sign in sign up
<<
Home , Electric arc, Fluorescent lamp

APPLICATION NOTE An In-Depth Examination of an Energy Summary Efficiency Fluorescent is the preferred system for general lighting in many commercial applications. Many types of ballasts, , and fixtures are avail- Efficient Lighting able for energy-efficient, cost-effective, high-quality installations. This Applica- tion Note reviews these components, Using Full-Size including their operating characteristics Fluorescent Lamps and application. Full-sized fluorescent systems (those and Fixtures with lamps an inch or more in diameter) can be optimized in a number of ways. Simply removing lamps in overlit areas often yields large energy savings and rapid paybacks. The right -ballast combination can improve efficiency sig- nificantly. For example, nearly any facil- ity using magnetic ballasts and T12 lamps can be retrofitted with electronic ballasts and T8 lamps for energy sav- Summary ...... 1 ings. Improving fixtures so that is distributed efficiently can also reduce How This Technology Saves energy use as well as improve visual Energy ...... 2 comfort. Types of Energy-Efficiency Measures ...... 3 Energy savings of 50 to 80 percent are possible with retrofits of old fluorescent Applicability ...... 8 systems. Designs for new construction can also be significantly more efficient Field Observations to Assess than conventional practice. Continued Feasibility...... 9 energy savings can be assured by proper maintenance, including a pro- Estimation of Energy Savings ...... 11 gram of inventory control, and a well- Cost and Service Life ...... 11 designed operation and maintenance program that includes relamping and Laws, Codes, and Regulations...... 13 cleaning schedules. Definitions of Key Terms ...... 14 References to More Information...... 15 Major Manufacturers ...... 15

Copyright © May 1997, Pacific and Electric Company, all rights reserved. Revised 4/25/97 visible , or “fluoresce.” About 22 How This Technology percent of the energy used by the lamp Saves Energy is converted to light. Altering the phos- phors produces different qualities of light. A fluorescent lighting system (Figure 1) consists of a line and/or low- While several mechanisms exist to voltage controls to the 1 strike the arc, all fluorescent lamps use on/off or dim them; a ballast , which is a a power conditioning device called a power regulator; a lamp which gener-

20a Lighting Circuit (480/277v or 208/120v)

Line Voltage Ballast Switching Breaker Panel

Lamps Other Other Switched Lights on Other Zones Switch Lighting Circuits Low Voltage Controls (Timers, Occupancy, Dimming, etc.)

Figure 2: Schematic of Fluorescent Lighting System (Source: E Source) ates light; and a fixture that houses the ballast which amplifies line voltage to lamp and determines distribution of the start the lamp, and limits current to light. A luminaire is a complete lighting maintain its arc. Ballasts also ensure unit including lamp(s), ballasts, reflec- control and safety in a variety of failure tors, and shielding and diffusion com- modes. For optimum performance, a ponents. particular ballast must match a specific lamp’s current requirements. The basic contains low-pressure vapor and inert Visible in a partially evacuated glass tube (Figure 2) lined with specially for- UV Photon mulated compounds called . - + - + - The action of an in this at- - Hg + mosphere causes the phosphors to emit - +

1 Bold italicized words are defined in the section Figure 1: Fluorescent Lamp titled “Definition of Key Terms” Operation (Source: E Source)

PG&E Energy Efficiency Information© “Full-Size Fluorescents” Page 2 Three different methods can start fluo- lamps in the fixture. The fixture may be rescent discharge in lamps. With a few below the ceiling, lighting ceiling and exceptions, the starting method of the walls as well as floor. There may be a lamp and the ballast must match. metallized reflector in the fixture to more (Mismatches either do not start, or burn efficiently distribute the light from the out the lamp, the ballast, or both.) Pre- lamps. Instead of T12s, lamps will be heat starting is an older method that skinnier “T8” units, only one inch in di- causes flickering for several seconds ameter. The ballast will use electronic before the lamps ignites. Rapid starting switching to regulate power to the is the most common method; lamps lamps, operating at high come on within a second with only a (greater than 20,000 cycles per sec- brief . Instant starting jolts the ond). Compared to T12/magnetic tech- lamp with a high-voltage (400 to 1,000 nology, T8 lamps and electronic ballasts V) pulse that starts it in under a tenth of have better maintenance, an op- a second. timal operating that matches conditions in fixtures more Baseline Fluorescent Lighting closely, and higher intrinsic efficiency System because of the greater frequency of ex- citation in the arc. The typical or “baseline” system in commercial facilities uses 4-foot lamps in a 2’ by 4’ fixture installed in the grid of Types of Energy- a suspended ceiling. The lamps are one Efficiency Measures and one-half inches in diameter, com- monly called “F40/T12,” where “40” in- dicates nominal power consumption in Fluorescent lighting can be optimized in watts and “12” denotes diameter in several ways: correcting overlit situa- eighths of an inch. The ballast uses tions by delamping, using the highest magnetic operating at line efficacy lamp-ballast systems, and ap- frequency (60 cycles per second). Al- plying appropriate control strategies. though there are more efficient types, Each of these measures is discussed today’s magnetic ballasts are some- below. times called “energy-efficient magnetic ballasts” because they are slightly im- Savings from Reducing Over- proved from those manufactured before lighting the early 1980s. Many spaces simply have too much Energy-Efficient Fluorescent electric lighting, and substantial energy Lighting System can be saved by reducing total light output. This can be done by removing An energy-efficient fluorescent system lamps, converting 3- or 4-lamp fixtures look much like the baseline, but its to 1-, 2-, or 3-lamp fixtures, retrofitting components and configuration signifi- with lower output lamp-ballast systems, cantly reduce energy consumption. If or using dimming or other control sys- overlighting existed, there may be fewer tems. Such retrofits typically provide

PG&E Energy Efficiency Information© “Full-Size Fluorescents” Page 3 large energy savings and rapid pay- levels, with minimal energy savings and backs. Reducing light output should be a payback of nearly 5 years. done with attention to the quality of the resulting light, its distribution, surface Improving Fixture Efficiency brightness, and potential. Distributing light efficiently is as impor- Illuminance is measured in footcan- tant as generating it efficiently, and can dles, using an illuminance meter. The dramatically affect visual comfort. Illuminating Engineering Society of North America recommends typical av- Fixture efficiency refers to how well the erage illuminance levels in its Lighting unit gets the light from the lamps out of Handbook, 8th edition. If measurements the fixture. The main components of a in a space show that average levels are typical fluorescent direct downlight fix- significantly higher than these, the ture are the housing, a lens or louver space is a candidate for some kind of system, and possibly a reflector. See light output reduction. Figure 3.

Reducing overlighting saves energy and Reflector Retrofits reduces the cost of lamp and ballast re- placement. There are no disadvantages Reflectors are specially shaped retro- as long as the distribution of light is not fittable metal sheets that improve (or compromised. attempt to improve) the efficiency of and distribution of light from conventional Case Study: Light Levels Affect ceiling-mounted fluorescent downlight Efficiency Opportunities at fixtures. They can significantly decrease University Facilities the internal losses of fixtures and widen or narrow their light distribution, often At a large university, foot- meas- allowing significant energy savings from urements showed some spaces overlit delamping. and some underlit. In one building, classroom light levels exceeded 75 footcandles, and one-third of the lamps Fixture Housing were removed to reduce light to the de- sign level of 60 footcandles. With a Reflector switch to electronically ballasted T8 lamps, this resulted in energy savings of over 50 percent with a payback of under two years.

Parabolic Louver In the nearby library, however, half the ceiling-mounted fluorescent fixtures had Figure 3: Typical Fluorescent been disconnected years ago as an Downlight Fixture (Source: Metal Optics) “energy savings” measure and light lev- els were below recommendations. A ret- rofit with electronically ballasted T8 lamps increased light output to design

PG&E Energy Efficiency Information© “Full-Size Fluorescents” Page 4 Reflectors are available from over two goal to achieve, and is less a function of dozen manufacturers. Innovative de- how good the reflector is than how bad signs, mounting methods, and usable the existing fixture is. In any application, lamp combinations have improved per- delamping should be considered care- formance and simplified installation, and fully, bearing in mind that it may also be many millions of square feet of space possible to delamp without a reflector. have been upgraded using them. A typi- cal retrofit, including labor, costs about Case Study: Reflector Retrofit. In $75 per 2’ x 4’ fixture. 1986, the Facilities Management Office of Columbia University renovated its Understanding reflector technology is ceiling lighting to improve energy effi- simplified by remembering a few rules: ciency. The retrofit included delamping and adding specular reflectors to en- · Reflector design—not material—is hance the light reaching the workplane. the key to performance. One lamp was removed from each of the three-lamp 2 x 4 recessed fixtures, · Highly efficient reflectors often re- and the single-lamp magnetic ballast quire relocation of existing lamps to serving it was disconnected. One of the avoid glare and provide optimal light remaining 40-watt T12 lamps was ex- distribution. changed for a Thrift/Mate® lamp equipped with a current reducer that cut · No single retrofit reflector kit will light output and remaining wattage by work well in all situations. Even in a 30 percent. The built-in building with one type of fixture, several fixtures (each using a single F40 T12 reflectors may be used, each designed lamp) were not altered. for the best pattern of light distribution for its position. Ambient light levels in the open-plan office area dropped from about 35 foot- · The potential to improve fixture (fc) to 20 to 25 fc, Levels under efficiency depends mostly on the ge- the task lights just above each desk re- ometry and efficiency of the existing mained at 120 to 150 fc. Some occu- fixture, not that of the reflector kit. pants found this contrast so great that they kept the task lights off, and used · Savings analysis of proposed ret- incandescent desk lamps instead. A rofits is best done room by room, not by more careful upgrade was pursued in fixture type throughout a large or di- late 1992. All lamps were replaced with verse facility. 3,500 K T8s, two-lamp instant-start electronic ballasts replaced the mag- · Delamping is the heart of reflector netic units, and better specular reflec- tors were installed. Task light fixtures energy savings. A frequent claim is were equipped with plug-in power re- that reflectors will allow 50 percent de- ducers that reduced light output and lamping with little or no reduction in the wattage by 50 percent. fixture’s light output. Apart from the temporarily higher lumen output of As a result, ambient light levels were newly replaced lamps, this is a difficult raised to 30 to 35 fc while task light lev-

PG&E Energy Efficiency Information© “Full-Size Fluorescents” Page 5 els dropped to 60 to 70 fc. The better smoke production, can be stabilized color rendering of the T8 lamps im- against UV degradation and costs less proved the overall appearance, and the than polycarbonate. reduced contrast between task and am- bient eased complaints of glare and ex- Louvers are used to control glare from cessive brightness. Total wattage was ceiling-mounted downlight fixtures. The cut another 20 percent. Overall payback most common type is the parabolic lou- was slightly over three years, and occu- ver, which uses carefully curved reflec- pants liked the change. tive surfaces that pass light downward but cut off any view of the lamp from Diffusers, Lenses, and Louvers other angles. Fixtures with well- designed parabolic louvers are very op- Diffusers and lenses are similar de- tically efficient, which may allow energy vices: thin sheets covering re- savings by reducing fixture counts. cessed fluorescent fixtures at ceiling However, they can also create a “dark level. They differ dramatically in effi- ceiling” effect that can make a space ciency, however. Diffusers are milky- appear gloomy, so should be specified white translucent sheets that disperse with caution. Areas that support inten- light nearly equally in all directions. sive work on video display terminals They are notoriously inefficient (VDTs) are a common application for (approximately 70 percent) because of parabolic louvers, as the dark ceiling their high light absorption. Lenses redi- effect minimizes the reflected glare in rect light rather than diffuse it, and effi- the VDTs. ciency can be as high as 95 percent. Lenses can be differentiated from dif- High-Efficiency Lamp-Ballast fusers by their clear material and micro- Systems patterns of surface prisms. There are many choices for upgrading Most lenses and diffusers are made lamps and/or ballasts in full-size fluo- from one of three types of plastic: rescent systems. The system most acrylic, polycarbonate, or . common in commercial facilities uses Many older units were made from poly- T12 lamps and magnetic ballasts. styrene because it is the cheapest. But it also has the highest flame spread and “Energy Saving” Lamps smoke production, and is unacceptable to most building codes. Polystyrene In the 1970s, manufacturers found that lenses also yellow more quickly than adding to the standard other , making them good candi- gas fill suppressed both energy con- dates for replacement during an up- sumption and light output. Thus was grade. Polycarbonate is the strongest, born the “energy saving” (ES) lamp—a ideal for outdoor and institutional fix- term that can be misleading. Lamp-only tures subject to abuse, such as in pris- efficacies are relatively high, but these ons. It is also the most expensive, and lamps are no more efficient than stan- yellows with age and exposure to UV dard magnetically ballasted T12s, and radiation. Acrylic is the choice for most electronically ballasted T8s can beat fixtures. It exhibits low flame spread and them in most cases. ES lamps now

PG&E Energy Efficiency Information© “Full-Size Fluorescents” Page 6 make up a substantial part of the avail- ing 60 Hz to (DC), and a able fluorescent sources. Nearly all are high-frequency inverter to convert DC to T12s, however, and they have several 20,000 Hz (or higher) current to the operational limitations. Brand names for lamp. Other solid-state components this lamp category include GE’s control or filter power to minimize har- WattMiser®, Sylvania’s Super- monic distortion, maintain a high power Saver®, ’ Econowatt, and Duro- factor, and shape the power waveform. Test’s WattSaver®. The primary attrac- tion is their drop-in energy savings po- Electronic ballasts typically cut internal tential for the multitude of existing T12 power losses 3 to 8 watts per ballast applications, especially those that are (from about 16 watts per ballast), oper- overlit. Some facility managers prefer ate lamps 10 percent more efficiently, ES “retrofits” since no ballast change is cut losses by driving more lamps per required, and thus no need for any real ballast, are less affected by temperature electrical work. A typical ES lamp-only and voltage variations, automatically retrofit costs about $7 per lamp includ- de-energize failed lamps, improve lamp ing labor, produces 15 percent energy efficiency by increasing the optimal savings with a 10 percent loss of light lampwall temperature, and eliminate output, and has a simple payback of visual flicker. These improvements can about two years. combine to create very large energy savings—up to 90 percent. ES lamps have a higher rate of lumen depreciation than standard lamps, are A typical electronic ballast/T8 lamp ret- very sensitive to operating current, and rofit using 2-lamp ballasts costs about cannot be deeply dimmed or run on low- $30 per lamp (including all materials ballast-factor ballasts (those that in- and labor), saves 35 percent of energy tentionally provide reduced light output). while boosting light output by 7 percent, They also perform poorly in cold tem- and has a payback of 4 to 5 years. Us- peratures and should not be run with ing four-lamp ballasts cuts costs further -cutout ballasts. Perhaps worst, while producing greater savings; pay- they may either impede the path to fu- back drops to under 3 years. ture upgrades (such as dimming) or give the impression that because “energy Hybrid Ballasts saving” lamps are in place, maximum Ballasts that cut out cathode heating efficiency has been achieved. When in- after starting and running the lamp vestigating ES lamps, compare rated briefly are known as hybrid ballasts. “mean lumens” with “initial lumens” to These ballasts use magnetic technology assess long-term performance, and re- to power the lamp and electronic tech- member that their primary means of nology to control power to the . wattage reduction is lower light output. (“Hybrid” is also used by some to de- Electronic Ballasts scribe discrete electronic ballasts. Here, we equate “hybrid” ballasts with cath- Fluorescent technology took a major ode-cutout operation at 60 Hz.) These leap forward with the electronic ballast, 60 Hz devices are very popular for en- using semiconductors to rectify incom- ergy savings, since they power T8 or

PG&E Energy Efficiency Information© “Full-Size Fluorescents” Page 7 T12 lamps with some of the efficiency Strategies include simple manual on-off gains of electronic ballasts while costing systems that control individual lamps significantly less. within fixtures or groups of fixtures, oc- cupancy sensor control, countdown- Light output and efficacy of hybrid bal- timer control (also called elapsed-time lasts are about 5 to 7 percent lower than ), timeclock switches, building that of equivalent electronic ballasts. energy management system strategies Hybrids are limited to two-lamp varie- such as “sweep” systems or scheduling ties, and lamps are wired in series. Most control, on-off photocell control, and sources agree that eliminating cathode step-dimming or continuous dimming heating does not reduce lamp life. How- using manual or automatic photocells. ever, combining low ballast factors with cathode cutout may reduce lamp life (just as with instant-start ballasts), Applicability because lamp current and attendant cathode heating are significantly re- duced. Hybrids also should not be used Full-size fluorescent systems are most in cold locations. appropriate for general lighting in com- mercial, institutional, and industrial Control Strategies spaces, except those with ceilings over 16 feet or so, which may be better Controls should be considered after served by high-intensity discharge establishing the correct lighting level, (HID) lighting. Several energy-efficient improving fixture efficiency, and using fluorescent options exist for virtually any high-efficiency lamps and ballasts. Like commercial lighting application. other systems, fluorescents can take Measures described above have the advantage of a multitude of control general applicability shown in Table 1. systems to create energy savings.

Energy Efficiency Measure Application Reduce lighting levels Light levels exceed IES recommendations. Install reflectors in fixture Existing fixtures provide poor light distribu- tion (too wide or narrow); delamping retrofit is contemplated; existing fixture is extremely dirty or worn. Install new acrylic lenses Old lenses worn, dirty, or yellowed, or made of inferior material (polystyrene). Install new parabolic louvers Glare is a problem for users, such as peo- ple working at video display terminals. Install electronic ballasts and T8 lamps Nearly any facility using magnetic ballasts and T12 lamps can make this change cost- effectively. Control strategies Lights after business hours or when space unoccupied; or on in brightly daylit spaces.

Table 1: Common Fluorescent System Applications (Source: E Source)

PG&E Energy Efficiency Information© “Full-Size Fluorescents” Page 8 Ballast Application Field Observations to The following are general guidelines for Assess Feasibility choosing among available ballasts: This section discusses observations · T8 lamps with non-dimming high and checks to ensure that a fluorescent frequency electronic ballasts gives system is appropriate for an application excellent energy efficiency, well- and is installed and working properly. established performance, and a wide Also covered are actions that can help variety of suppliers. Most general illumi- sustain energy savings achieved by ef- nation applications can use this simple ficient fluorescent systems. prescription. Reasonable light quality is virtually assured. With this combination, Related to Applicability technological concerns give way to questions of lighting design—mostly in- The essential factor to consider is the volving the distribution of light. task for which lighting is needed. The right lighting technology depends on the · Instant-start ballasts provide the task, level of quality desired, and best efficacy and lighting utility. In ap- amount of light required. General guide- plications for which no instant-start lines on lighting design, which are ob- products exist, or where duty cycles are servable in the field: shorter than three hours, rapid-start ballasts are the logical choice. · The eye is more sensitive to con- trast and differences in luminance · For applications that suggest than to absolute lighting levels, so good emerging , try products fluorescent design controls variations in on a small scale. Inspecting other in- luminance. stallations can be helpful, but there is no match for a trial under your specific · Lighting quality will usually be conditions, where any problems should much better served by removing show up quickly. sources of glare and veiling reflection than by supplying more light. · Developing a rigorous specifica- tion is an excellent way to protect the · Do not confuse requirements for organization purchasing the equipment. ambient lighting with the light needed on tasks. It is often more attractive, and · Third-party technical evaluations clearly more energy efficient, to main- are standard for lighting equipment; tain ambient lighting at 10 to 30 foot- any reputable supplier should be able to candles and use efficient task lighting to provide independent reports, such as raise light levels on work surfaces to the common ETL Lab tests, for their recommended levels of 50 or more foot- products. candles.

PG&E Energy Efficiency Information© “Full-Size Fluorescents” Page 9 · An easy way to check for mag- One easy field test is to check light lev- netic vs. electronic ballasts is to use a els. Many spaces simply have too much “strobe top”—typically available cheap, electric lighting, and substantial energy or free, from sales representatives of savings can be had by reducing total ballast manufacturers such as Motorola output. A simple check using a light or Magnetek. Spin the top under the meter can help determine whether a lighting system; if you see pattern lines, space has too much light. the lights are operating at 60 Hz and use magnetic ballasts that are retrofit Related to Energy Savings candidates; if the pattern is smooth with no lines, the lights use high-frequency For continued energy savings, system electronic ballasts. maintenance is essential. Maintaining light quality, output, and energy savings · Use the highest practical CRI requires three actions: () lamp when- ever possible. Objects and people not · Design systems with components only look better, but object clarity is ac- that minimize light loss over time, are tually improved. High-CRI lamps can easy to maintain, and use the fewest sometimes make up for a light level oth- types of lamps erwise considered marginal. · Train personnel in proper mainte- · Lamps with high color tempera- nance techniques, including cleaning and relamping tures at low light levels make spaces appear cold and dim. Conversely, lamps Control purchasing and inventory with low at high levels · of illumination make spaces look overly to ensure that only the right replace- colorful. Sources at about 3,500 K look ment components are available. good over a wide range of illuminances. Field observations that may indicate in- The color temperature of full-sized fluo- adequate maintenance include: rescent lamps is usually printed on the glass envelope near one of the end · Are the right replacement lamps caps. being used? Retrofits or installations using expensive lamp types for higher · There are general rules for spac- output or longer life can be thwarted in ing fixtures which help avoid major the future by unauthorized or incorrect footcandle variations within a space. replacements. Inspection can reveal if For example, placing a ceiling fixture this is taking place—one indicator is if closer than one foot to a wall creates a the color temperature of lamps does not “hot spot” on the wall. Unless there is a match. logical reason to vary lighting levels (such as merchandising), avoid vari- · Are fixtures dirty? Are several ances at task height directly below and lamps burned out and in place? This between fixtures by observing proper can reduce the amount of light and spacing. prompt occupants to add inefficient task

PG&E Energy Efficiency Information© “Full-Size Fluorescents” Page 10 lighting or take it upon themselves to kWsavings =# fixtures ´ replace a lamp—perhaps with an inap- propriate unit. (Watts / fixturebase - Watts / fixtureas-built ) ´Utilization_ factor ¸ 1,000 · Are lights on at night when no one is using the space? This might indi- cate need for a different control system, kWhsavings = kWsavings ´ hoursas-built or altered maintenance practices. ´HCIFkW

Estimation of Energy thermtakeback = kWsavings ´ 0.034 ´ hours ´HCIF / heating_ efficiency Savings heat

With good design, lighting energy use in HCIFkw and HCIFheat are the heat/cool most buildings can be cut by half to interaction factors which account for re- more than 80 percent, compared to a duced electric air conditioning loads conventional, inefficient system 10 to 30 and increased gas heating loads, re- years old. The internal lighting load in spectively, due to the decreased lighting conventional office buildings of those energy. A table of these factors is in the ages may be as much as 3 watts per program documentation. square foot. A building with more mod- ern equipment is likely to require less Utilization_factor is the ratio of “on” fix- than half that and a state-of-the-art tures to the total installed fixtures. This system may use as little as 0.5 watts per factor accounts for fixtures or lamps square foot. which are not operational due to: burned out lamps, failed ballasts, or not Standard Savings Calculation turned on.

The following equations are recom- Cost and Service Life mended for estimating energy savings from changes to the capacity of a fluo- rescent lighting system. Alternative Factors That Influence Service equations and more information con- Life and First Cost cerning such estimates can be found in the CEE program documentation filed Fluorescent lamp ballasts typically last with the CPUC. 40,000 to 100,000 hours and cost from $5 to $50 each, depending on type. Four-foot fluorescents typically cost from $1 to $10 each, although special- ties such as eight-foot very-high-output lamps can cost $20 or more. In general, prices climb for lamps with 80+ CRI or more, and for those in unusual sizes.

PG&E Energy Efficiency Information© “Full-Size Fluorescents” Page 11 Incandescent 1-3 7.5-9 Preheat

9-12 HO/VHO

7.5-15 Instant

18-20 Standard Rapid

20-24 Premium

0 10 20 30 Rated Lifetime (Thousands of Hours) These lifetimes are based on three hours of operation per start.

Figure 4: Rated Lifetimes for Fluorescent Lamp Types (Source: E Source )

Fluorescent lamp life varies according The PG&E CEE program assumption for to type. Lifetime is the statistical point at fluorescent fixtures and ballasts is 16 which 50 percent of the lamps in a given years. batch have failed. The primary issues in fluorescent longevity are the method Operation and Maintenance and frequency of starting. Fluorescent Requirements lamps fail most commonly when their cathodes, weakened by erosion through Operation and maintenance practices starting and maintaining the electric arc, strongly influence energy savings of physically break. Fluorescent lamps are fluorescent lighting systems, as noted rated at three hours of continuous op- above. Energy dollars can be directly eration per start, unlike HID lamps, lost through poor maintenance such as which are rated at 10 hours per start. failure to keep lighting controls opera- tive (which increases burn time) and Because of the impact of starting failure to relamp promptly, leading oc- method on lamp life, the different fluo- cupants to install their own (usually in- rescent groups exhibit varying lifetimes. candescent) task lighting. Figure 4 shows these ranges for a three-hour duty cycle. Lamp life may be The following are some tips from practi- reduced by 25 to 50 percent when op- tioners for maintaining energy savings: erated with low-ballast-factor electronic instant-start ballasts. “Premium” lamps · During system design, minimize the are built with heavy-duty cathodes and variety of lamps used. specific sockets. thick coatings for extended lifetimes. · Choose fixtures that use lamp- specific sockets. Typical Service Life

PG&E Energy Efficiency Information© “Full-Size Fluorescents” Page 12 · Convert lighting upgrade specifica- Minimum Efficacy Minimum tions into purchasing specifications. Lamp Group Wattage (lm/W) CRI 4-foot Medium Bipin >35 75 69 · Regularly train lighting maintenance <35 75 45 personnel. 2-foot U-shaped >35 68 69 <35 64 45 8-foot Slimline >65 80 69 · Budget and train for group relamp- <65 80 45 ing. 8-foot HO >100 80 69 <100 80 45 · Focus responsibility for lighting sys- tem maintenance on one person instead Table 2: EPACT Lamp Standards of diffusing it among several. Laws, Codes, and · General lighting maintenance tasks include: Regulations

· Lamp replacement or “relamping.” EPACT Spot relamping—lamp replacement as needed, after burnout—is often prac- The 1992 National Environmental Policy ticed. However, group relamping— Act (EPACT) legislation has a signifi- which is changing groups of lamps that cant effect on fluores- have reached about 70 percent of their cent systems. EPACT’s lamp require- rated life—will help maintain lighting ments cover many (but not all) types of quality, and usually reduces labor costs. fluorescents.

· Fixtures should be cleaned at The primary impact of these rules is to each relamping to maintain light output. increase the color rendering index (CRI) of standard and high-output cool · Lenses and lamp sockets should and warm-white lamps. Table 2 summa- be replaced at every group reballasting. rizes the EPACT standards.

· When ballasts eventually require eASHRAE 90.1 and Title 24, replacement, take care to reballast with California Code of Regulations the same types of units. Incorrect re- placement can reduce light output Under the National Energy Policy Act of and/or increase wattage. 1992, states are required to adopt ASHRAE 90.1 1989 or else demonstrate · When reballasting, fluorescent how an alternative is comparable. Title lamp sockets should also be replaced. 24, Subchapter 4 contains mandatory requirements for lighting systems and Since the last ballast replacement, it is equipment in nonresidential, high-rise likely that sockets have sufficiently oxi- residential, and hotel/motel facilities. dized to create resistance, shortening The main provisions address controls, lamp life and make starting more diffi- requirements for lighting circuitry, and cult. minimum standards for luminaires.

PG&E Energy Efficiency Information© “Full-Size Fluorescents” Page 13 input, expressed in lumens per watt. Definitions of Key Terms · Electronic Ballast: Device using · Ballast: An electrical device de- solid-state components to provide cur- signed to convert line current into the rent to a lamp at high frequency proper voltage, amperage, and wave- (typically 25,000 to 60,000 cycles per form to operate a fluorescent or high- second), producing more light using intensity discharge lamp. fewer watts than magnetic ballasts.

· Ballast Factor: The light output of a · Fluorescent Lamp: A low-pressure fluorescent lamp(s) operated on a bal- mercury electric-discharge lamp in last as a percentage of the light output which a fluorescing coating (phosphor) when operated on a standard transforms the discharge energy of an “reference” ballast. Ballasts with high electric arc into light. ballast factor put out more light from a given lamp than ballasts with low ballast · Footcandle (fc): A unit of illumi- factor. nance, equal to 1 lumen per square foot2 or 10.76 · Color Rendering Index (of a light source) (CRI): A measure of the degree · High Output (HO): Ballasts and of color shift objects undergo when illu- lamps designed to operate with 800- minated by the light source as com- milliamp current to provide greater light pared with those same objects when il- output. luminated by a reference source of comparable color temperature. CRI · High-Intensity Discharge (HID) ranges from 0 to 100. Lamps with higher Lamp: An electric-discharge lamp in CRI render colors more accurately than which the light-producing arc is stabi- lamps with low CRI. Incandescent lamps lized by wall temperature, and the arc have a CRI of 100, while fluorescent tube has a bulb wall loading in excess lamp CRIs range from about 50 to of 3 W/cm 2 . HID lamps include groups nearly 90. of lamps known as mercury, metal hal- ide, and high-pressure sodium. · Color Temperature (of a light source): The absolute temperature of a · Hybrid Ballast: A magnetic ballast blackbody radiator having a chromaticity that shuts off heat to a lamp’s elec- equal to that of the light source. Color trodes after the lamp has started. temperature is completely unrelated to CRI, and is somewhat counterintuitive in · Instant Start: A lamp and ballast that lamps with lower color tempera- system designed to start a lamp without tures appear “warmer” or redder, while preheating by providing a lamps with higher color high-voltage . appear “cooler” or more blue.

· Efficacy: The total light output of a lamp divided by the total lamp power

PG&E Energy Efficiency Information© “Full-Size Fluorescents” Page 14 · Lumen (lm): The SI unit of light out- 1616, e-mail [email protected], put. It is the light emitted through a unit web site www.cutter.com.) solid angle (1 steradian) by a point source having a of 1 candela. 4. Inter.Light electronic product and supplier database: www.light- · Luminaire: Generic term for a com- link.com. Includes more than 1500 plete lighting unit, consisting of lamp(s), lighting companies with product parts designed to distribute light from photos and catalog ordering func- the lamps, components to connect the tions. lamp to its power source, and an elec- 5. Special Report on Lighting, “Energy trical device to provide that power. User News,” September 1996. (Includes listings of manufacturers of · Magnetic Ballast: Typical fluores- ballasts, reflectors, and lamps.) cent ballast consisting of a magnetic coil and , designed to limit cur- rent and provide necessary starting voltage for fluorescent lamps. Major Manufacturers

· Very High Output (VHO): Ballasts GE Lighting and lamps designed to operate using 1975 Noble Road, #4295 1,500 milliamp current in order to pro- Cleveland, OH 44112 vide greater light output. Tel (216) 266-3947 Fax (216) 266-3381

References to More Osram Sylvania Inc Information 100 Endicott Street Danvers, MA 01923 Tel (508) 777-1900 1. E Source, “Lighting Technology At- Fax (508) 750-2089 las,” Volume 1, 1994.

2. Illuminating Society of North Amer- Advanced ica, “Lighting Handbook: Reference 10275 W. Higgins Rd. and Application,” 8th Edition, 1993. Rosemont, IL 60018 Tel (847) 390-5000 3. Information Corporation, “1997 En- Fax (847) 390-5109 ergy Products Directory, The Sour- cebook for Commercial Buildings, For more information on component 3rd Edition,” 1997. (Contact Ira Ker- manufacturers and distributors, see chin, Editor, Technologies for En- References 2, 3 and 5. Information on ergy Management, Cutter Informa- this technology can also be found by tion Corporation, 37 Broadway, Suite contacting relevant trade organizations, 1, Arlington, MA 02174-5552, tel such as the National Electrical Manu- (617) 641-5118 or (800) 964-5118, facturers’ Association and the Illumi- fax (617) 648-8707 or (800) 888- nating Engineering Society of North America.

PG&E Energy Efficiency Information© “Full-Size Fluorescents” Page 15