HUMANSCALE PRESENTS Bright Ideas—Office Lighting 101 In

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HUMANSCALE PRESENTS Bright Ideas—Office Lighting 101 With recent improvements in lighting technology and a better understanding of lighting issues, you can have the best of both worlds—reduced lighting costs and increased worker comfort and performance.

the last 40 years, much advancement has been made in the area of lighting technology. Workspaces In of the 1960s and ’70s were designed around the belief that more light leads to better visual per- CONTINUING EDUCATION formance. Thus, they typically provided more light than the job required with little or no flexibility Use the learning objectives below to focus for the user. The result was wasted energy and a variety of human-factors issues, such as eyestrain and your study as you read Bright Ideas—Office headaches. New scientific research and enhanced technologies have provided designers with smarter Lighting 101. To earn one AIA/CES Learning solutions. Unfortunately, many offices continue to use dated technology to illuminate workspaces. Unit, including one hour of health safety welfare credit, Today’s workplace calls for flexible lighting systems that support the tools of the modern office, such as monitors and notebook computers. This suggests the integration of more appropriate lighting solutions answer the questions on page 192f, then follow the into existing lighting plans, and the selection of the most advanced products for new-build situations. reporting instructions on page 230 or go to the Contin- “The more we come to understand about lighting the more we appreciate its importance. Lighting uing Education section on archrecord.construction.com projects present a significant opportunity for us to add value to our facilities and improve the workplace,” and follow the reporting instructions. says James Woods, Energy Conservation Officer for the U.S. Department of Commerce. LEARNING OBJECTIVES Office lighting design continues to move toward greater energy efficiency, while providing improvements for worker comfort and safety. This move toward environmentally responsible design can After reading this article, you should be able to: be further developed with the incorporation of task lighting into workplace lighting schemes that would • More effectively evaluate office lighting design typically use just ambient or overhead light sources. • Understand the importance of incorporating task lighting Recent research into the use of task lighting has provided evidence that incorporating positionable into an overall lighting plan light sources into individual workspaces provides many benefits with regard to energy consumption. • Identify the environmental and worker health-related Additionally, it provides individual workers the freedom to position their light sources most comfortably. benefits of certain types of task lighting “At the Department of State we’ve learned from experience that our employees feel strongly about having good lighting, and that user-controlled lighting can help our people accomplish their missions. Energy and cost savings along with improved environments give us the best of both worlds,”

Bright Ideas—Office Lighting 101.

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says Richard Tim Arthurs, Energy Policy and Conservation Officer, Office of Facilities Management Services, U.S. State Department. In the 1970s, when it came to lighting our workspace, more was better. Recent research has shown us that more is not better, and in fact not desired by most workers. Providing too much light can lead to the following: • Energy waste • Emotional and physical discomfort for the office worker due to improper illumination of the work surface and glare on reflective surfaces (such as the computer monitor) Using positionable task lighting in addition to low ambient light can lead to the following: • Improved lighting quality, comfort and control for workers • Increased energy efficiency Task lighting can provide illumination where it is most needed — on As we age, our eyes undergo several physiological changes—including the development of opacities in our lens and a reduction in pupil size—that result in our need for more light. paper-based documents — more economically than the most energy-efficient ceiling ambient light because task lighting is located closer to what’s being lit. The solution to this conflict is to lower the overall ambient lighting levels and In addition, individual workers can gain control over their lighting as appropriate provide individuals with positionable task lights to properly illuminate the read- for the task being completed. ing material on the desktop. In this way, both the monitor and documents can The monitor—document conflict be lit to appropriate levels for the tasks being performed. “The demands of differing tasks within the workplace create an obvious conflict Bulb options and energy efficiency in lighting requirements,” says researcher Alan Hedge, PhD, CPE, Director of the Today’s task lights utilize one of three primary bulb types: incandescent, halogen or Human Factors and Ergonomics Laboratory at the Cornell University Depart- compact fluorescent. Compact fluorescents burn cooler and have proven to be ment of Design and Environmental Analysis. more efficient than any other available task light source. A regular incandescent or The majority of work that most office workers perform today is a combina- halogen bulb works by heating a metal wire to a temperature at which it glows. tion of viewing a monitor and reading documents or other printed material. This requires high temperatures, relatively large amounts of energy, and creates a Yet these two tasks require significantly different levels of light. hot bulb surface. In fact, halogen bulbs can reach temperatures of 1800º and have If the ambient lighting level is set at the appropriate level for reading printed therefore been banned from many university dormitories because of their risk as a documents (20–50 footcandles), the lighting intensity will be much too high for fire hazard. A compact fluorescent bulb is a low-pressure mercury, electric-dis- proper monitor viewing (5–10 footcandles required). This leads to glare on the charge lamp in which phosphor coating transforms ultraviolet energy, created by surface of the monitor, substantial energy waste and a variety of worker produc- electric discharge, into visible light. The fluorescent bulb remains much cooler and tivity issues. However, if the ambient lighting level is brought down to a point uses less energy than the other two, while providing the same amount of light. which is appropriate for monitor viewing and movement throughout the work- The first practical electric lamp, developed by Thomas Edison in 1879, converted space, then there won’t be nearly enough light to read documents and other less than one percent of electricity into light. Today’s household incandescent bulbs paper-based reading material. convert 6–7 percent of their electrical input into light. The rest is wasted as heat. Clas- sic 4-ft fluorescent systems convert approximately 19% of their energy into light. Today’s compact fluorescent lamps, five inches in length, or less, can be 50 times Light Bulb more efficient than Edison’s original lamp and eight times more efficient than an incandescent light source capable of the same light output. For example, a 13-watt Comparison compact fluorescent task light will produce the same light output as a 75-watt Chart Incandescent Bulb Halogen Bulb Compact Fluorescent 100W 100W 26W incandescent light, burn cooler and consume only one-quarter of the electricity. As we age, we need more light to read LUMENS PRODUCED 1690 1900 1825 The older we get, the more light we need to see. Research indicates that the visual LIGHT QUALITY White/Yellowish Very bright, Available from performance of those in their 20s is about eight times better than those in their

white light warm to crisp/cool 60s, almosted four times better than those in their 50s. Those 61 and older require CRI (COLOR RENDERING INDEX) >90 >98 >84 more than 350 percent more contrast than do those in their 20s.

ENERGY CONSUMPTION 100 W 100 W 26 W

(or more due to heat) Relativeequir Contrast Required as a Function of Age

BULB TEMPERATURE 500° F 1800°F 125° F 400

BULB LIFE 1000 hrs 2500 hrs 10000 hrs ast R 350 300 COST OF BULB $0.50 $4.00 $14.00 250 BULB LIFE (ON AVERAGE) 167 Days 416 Days 1642.5 Days (4.5 Years) 200 e Contr BULBS NECESSARY 10 4 1 150 (OVER 4.5 YEARS) 100 $21.90 $21.90 $5.91 ANNUAL ENERGY COST 50 elativ 0

$103.55 $114.55 $40.6o R TOTAL COST 20-30 31-40 41-50 51-60 61-70 (OVER 4.5 YEARS) * Assuming 6 hours of usage per day at $0.10 per kilowatt-hour Source: U.S. Department of Energy Age

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desktops with energy-efficient task lights. In addition, maintenance and bulb replacement costs are less with task lighting. Research suggests that with the use of energy efficient lighting technologies, we can reduce overall electrical use for lighting by half, a move that would save over $20 billion annually and decrease powerplant emissions by millions of tons. According to the California Energy Commission, lighting accounts for 23 percent of the electricity used in the state. The actual figure may be considerably higher, say other sources. Five percent of electricity used for air condition- ing, for example, goes to eliminate heat generated by lighting. In general, however, the EPA estimates that lighting accounts for 20–25 percent of the electricity used annually in the United States. Since the 1970s, huge strides have been made in office lighting efficiency. Still, say California officials, the potential exists to reduce lighting energy use and peak demand by an additional 50 percent by 2020 while still improving the quality of lighting to the end user. Research by the U.S. Environmental Protection Agency has found that lighting for industry, offices, stores and warehouses represents from 80–90 percent of the total lighting electricity use in the United States. The Institute for Research in Construction, an arm of the National Research Council Canada, has found that if energy-efficient lighting were used everywhere it was profitable, the electricity required for lighting would be cut by 50 percent, and aggregate Despite being considered “task lights”, under-the-bin lighting solutions are a major source of glare and are not an adequate alternative to positional task lighting. national electricity demand would be reduced by 10 percent. This reduction in demand would significantly reduce power plant emissions, pollutants, This increased need for light is due to a number of physiological changes in and wastes, say federal researchers. our visual system that occur as we age. Flux, illuminance and luminance The term presbyopia means “old eye” and is a vision condition involving Total flux, in lumens, is the parameter that bulb manufacturers use when the loss of the eye’s ability to focus on close objects. Presbyopia, also referred to describing the total amount of light given off by a bulb in all directions. as farsightedness, occurs gradually over a number of years. Symptoms are usu- Lumens do not, however, tell us how much light will be received where it is ally noticeable by age 45 and continue to develop until the process stabilizes needed. Illuminance, on the other hand, tells us how much light will reach a some 10–20 years later. given surface. Illuminance is generally measured in lux: a short form for In the eye, the crystalline lens is located just behind the iris and the pupil. Tiny lumens per square meter of surface area, the metric equivalent of footcan- ciliary muscles push and pull the lens, adjusting its curvature, and thereby adjusting dles (which represent lumens per square foot). There are 10.76 lux in one the eye’s focal power to bring objects into focus. As individuals age, the lens devel- footcandle, but the lighting industry typically rounds this factor off to 10.0 ops opacities and becomes less flexible and elastic, making accommodation more for the sake of simplicity. difficult. Because these changes result in inadequate adjust- ment of the lens of the eye for various distances, objects that are close will appear blurry. The muscles which control the diameter of the pupil also deteriorate with age. This reduces the size of the pupil, and limits the range and speed with which the pupil can adjust to varying light levels. This, combined with the increased opacity of the crystalline lens, increases the amount of light necessary to achieve the same level of retinal illumination. Eyestrain and accompanying headaches, which can result from working under inadequate illumination, are aggravated by aging. Eye fatigue may result in blurry vision and dim lighting aggravates the problem. Task lighting allows us to achieve the correct levels of illumination, regardless of the task or vision requirements, by changing the distance between the light source and the lit object—closer for more light, further away for less. It also allows us to correctly position the angle of light to eliminate glare and veiling reflections. Task lighting saves eyes and energy Task lights, because they are closer to the work surface, are a considerably more effective means of lighting a desktop than are overhead fixtures. A task light using a 26-watt compact fluorescent lamp will consume far less energy to illuminate a work area than will a typical overhead lighting fixture. A work environment can Lowered ambient lighting levels for proper monitor viewing combined with task lights for proper document illumination provide maintain lower levels of overhead lighting by illuminating the right amount of light for different tasks while saving money and improving worker comfort, productivity and job satisfaction.

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Dated lighting schemes based solely on overhead fixtures provide an incomplete and inefficient Thirty years ago, standards of the Illuminating Engineers Society of lighting solution that wastes energy and has both physical and performance implications for workers. North America (IES) called for general office lighting in the range of 100–150 footcandles (1,000–1,500 lux). Huge, increasingly cubicled floorplates, often IES Illumination Categories & Recommended Values without any natural, outside illumination, were lighted, for the most part, by banks of 4-ft , ceiling-mounted fluorescent troffers (recessed fluorescent fixtures) that, in too many cases, resembled stadium floodlights in their intensity. ACTIVITY CATEGORY LUX FOOTCANDLES By 2002, nearly all office tasks were being performed on desktop computers and average ambient light levels in the American workplace declined s Indicates typical office task ------to one-third of 1970s levels. Today, ambient office lighting is likely to be in Public spaces with A 20-30-50 2-3-5 the range of 25–45 footcandles (250–450 lux), which is still far more light dark surroundings than is necessary for getting around the office or viewing a computer ------Simple orientation for short B 50-75-100 5-7.5-10 screen. According to IES, computers are best viewed in an environment temporary visits where the ambient lighting is 5–10 footcandles (50–100 lux), whereas most View CRT screen reading requires 20–50 footcandles (200–500 lux). ------s Working spaces where visual tasks C 100-150-200 10-15-20 Luminance, in candela per square meter (cd/m2 is a measure of how bright are only occasionally performed an object appears (1 cd/m2=0.29 foot-lamberts, the imperial unit for lumi------nance). Luminance is a representation of the amount of light seen by the eye. Performance of visual tasks of D 200-300-500 20-30-50 high contrast or large size Luminance is sometimes specified for critical lighting designs (e.g., IES Recom- mended Practice RP-24 for Offices with Video Display Terminals). s Read standard document, photocopy or newspaper ------However, illuminance is usually the parameter of preference because it is indirectly Performance of visual tasks of E 500-750-1000 50-75-100 related to what the eye sees. Knowing the reflectance properties of illuminated medium contrast or small size surfaces, it is possible to calculate luminance from illuminance using procedures s View photo in moderate detail; reference phone book ------in the IES Lighting Handbook. IES lighting recommendations are usually given Performance of visual tasks of F 1000-1500-2000 100-150-200 in terms of illuminance because it is more practical to measure. low contrast or very small size ------If we compare a lighting fixture to a shower head, then the lumen output, or Performance of visual tasks of G 2000-3000-5000 200-300-500 total flux, is the rate of flow of water and illuminance is the amount of water low contrast or very small size collected in a bucket at a given time. The key point is that the same total flux over a prolonged period can give different amounts of water in the bucket, simply by moving the bucket, ------Performance of very prolonged H 5000-7500-10000 500-750-1000 or by changing the spray pattern or by changing any physical obstructions and exacting visual tasks between the source and the bucket. Total flux doesn’t specify how much illumi------nance will be provided where it’s needed. This is true, in part, because the lumi- Performance of very special I 10000-15000-20000 1000-1500-2000 visual tasks of extremely low contrast naire, reflectors, lenses and other optical media can greatly affect the flow of ------light from the source to the work surface. Failure to remember this is a frequent A-C for illuminances over a large area (i.e. lobby space) D-F for localized tasks G-I for extremely difficult visual tasks cause of poor lighting design, especially in retrofit applications. For lighting designs, we should not assume that two lamps with the same lumen rating will each give the same amount of light where needed.

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Rough estimations of illuminance can be made by dividing the candelas by the High-frequency operation also reduces perceptible flicker. The health ben- square of the distance between the light source and the surface illuminated. For efits seen with electronic ballasts are attributable to the reduction in flick- example, if a fixture gives 2000 candelas in the downwards direction, and if we er as visual demands are reduced. mount that fixture in a 10-ft high ceiling, then the illuminance from that fixture will Electronic ballasts can increase the efficiency of fluorescent lighting systems be approximately 2000/102=20 footcandles at the floor directly below the fixture. by as much as 29 percent over systems using magnetic ballasts, while at the In metric units, one would calculate 2000/(3.048m)2=215 lux. Calculations of this same time extending bulb life. type work as long as the distance to the surface is at least four times greater than the Electronic ballasts are either instant start or rapid start. Instant start ballasts, maximum dimensions (i.e., length or width) of the light source. For shorter dis- which produce a high starting voltage which is then quickly reduced, are more tances, the calculations may still be used but they are subject to a greater uncertainty. energy efficient. Rapid start ballasts heat the lamp cathodes before triggering Ballast technology illumination, helping to maximize the life of the ballast and the bulb. All fluorescent lamps require ballasts, which stabilize and control the electrical Among the findings of National Research Council Canada researchers Guy current that gets sent to the lamp. These ballasts are available in two primary Newsham and Jennifer Veitch, designs utilizing electronic ballasts: types: magnetic and electronic. • resulted in workers typing 21 percent faster during creative writing exercises Magnetic ballasts use long-standing technology, and with few compo- • improved workers’ reaction times by eight percent nents susceptible to failure, they are likely to last for 20 years or more, far • lowered incidence of headaches and eyestrain longer than most electronic ballasts. However, electronic ballasts have the “Our findings provide good news for the lighting community,” they conclude. edge in performance and health considerations. Electronic ballasts are “The goals of improving energy efficiency and lighting quality are compatible. more energy efficient than magnetic ballasts because they operate lamps at People who worked under electronic ballasts…showed better visual performance, higher frequencies (above 20,000 Hz versus 60 Hz for magnetic ballasts). did better on reading and writing tasks and rated the tasks less difficult.”

SMITH GROUP: TASK LIGHTING ESSENTIAL

For Detroit-based Smith Group, Inc., an A/E firm figure excludes air-handling. the case of under-shelf lighting, the light originates with its own in-house lighting group, the goal of a “Perhaps more importantly,” Luckey says, under the shelf, hits the work surface and bounces soon-to-be-completed, nine-building campus in “ASHRAE 90.1 sets a standard of 94,842 BTUs directly into the eyes of the worker. Van Buren Township, Michigan, for auto parts sup- (British thermal units) per square foot per year. Vis- The solution, Fong says, is an “asymmetric” task plier, Visteon, was “the absolute minimization” of teon Village will consume about 59,000 BTUs per light that uses specially designed reflectors to con- energy costs, says James Luckey, AIA, Senior square foot per year—a 37 percent energy reduc- centrate light in one direction. This allows the user Design Architect. tion from the code allowance. That number includes to position the light off to the side so that the The first consideration was natural light. To under-floor heating and cooling consumption.” beams of light are directed across the front of the allow as much light as possible into interiors, Luck- “When it comes to lighting, there is a lot more user, instead of toward them. ey designed all of the 100,000–150,000-sq-ft build- to think about than most people realize,” says “If you are right-handed, an asymmetric task ings to be “extremely narrow,” 64 feet in width. “We Denise B. Fong, IALD, LC, LEED, a principal at light located to the left of your work area will put wanted this project to conform to the European Seattle-based Candela Architectural Lighting Con- the highest light output in the middle of your work standard, in which workers are never more than 10 sultants. surface, and the light will bounce away from you so meters from a window,” he says. It is not enough to rely upon standards, Fong you don’t get any glare from the lamp,” she adds. Exposures are large: sills of 15-ft-wide windows says. “One of the things we do because the energy “The most common design error, clearly, is the are only 2-ft off floors; headers are 10-ft above floor code tells us to do it, is to calculate consumption by mismatch between where light is being delivered height; ceilings at 11ft 6 in. “We like, whenever pos- watts per square foot, but that tells us little about and where people are utilizing that light,” says Alan sible, to push ceiling height,” says Luckey. the ‘quality’ of light.” Hedge. “All too often we put light into a building Ambient lighting, via direct-indirect pendants “We don’t see, for instance, what the light meter without knowing the ultimate layout. Even if the (75 percent upward, 25 percent downward), cen- measures,” says Fong. “We see reflected light. If you layout is known, things can happen that are not tered in 20-ft ceiling bays, 30 inches beneath ceil- were to meter light in a room painted half black foreseen. Offices may be partitioned differently by ings, is at 30 footcandles and is automated. “Most and half white, a light meter will give you the same new tenants, for instance, and the new layout can days, in all likelihood,” Lucky figures, “ambient reading in either space, but to our eyes, the area result in a feast or famine situation, so far as light is lighting will not be turned on.” with black surfaces will appear darker because there concerned. Some workers may complain of glare For “sparkle,” Smith used café and track lights. is less reflection.” and headaches; some may be in the dark.” Each 50-sq-ft workstation will also have at least one She suggests a growing interest in the use of task In a study conducted in 1990, Cornell compact fluorescent task light capable of providing lighting, mentioning, “Task lighting is not some- researchers drew on an American Society of Interi- 50–75 footcandles where it is needed. thing we lighting designers pay much attention to, or Designers survey in which 68 percent of employ- “The use of task lighting allows higher intensi- but there are cost benefits associated with task ees complained about the light in their offices and ties only where that level of light is needed,” says lighting. In general, the use of task lighting enables 79 percent of VDT users wanted better lighting. Luckey. “In a computer environment, the goal is to you to reduce the general ambient light level.” The Cornell study came to the conclusion that eye- minimize light pollution. This project, he says, is in “There are still a lot of projects out there where strain was the number one health hazard in the keeping with what we try to do with every project. all the lighting is in the ceiling, but energy codes are workplace—ahead of radiation, asbestos, or expo- If ceilings are shallower, we have no choice but to forcing us to rethink that strategy,” Fong says. sure to AIDS. put lights in the ceiling plane, but we prefer not to.” According to an assessment by the Lighting Hedge says eyestrain remains the number one At Visteon’s new corporate campus, which will Research Center at RPI, more than one-third of all complaint in the office environment, and the open incrementally from August through Decem- U.S. workers occupy partitioned workstations, and degree of dissatisfaction is difficult to ignore. It ber, workers not only will control lighting within under-shelf task lighting accounts for 90 percent of confirms the need to identify the best available individual workstations, but individual controls will all task lighting sold. methods of lighting. allow them to control floor-distributed heating and “If partitions are shelved, and if the task light is How essential a component is task lighting in cooling as well. beneath the shelf,” Fong says, “light is not where creating an effective office lighting scheme? “It is Overall lighting consumption, Luckey says, you need it, and glare is almost always a problem.” likely to be the most effective solution in any envi- is one watt per sq ft; lighting and miscellaneous Glare happens when the light source, the object ronment in which workers are doing both paper power consumption, 2.25 watts per sq ft—the being lit and the eyes are all in the same plane. In work and computer work,” says Hedge. I

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The color of light 100 how colored objects appear under that bulb’s light compared to their One aspect of lighting that often gets overlooked is bulb color tempera- appearance in daylight. A CRI of 100 means no difference, while a low CRI ture, which describes the color appearance of the bulb, not the object could mean a big difference. Incandescent lamps typically have CRIs above 90, being viewed. Color temperature ranges from 3000 Kelvin for “warm” but that doesn’t mean that they always give suitable results. Suppose, for exam- sources like incandescent lamps, to approximately 6500 Kelvin for “cool” ple, we wish to illuminate white cabinets in a kitchen or a hospital examination sources like daylight fluorescent. Color temperature data is readily avail- room. A design objective might be to enhance the impression of whiteness, able from lamp manufacturers. The selection of color temperature should cleanliness and sterility. In this case, the color temperature of incandescents be considered relative to the application. would be too low to achieve the desired effect. As a general rule, one should Lamps that are high to very high in color temperature (5,000K to 7,500K) therefore select color temperature first, then pick the lamp giving the optimum provide improved visual acuity compared to lower-color temperature lamps CRI for the application. (typically 3,500K) at the same light level. Visual acuity is generally defined as Most fluorescent lamps operate at 3,000K to 4,100K, with a CRI from the sharpness of vision, with normal visual acuity rated at 20/20. High color tem- low 50s to 86, but recent technology gains now give us fluorescents with CRIs perature lamps are rich in the blue portion of the color spectrum and have a above 90. A “full-spectrum” lamp is generally defined as a lamp having a Color- noticeably “cool” appearance. Rendering Index (CRI) of 90 or above and a color temperature of 5,000 degrees The Color Rendering Index, or CRI, of a bulb specifies on a scale of 1 to Kelvin or above. I

CLICK FOR ADDITIONAL REQUIRED READING The article continues online at: archrecord.construction.com/resources/conteduc/archives/0409human-1.asp. To receive AIA/CES credit, you are required to read this additional text. For a faxed copy of the material, contact Humanscale Customer Service at (800) 400-0625 or via email at [email protected]. The following quiz questions include information from this material.

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LEARNING OBJECTIVES 5. According to the California Energy Commission, lighting accounts for • More effectively evaluate office lighting design what percentage of the electricity used in the state? • Understand the importance of incorporating task lighting into an overall a. 7 percent lighting plan b. 13 percent • Identify the environmental and worker health-related benefits of certain c. 23 percent types of task lighting d. 35 percent INSTRUCTIONS 6. Today’s household incandescent bulbs convert what percentage of their Refer to the learning objectives above. Complete the questions below. electrical input into light? Go to the self-report form on page 230. Follow the reporting instruc- a. 6–7 percent tions, answer the test questions and submit the form. Or use the Contin- b. 3 percent uing Education self-report form on Record’s website — archrecord.con- c. 19 percent struction.com — to receive one AIA/CES Learning Unit including one d. 28 percent hour of health safety welfare credit. 7. California officials say the potential exists to reduce lighting energy use QUESTIONS and peak demand in the state by up to what percentage by the year 2020? 1. Ambient light levels in the American workplace have declined to one- a. 15 percent third of 1970s levels. Today, ambient office lighting is likely to be in the b. 35 percent range of: c. 50 percent a. 25–45 footcandles. d. 375 percent b. 35–55 footcandles 8. If a fixture gives 2000 candelas in the downwards direction, and if we c. 35–55 lux mount that fixture in a 10-ft high ceiling, the illuminance from that d. 135–145 footcandles fixture will be how many footcandles at the floor directly below the fixture? 2. Those 50 years of age and older require what percentage more contrast a. 20 than do those in their 20s? b. 50 a. 125 percent c. 100 b. 50 percent d. 200 c. 350 percent 9. High-frequency electronic ballasts can increase the efficiency of d. 250 percent fluorescent lighting systems by what percentage over systems using 3. A 13-watt compact fluorescent task light will produce the same light magnetic ballasts? output as a 75-watt incandescent light. a. 9 percent a. true b. 14 percent b. false c. 29 percent 4. Lamps that are high to very high in color temperature (5,000k to d. 83 percent 7,500k) provide improved visual acuity compared to lower-color 10. Which has the greater light output: a 26-watt fluorescent lamp or a 100- temperature lamps (typically 3,500k) at the same light level. watt incandescent lamp? a. true a. a 26-watt fluorescent b. false b. a 100-watt incandescent

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FREQUENTLY ASKED QUESTIONS What is task lighting and why should we use it? What Color Rendering Index (CRI) should task light bulbs have? Task lighting provides the correct amount of light for the task being per- CRI is a method for describing the effect of a light source on the color appear- formed. Viewing a computer monitor or walking down the aisle requires ance of objects being illuminated. A CRI of 100 represents the reference condi- far less light than does reading a typewritten page, making it neither effec- tion of daylight (and thus the maximum CRI possible). In general, low CRI tive nor efficient to light the entire environment at the same level. When illumination may render some colors unnatural and lamps with a CRI under utilizing task lighting, the general lighting level in the facility can be low- 60 should not be used. It has been proven that at a certain point, the higher the ered to a level appropriate for monitor viewing, thus creating a softer, CRI, the lower the illuminance. A CRI in the 80s is good for all general tasks. more pleasant atmosphere and saving energy. Work surfaces are supple- I don’t like the light given off by fluorescent bulbs. Can they be made mented with task lighting to give workers total control over where and to give off a warmer light like incandescents? how much light they need for other tasks, such as reading a document. Yes, compact fluorescent bulbs are available in color temperatures ranging Why choose a compact fluorescent task light? from 2700K for warmer light to approximately 4100K for cooler sources like Compact fluorescent bulbs use less energy than incandescents (about one daylight fluorescent. fourth), output more light (approximately three times as much) and last I’ve heard that “full-spectrum lighting” is better than regular fluores- up to 10 times longer. Compact fluorescent bulbs are also much cooler in cent lighting. Is that true? operation than regular incandescent bulbs or halogen bulbs and are, there- The short answer is “no.”Any bulb with a CRI of over 90 is considered a full- by, safer and more comfortable to work near. spectrum bulb. Full-spectrum lighting is neither better nor worse than any How does a mini-fluorescent bulb differ from earlier generation fluores- other lamp type. Claims made for its beneficial effects go beyond what scientif- cents? As I understand it, mini-fluorescents were used in earlier genera- ic literature will support. tion task lights but fell out of favor when halogen bulbs were introduced. What is the difference between a magnetic and electronic ballast? First generation “mini” or “compact” fluorescent bulbs suffered from flick- Magnetic ballasts use coiled wire to create a magnetic field that transforms voltage. er, low light and an audible hum. These objectionable characteristics have A magnetic ballast does not change the frequency of the power to the lamp—it been eliminated in the current generation of mini-fluorescents and accom- remains the same as the input power, which in the U.S. is 60 Hz. Electronic ballasts panying ballasts. Today’s fluorescents are long-lasting and have a light out- use solid-state components to transform voltage, while also changing the frequency put as good as, if not better than, halogen or regular incandescent bulbs. from 60 Hz to 20,000 Hz or higher, depending on the ballast. Because electronic ballasts don’t use coils or electromagnetic fields, they can function more efficiently and cooler than magnetic ballasts. However, they are also more prone to failure. I

GLOSSARY Color Rendering Index (CRI): method for describing the effect of a light source on the color appearance of objects being illuminated. A CRI of 100 represents the reference condition of daylight (and thus the maximum CRI possible). In general, low CRI illumination may render some colors unnatural.

Footcandle: unit of measurement indicating how much illumination reaches a surface, equal to one lumen striking an area of one square foot.

Ballast: a device used with an electric-discharge lamp to obtain the necessary circuit conditions (voltage, current and wave form) for starting and operating. A ballast can be electronic or magnetic.

Lumen: the unit of measurement used to describe the output from a light.

Lux: unit of illumination closely equivalent to 1/10 of one footcandle.

Two-Component Lighting: combination of indirect general (ambient) light and task lighting.

ABOUT HUMANSCALE

Humanscale designs and manufactures ergonomic products for a more comfortable workplace. From the Freedom chair to the Diffrient Light – each product is designed to improve the health, efficiency and quality of work life. Humanscale’s seating, monitor arms, lighting, keyboard supports and other ergonomic accessories follow the belief that if a design solves a functional problem as simply and elegantly as possible, the resulting form will be honest and timeless. Headquartered in New York City, with global distribution, Humanscale remains the leader in ergonomic design. For more information contact Customer Service at 800-400-0625; or visit the website at www.humanscale.com.

(800) 400-0625 www.humanscale.com

Bright Ideas—Office Lighting 101.

Architectural Record Version: 01Filename: 09/04Humanscale(reprint).qxd Black Cyan Magenta Yellow Issue Date: September 2004 Writer/Designer: Kenneth Kaiser Page No: 192a Last Revision: xx RHP 5 25 50 75 95

AIA/ARCHITECTURAL RECORD CONTINUING EDUCATION

Program title: “Bright Ideas —Office Lighting 101,” sponsored by Humanscale, (09/04, page 192a) 094SPONM

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Reprinted with permission from Architectural Record, September 2004

Bright Ideas—Office Lighting 101.

Architectural Record Version: 01Filename:Architectural09/0 Record4Humanscale(r Version:eprint).qxd01 Black Cyan Cyan MagentaMagentaYellowYellow Issue Date: September 2004 WIssueriter/Designer: Date: xx Kenneth Kaiser Page No: 192a LaPagest Revision: No: xx xx RHPLHP 5 25 50 75 95