0.72 0.65 0.58 0.53 0.48 0.43 0.35 0.29 0.24 0.20 0.16 12 0.89 0.79 0.70 0.62 0.56 0.50 0.44 0.40 0.32 0.26 0.21 0.17 0.14 13 0.88 0.77 0.68 0.60 0.53 0.47 0.41 0.37 0.29 0.23 0.18 0.15 0.12 14 0.87 0.76 0.66 0.58 0.51 0.44 0.39 0.34 0.26 0.20 0.16 0.13 0.10 15 0.86 0.74 0.64 0.56 0.48 0.42 0.36 0.32 0.24 0.18 0.14 0.11 0.08 16 0.85 0.73 0.62 0.53 0.46 0.39 0.34 0.29 0.22 0.16 0.12 0.09 0.07 17 0.84 0.71 0.61 0.51 0.44 0.37 0.32 0.27 0.20 0.15 0.11 0.08 0.06 18 0.84 0.70 0.59 0.49 0.42 0.35 0.30 0.25 0.18 0.13 0.09 0.07 0.05 19 0.83 0.69 0.57 0.47 0.40 0.33 0.28 0.23 0.16 0.12 0.08 0.06 0.04 20 0.82 0.67 0.55 0.46 0.38 0.31 0.26 0.21 0.15 0.10 0.07 0.05 0.04 21 0.81 0.66 0.54 0.44 0.36 0.29 0.24 0.20 0.14 0.09 0.06 0.04 0.03 22 0.80 0.65 0.52 0.42 0.34 0.28 0.23 0.18 0.12 0.08 0.06 0.04 0.03 23 0.80 0.63 0.51 0.41 0.33 0.26 0.21 0.17 0.11 0.07 0.05 0.03 0.02 24 0.79 0.62 0.49 0.39 0.31 0.25 0.20 0.16 0.10 0.07 0.04 0.03 0.02 25 0.78 0.61 0.48 0.38 0.30 0.23 0.18 0.15 0.09 0.06 0.04 0.02 0.02 26 0.77 0.60 0.46 0.36 0.28 0.22 0.17 0.14 0.08 0.05 0.03 0.02 0.01 27 0.76 0.59 0.45 0.35 0.27 0.21 0.16 0.13 0.08 0.05 0.03 0.02 0.01 28 0.76 0.57 0.44 0.33 0.26 0.20 0.15 0.12 0.07 0.04 0.03 0.02 0.01 29 0.75 0.56 0.42 0.32 0.24 0.18 0.14 0.11 0.06 0.04 0.02 0.01 0.01 30 0.74 0.55 0.41 0.31 0.23 0.17 0.13 0.10 0.06 0.03 0.02 0.01 0.01
F-3 Calculating Cost-Effectiveness
Table F-2 Series Present Worth Factors
Discount Rate
Number of 1% 2% 3% 4% 5% 6% 7% 8% 10% 12% 14% 16% 18% Years
1 0.99 0.98 0.97 0.96 0.95 0.94 0.93 0.93 0.91 0.89 0.88 0.86 0.85
2 1.97 1.94 1.91 1.89 1.86 1.83 1.81 1.78 1.74 1.69 1.65 1.61 1.57
3 2.94 2.88 2.83 2.78 2.72 2.67 2.62 2.58 2.49 2.40 2.32 2.25 2.17
4 3.90 3.81 3.72 3.63 3.55 3.47 3.39 3.31 3.17 3.04 2.91 2.80 2.69
5 4.85 4.71 4.58 4.45 4.33 4.21 4.10 3.99 3.79 3.60 3.43 3.27 3.13
6 5.80 5.60 5.42 5.24 5.08 4.92 4.77 4.62 4.36 4.11 3.89 3.68 3.50
7 6.73 6.47 6.23 6.00 5.79 5.58 5.39 5.21 4.87 4.56 4.29 4.04 3.81
8 7.65 7.33 7.02 6.73 6.46 6.21 5.97 5.75 5.33 4.97 4.64 4.34 4.08
9 8.57 8.16 7.79 7.44 7.11 6.80 6.52 6.25 5.76 5.33 4.95 4.61 4.30
10 9.47 8.98 8.53 8.11 7.72 7.36 7.02 6.71 6.14 5.65 5.22 4.83 4.49
11 10.37 9.79 9.25 8.76 8.31 7.89 7.50 7.14 6.50 5.94 5.45 5.03 4.66
12 11.26 10.58 9.95 9.39 8.86 8.38 7.94 7.54 6.81 6.19 5.66 5.20 4.79
13 12.13 11.35 10.63 9.99 9.39 8.85 8.36 7.90 7.10 6.42 5.84 5.34 4.91
14 13.00 12.11 11.30 10.56 9.90 9.29 8.75 8.24 7.37 6.63 6.00 5.47 5.01
15 13.87 12.85 11.94 11.12 10.38 9.71 9.11 8.56 7.61 6.81 6.14 5.58 5.09
16 14.72 13.58 12.56 11.65 10.84 10.11 9.45 8.85 7.82 6.97 6.27 5.67 5.16
17 15.56 14.29 13.17 12.17 11.27 10.48 9.76 9.12 8.02 7.12 6.37 5.75 5.22
18 16.40 14.99 13.75 12.66 11.69 10.83 10.06 9.37 8.20 7.25 6.47 5.82 5.27
19 17.23 15.68 14.32 13.13 12.09 11.16 10.34 9.60 8.36 7.37 6.55 5.88 5.32
20 18.05 16.35 14.88 13.59 12.46 11.47 10.59 9.82 8.51 7.47 6.62 5.93 5.35
21 18.86 17.01 15.42 14.03 12.82 11.76 10.84 10.02 8.65 7.56 6.69 5.97 5.38
22 19.66 17.66 15.94 14.45 13.16 12.04 11.06 10.20 8.77 7.64 6.74 6.01 5.41
23 20.46 18.29 16.44 14.86 13.49 12.30 11.27 10.37 8.88 7.72 6.79 6.04 5.43
24 21.24 18.91 16.94 15.25 13.80 12.55 11.47 10.53 8.98 7.78 6.84 6.07 5.45
25 22.02 19.52 17.41 15.62 14.09 12.78 11.65 10.67 9.08 7.84 6.87 6.10 5.47
26 22.80 20.12 17.88 15.98 14.38 13.00 11.83 10.81 9.16 7.90 6.91 6.12 5.48
27 23.56 20.71 18.33 16.33 14.64 13.21 11.99 10.94 9.24 7.94 6.94 6.14 5.49
28 24.32 21.28 18.76 16.66 14.90 13.41 12.14 11.05 9.31 7.98 6.96 6.15 5.50
29 25.07 21.84 19.19 16.98 15.14 13.59 12.28 11.16 9.37 8.02 6.98 6.17 5.51
30 25.81 22.40 19.60 17.29 15.37 13.76 12.41 11.26 9.43 8.06 7.00 6.18 5.52
F-4 Calculating Cost-Effectiveness
The SPWF for "n" years or periods and a discount rate of "i," can be calculated with the following equation.
()1 +−i n 1 SPWF = i ()1 + i n
Table F-2 contains precalculated series present worth factors for a variety of discount rates and years into the future. To calculate the net present value of a time series of future benefits or costs, select a value from the table based on the discount rate and the number of years into the future and multiply the selected value times the first year cost or benefit.
Benefit-to-Cost Ratio
Benefit-to-cost ratio is another way of evaluating investments. This is the ratio of the net present value of all benefits to the net present value of all costs. All investments with a ratio greater than one may be considered cost-effective. In comparing multiple investment alternatives, all would have to be compared to a base case. The one with the highest benefit-to-cost ratio is the best investment opportunity.
Internal Rate of Return
The internal rate of return (IRR) is the discount rate at which the present value of future benefits in energy savings and maintenance cost savings is equal to the initial cost premium. Put another way, it is the return on investment with all future costs and savings considered. The IRR of an investment can be viewed as the amount of annual interest (in percent) paid on the investment over the life of the project. The internal rate of return must be calculated through a process of iteration, but many spreadsheet programs have built in functions that are capable of calculating the IRR.
Annualized Cost
Annualized cost is a useful method of comparing lighting alternatives. The initial costs and periodic maintenance costs are converted to an equivalent annual payment and added to the annual energy costs. The design alternative with the lowest annual cost is the one that is most cost-effective. Annualized cost is especially useful when initial costs are financed. Like IRR, annualized cost can be calculated with spreadsheet programs.
F-5 Calculating Cost-Effectiveness
Other Issues
Inflation and Energy Cost Escalation Rates
The price of all goods and services increases over time at the general inflation rate. As long as all future costs increase at the same rate, inflation may be ignored in evaluating the economic performance of investments in energy efficiency. With this approach, commonly used in economic analysis, all future costs are quantified in current dollars and discounted at a real discount rate.
If there is reason to believe that energy costs will increase at a rate different from the general inflation rate, each future energy cost should be quantified in inflated dollars and discounted to present value using a nominal discount rate.
Tax Considerations
Investments in energy efficiency have tax implications that need to be considered in detailed economic analysis. Energy costs are an expense; so when energy costs are reduced, taxable income is increased and potentially some of the energy savings are paid to the government as additional taxes. On the other hand, investments in energy efficiency can be depreciated over the life of the equipment, offering a tax benefit. For many businesses, these offset each other, but they must be considered on a case-by-case basis.
F-6 G POWER QUALITY
Among the most important topics for the lighting retrofitter is power quality. All electric loads in a building affect the building's power quality. However, with a growing percentage of loads exhibiting nonlinear current consumption, utilities and users have expressed concerns over the power quality delivered throughout a building. This is particularly true for sensitive electronic loads, such as computers and peripherals.
Power quality issues affect lighting retrofitters in at least three ways. First, many engineers and most utility incentive programs require that lighting retrofit equipment meet minimum standards for power factor and harmonic distortion. Second, advanced lighting components such as electronic ballasts and control equipment can be very sensitive to incoming variations in voltage. Third, electronic ballasts can affect other sensitive equipment which impedes use of new ballasts.
Power quality concerns that must be included when evaluating lighting retrofit options include harmonic distortion, power factor, and voltage fluctuations. Sample specifications contained herein address these issues and are intended to promote the use of equipment that meets or exceeds utility standards for power factor and harmonic distortion.
Supply Voltage
The most basic power quality issue concerns a building's supply voltage. Fluctuations in supply voltage occur in four different ways, all of which affect electrical components, as well as overall building power quality.
Voltage Regulation
Variance between supply voltage and intended design voltage, caused by poor voltage regulation, is a primary concern for manufacturers and specifiers of lighting and other electrical components. Most modern electrical components are designed to operate with a very specific supply voltage. When supply voltage varies from intended design voltage by 5% or more, adverse effects may result. These include short incandescent lamp life, overheating of motors and transformers, and other damage to electrical components.
G-1 Power Quality
Voltage Transients
Voltage transients, commonly known as "spikes," are brief periods of extremely high voltage. Transients may be caused by lightning strikes, high-voltage line switching by the utility, or other factors. Transients are a primary cause of electronic equipment failure, as a voltage spike 10 to 20 times higher than the intended design voltage makes quick work of electronic components. Lighting components that suffer from voltage transients include electronic ballasts, dimmers, and other devices that use solid-state components.
Voltage Surges and Sags
Voltage fluctuations in the form of surges and sags, are caused by utility company problems, or in some cases, the operation of large equipment in buildings. Surges and sags generally last a few seconds but can significantly affect the performance of electrical equipment.
Voltage Interruption
Interruptions in supply voltage due to brownouts, dropouts, and blackouts are caused by problems with electric power generation, transmission and/or distribution systems. Brownouts can cause serious damage to equipment and should be cause for most electric equipment to be turned off. Dropouts are short-term blackouts that can be especially damaging if frequent attempts to restore power produce voltage transients.
Fluctuations in building supply voltage have been a concern ever since the advent of the mainframe computer. As such, since the 1960s it has been common practice to design power isolation conditioners and uninterruptable power supplies (UPS) for mainframe computers. UPS systems are also popular peripherals for critical computer systems such as network file servers, where they can prevent damage and data loss due to sags, dropouts, and brownouts. For personal desktop-type computers, surge and transient suppressers and compact unit UPS systems are commonly used to guard against voltage fluctuation problems.
A paradoxical feature of UPS systems, conditioners, suppressers, and the devices they are designed to protect is that these components are notorious for having relatively poor power factor along with correspondingly high levels of harmonic distortion. As such, they actually contribute to a degradation of overall building power quality, even as they guard against its more debilitating effects to the individual load.
G-2 Power Quality
Power Factor
A large percentage of the electrical load in modern buildings is accounted for by inductive devices, such as motors, transformers, and fluorescent lighting systems. In addition to the working power (kW) required to perform the actual electrical work, inductive loads consume reactive power, measured in kilovolt-amperes-reactive (kVAR). Reactive power sustains the electromagnetic field that nonlinear electrical loads require. As such, although kVAR loads perform no specific work function, they combine with kW to determine the amount of apparent power (kVA) that the utility must deliver to the facility.
Power factor refers to the ratio of working power (kW) consumed by an electrical device to the apparent power (kVA) delivered to it. Electrical loads that have relatively low power factors are inefficient in that they draw excessive current in proportion to the working power they require. For example, a 20-watt compact fluorescent lamp ballast with a low power factor of .40 actually requires 50 VA of current to energize the device. Thus, the electrical utility must supply more than twice the current than would be required for a more efficient component. In comparison, a high power factor (HPF) ballast with a power factor of 0.90 or better for the same lamp would require only about 22 VA to accomplish the same task.
If a significant proportion of a building's electrical requirement is represented by low power factor devices, the electrical distribution system must be oversized to handle the resultant larger currents and avoid overloading and overheating components. Similarly, branch circuiting and overcurrent protection must be sized accordingly. In a worst case scenario, excessively low building power factor can cause voltage drop or sag, causing sensitive electrical components to fail.
With lighting equipment, power factor is a potential concern for all discharge lamp- ballast systems, such as fluorescent and HID components. Fortunately, most modern fluorescent and HID lighting components are now available with HPF ballasts. HPF ballasts have power factors of 0.90 or better. With the 277V components common in commercial applications, HPF ballasts are the rule, rather than the exception. Nevertheless, many 120V lighting components are equipped with "normal" power factor (NPF, PF # 0.50) ballasts as standard equipment. This is particularly common with compact and low-wattage HPS fluorescent luminaires, where, in many cases, HPF ballasts are available only as an added-cost option.
Harmonic Distortion
Harmonic distortion refers to harmonic frequencies that are higher multiples of the fundamental frequency (60 Hz in 120V AC systems). These frequencies superimpose themselves on the purely sinusoidal wave form, resulting in what some plant engineers
G-3 Power Quality refer to as "dirty power." Harmonic distortion is usually associated with an increase in the use of nonlinear loads. A nonlinear load refers to any electrical device whose voltage is not proportional to its current. Such devices consume current in bursts rather than constantly. This is a characteristic of electrical components that contain electronic power converters that employ solid state switching. Examples include adjustable speed drives, UPS systems, and personal computers. In addition, arcing devices, such as arc furnaces, arc welders and fluorescent lamps, draw current in a nonlinear fashion. Unlike other types of power quality problems such as surges and spikes, harmonic distortion is not a short-term phenomenon, and it cannot be controlled with suppressing devices.
There are two types of harmonic distortion: x Current harmonic distortion (CHD) is produced by any nonlinear electrical device, as described above, whose voltage is not proportional to its current. x Voltage harmonic distortion (VHD) is caused by CHD. The distorted current wave causes a distorted voltage drop in the building system services, primarily through losses in distribution transformers and ordinary wiring. The resulting system voltage is thus distorted, with effects noticeable throughout the entirety of the building.
IEEE Standard 519 permits up to 5% voltage harmonic distortion in a building. To cause this, current harmonic distortion of at least 25% of the same type and at full rated load must be present in the building. Since different harmonic distortion percentages do not add, and in fact, sometimes can cancel one another, serious voltage harmonic distortion problems are seldom encountered. But it is the growing likelihood of this potential condition that has utilities and engineers worried. Harmonic distortion is associated with several well-known problems:
1. Current harmonic distortion can cause neutral overcurrents in three phase systems. This can occur in both home-run circuits and panelboard neutrals. 2. Current harmonic distortion can cause distribution transformer overheating. The smaller the transformer, the greater the potential problem. 3. Voltage harmonic distortion can cause problems with electronic loads. Most notably, it can introduce floating and possibly even hazardous voltages on the neutral conductor.
Ordinary transformers should be derated as much as 50% if the load has high harmonic content. Transformers can be "k-rated" to match the expected harmonic load at full capacity, but most are not. In general, voltage harmonic distortion, neutral overcurrents, and transformer overheating are very likely to occur in ordinary buildings' 120/208 volt systems. It is here where the growth in computers and peripherals has been greatest and where the power systems were generally not designed for the load. Worse, the harmonic distortion of computer and peripheral loads
G-4 Power Quality tends to be the "current gulping" wave distortion common among most electronic devices, all about the same harmonic content and over 100% current harmonic distortion. In these buildings, the 277/480 volt power systems feeding fluorescent and HID systems generally have very little harmonic distortion.
G-5
H LIGHTING SURVEY FORMS
Suggested Data Structure
A great deal of information will be collected during the data collection phase of the project. It is essential that data be collected in an orderly manner. To minimize errors and speed the collection process. This appendix presents a suggested structure for organizing the data. The structure is diagrammed in Figure H-1. Each element in this diagram is a table of information to be collected. The lines connecting the tables show relationships. For instance, each record in the Spaces table includes the ID number of the project that the space belongs to. Most of the relationships are many-to-one, which means for instance, that a project can have more than one space. Many-to-one relationships are indicated with the notations “1” and “f.“ Other relations are one-to- one. For instance the relationship between Space Groups and Spaces is one-to-one. This means that there is one and only one record in the Space Groups table for each record in the Spaces table. The one-to-one relationship is indicated with the notations “1” and “1”. The recommended data structure is consistent with LightPAD 2.0.
Project
At the root of the data tree is the project itself. A great deal of general information should be collected about the project, including the name, address, phone number, etc. of the utility customer, the building, the utility representative, and the lighting retrofit auditor. The project data might also include the date of initial contact, when the audit was started, when it was finished, etc. These dates may be useful in tracking the status of multiple projects. An input form that you can copy and use in the field is provided as Figure H-2. In addition to completing the fields listed above, the auditor should make general notes and sketches as necessary to document the building.
Billing History
Utility records should be collected for the project. For each month or billing period, the peak demand (kW), electricity use (kWh), and monthly bill should be collected. Data should be collected for a minimum period of one year, but additional data should be collected if available. The utility data will be useful in determining the average or virtual electricity rate which includes consideration of time-of-use and demand charges. Data may also be useful in calibrating analysis models and in determining
H-1 Lighting Survey Forms hours of lighting operation. Figure H-3 may be used as a data input form for collecting billing history. If a flat utility rate is used, it is only necessary to fill in the “Total” columns.
Figure H-1 Suggested Data Structure
Fixture Schedule
Each building will usually have a limited number of lighting fixture types. The fixture schedule is a listing of all the unique fixtures. Preparing a fixture schedule will save time in doing the space-by-space audit since it will only be necessary to indicate the ID of the fixture when taking down information about a space. All information that is specific to the fixture will be contained in the fixture schedule. Information should include: ID (must be unique), name, input watts, housing type, lamp types, ballast type(s), number of lamps, number of ballasts, and perhaps coefficient of utilization (CU) tables. You should also photograph each unique lighting fixture. Clearly mark each photograph and include a photo reference on the schedule for each. The latter information is necessary if lighting level calculations are to be performed. Figure H-4 is a data input form that may be used for constructing the fixture schedule.
H-2 Lighting Survey Forms
Figure H-2 Data Input Form—Project
H-3 Lighting Survey Forms
Figure H-3 Data Input Form—Billing History
Figure H-4 Data Input Form—Fixture Schedule
Spaces
Collecting information at the space level is the most time consuming task. This is why it is important to identify similar spaces when possible and only audit a sample of the similar spaces. Note that similar spaces must have not only the same lighting fixtures, but also the same operating schedule. Figure H-5 shows the information to collect for each space. Data needed only if lighting level calculations are to be performed for the space are indicated with the symbol “*”.
The spaces form includes a table for entering information about lighting systems or equipment in the space. The space equipment table identifies the quantity and type of lighting equipment located in each space. Each record in the table must have the number of fixtures, the height of the fixtures above the floor, a pointer to the fixture schedule, a pointer to a schedule of lighting operation or the full-time equivalent annual lighting hours, a coefficient of utilization for the space, the luminaire dirt depreciation (which can vary from space to space) and the contribution that the
H-4 Lighting Survey Forms luminaire makes to the general illumination of the space (used in light level calculations).
Note that schedules of operation are associated with lighting equipment, not with the space in which they are located. This enables different schedules of operation for different groups of fixtures in a single space. This may be important in assessing the benefits of daylighting controls, occupant sensors, and/or other lighting control technologies.
Figure H-5 Data Input Form—Space Data
H-5
I LIGHTING EDUCATION AND LABORATORY FACILITIES
Utility-operated Centers
Lighting Design Lab The Lighting Design Lab is a multipurpose lighting 400 E. Pine St demonstration, education, and research facility located Seattle, WA near downtown Seattle. Regular educational programs Phone (206) 325-9711 and classes are offered in all aspects of lighting including IES classes and special seminars. The Lab’s mockup space Website: http:// equipped with movable ceilings is available for public and www.northwestlighting.com private projects as is the facility’s artificial sky. An extensive library including computers and technical assistance is available. Publishes the Lighting Design Lab News quarterly.
Portland General Electric Energy The Lighting Lab is a lighting-only educational and PGE Lighting Lab demonstration facility located in downtown Portland. 410 Southwest Oak IESNA classes and other special programs are offered. The Portland, OR 97204 facility’s primary asset is a fully equipped lighting Phone (503) 464-7501 education and demonstration room that is available for e-mail: lark [email protected] public or private use on a fee basis.
Pacific Gas & Electric Energy The Energy Center is a fully-equipped facility designed for Center education, demonstration and customer education, 851 Howard Street mockup, and research in all facets of building energy San Francisco, CA 94103 efficiency. Extensive programs including IESNA classes Phone (415) 973-7268 are available. Mockup facilities include two bays with e-mail: [email protected] moving ceilings, a model-making area, a heliodon, and Website: daylight modeling and testing areas. Periodic display http://www.pge.com/pec programs oriented around themes such as retrofitting are on display. An extensive library complete with computers with demonstration versions of modern software is available.
I-1 Lighting Education and Laboratory Facilities
Southern California Edison Within CTAC’s overall energy technologies facility, a Customer Technology Application complete lighting design and technology center offers Center (CTAC) equipment demonstrations, application classes, and 6090 North Irwindale Avenue consumer advice. Special classes and programs are Irwindale, CA 91702 produced for industry groups and organizations as Phone (818) 812-7380 needed. Website: http://www.edisonx.com
Energy Resource Center A demonstration, education, and conference center, the Southern California Gas Co. ERC provides programs in gas and electric technologies. 9240 E. Firestone Blvd. Downey, CA 90240 Phone (800) 427-6584 Website: http://www.socalgas.com/erc
Sacramento Municipal Utility Facility to showcase and demonstrate a wide range of District (SMUD) electric energy efficiency technologies within a state of the Energy Technology Center art office complex. Complete lighting classroom and 6301 S Street MS A226 conference facilities. Lighting library and computer Sacramento, CA 95817 education facility. (916) 732-6738 Website: http://www.smud.org/etc
Tampa Electric Energy Center Tampa Electric Company’s ETRC displays high efficiency (ETRC) technologies including lighting, foodservice, and an 3650 Spectrum Blvd. advanced technology center. It specializes in education, Tampa, FL 33612 training, information, consulting services and evaluation Phone (813) 202-1770 services.
Website: http://www.teco.net/ETRC
Carolina Power & Light Solutions The CP&L Solutions Center demonstrates innovative and Center energy-efficient technologies, including lighting power 7001 Pinecrest Rd. quality and HVAC, to CP&L customers and associates. Raleigh, NC 27613 Phone (888) 800-7599
Website: http://wwwcplc.com/solcenter
I-2 Lighting Education and Laboratory Facilities
Other utilities may have centers not listed. Contact your local utility for more information.
I-3 Lighting Education and Laboratory Facilities
Lamp Company Centers
LIGHTPOINT State-of-the-art education facility with demonstration room, Osram Sylvania, Inc. classroom, and facility for teaching vision and quality 100 Endicott St. principles. Demonstration area features company’s lamp Danvers, MA 01923 products. (508) 777-1900
General Electric Company State-of-the-art education facility with demonstration The Lighting Institute rooms, classroom, and facility for teaching vision and Nela Park, Cleveland, OH 44112 design principles. Areas feature company’s lamp (800) 255-1200 products.
Specification Centers Specification centers feature lighting classrooms offering New York, NY fundamental education and product demonstration in Chicago, IL support of regional sales activities. Atlanta, GA Los Angeles, CA
Philips Lighting State-of-the-art education facility with demonstration room, Lighting Center classroom, and facility for teaching vision and design 200 Frankilin Square Drive principles. Areas feature company’s lamp products. PO Box 6800 Somerset, NJ 08875-6800 (908) 563-3600
I-4 Lighting Education and Laboratory Facilities
Luminaire Manufacturer Centers
Cooper Lighting A 14,000 ft2 complex with multiple rooms and displays The SOURCE featuring company products. Classes of varying lengths 400 Busse Raod include general education and classes in LUXICON. Elk Grove Village, IL 60007 (708) 956-8400
Lithonia Lighting A 20,000 ft2 complex with multiple rooms and displays Lithonia Lighting Center featuring company products. Classes of varying lengths PO Box A include general education and classes in VISUAL. Conyers, GA 30207 (770) 922-9000
Canlyte Inc. Demonstration and resource facility. Classes of varying Lighting Concept Center lengths include general education and classes in GENESYS. 160 Pears Ave. Toronto, ONT CA M5R 1T2 (416) 960-1400
Prescolite Specification Center Demonstration and resource facility. Classes of varying 1251 Doolittle Dr. lengths include general education and classes in LITEPRO. San Leandro, CA 94577 (510) 562-3500
Other manufacturer have facilities. If in question, ask the manufacturer in whose products you have interest.
I-5 About EPRI
EPRI creates science and technology solutions for the global energy and energy services industry. U.S. electric utilities established the Electric Power Research Institute in 1973 as a nonprofit research consortium for the benefit of utility members, their customers, and society. Now known simply as EPRI, the company provides a wide range of innovative products and services to more than 1000 energy- related organizations in 40 countries. EPRI’s multidisciplinary team of scientists and engineers draws on a worldwide network of technical and business expertise to help solve today’s toughest energy and environmental problems. EPRI. Electrify the World
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