Note: The lighting community generally uses the term "lamp" to mean the actual source of light--what the public usually calls the "light bulb."  In this chapter, we use "lamp" to refer to the light source.

Most buildings require several types of lighting, for example: ambient lighting for basic illumination of the space; task lighting, which enables users to control additional light they may require at their work space; architectural lighting to convey a particular mood or feeling (e.g., in a corridor or lobby); and display lighting to highlight particular features in the space (e.g., merchandise in a store, a painting in an office or museum, or a chalkboard in a schoolroom).  These webpages provide some guidelines for making efficient choices for a range of lighting applications. However, to maximize the efficiency of the lighting system, first consider the primary use of the space, the extent to which the lighting system can take advantage of natural lighting, and the degree to which task lighting can supplant general illumination. If possible, employ a professional lighting designer or supplier whose design background and attention to efficiency are established to assist you in creating an efficient lighting system. 

• Ambient Lighting
• Task Lighting
• Architectural Lighting
• Retail Display Lighting
• Large Area Lighting
• Utility and Service Areas
• Exits

Ambient lighting provides general illumination of a space. General lighting designs were originally intended to serve the primary lighting needs for office typing pools. With the advent of modular office furniture, general lighting designs were no longer practical. The furniture shadowed the light, and new equipment (computers) imposed new demands. In response, lighting designers shifted toward a system that combines lower ambient light levels with task lighting. As a result, instead of providing 100 percent of light for the space, it is now recommended that ambient lighting be designed to provide about 30 percent of the lighting needs, with the rest of work-oriented lighting provided by natural light and task lighting. 

In general, nearly optimal results can be achieved by using new 700-series "super" (or "premium") T8 (see table below for comparison), or T5  fluorescent lamps with electronic ballasts for low-ceilinged spaces and HID or high-intensity T5 lamps for spaces with higher ceilings.

• Super T8s are high-lumen, extended-life replacements for standard 700-series F32T8 lamps and standard electronic ballasts. (Keep in mind that electronic ballasts are available in several varieties such as normal, high, or reduced light output, dimming or non-dimming, etc.)  When super T8s are used with new reduced-power electronic ballasts, system wattage can drop by 15 to 20 percent relative to conventional T8s and electronic ballasts. In older systems using T12 lamps and magnetic ballasts, the savings are even greater. As an added benefit, improved phosphors reduce lumen depreciation so super T8s continue to deliver more lumens per watt over their lifetime (see comparison table below). Their higher lumens and improved lumen maintenance (i.e., 88 to 92 percent end-of-life lumens) allow super T8 lamps to provide the same light levels with a reduced-power ballast. New high-efficiency ballasts are available with ballast factors less than 0.78. Super T8s present an additional opportunity for energy savings in delamping retrofits (one super T8 replaces two standard lamps) when used with high-power ballasts (i.e., 1.00 to 1.20 ballast factor, also known as “max output” ballasts), yielding energy savings of up to 30 percent. 
• Commercial HID lighting systems are used in a number of facility types, including offices, schools, stores, airports, and shopping malls. While there are many types of HID fixtures, high-bay and low-bay area and aisle luminaires are among the most common. HID luminaires are generally energy efficient if metal halide or high-pressure sodium lamps are used. Mercury vapor lamps should be avoided. Remember that high-pressure sodium lamps are not suited for spaces with any type of detailed task work; retail sales, industrial assembly, and similar work areas should have metal halide or fluorescent lighting. Newer metal halide lamp and ballast technologies (e.g., pulse-start lamps and new electronic HID ballasts) offer energy-saving options that apply especially to 250 to 400 watt sizes. In particular, 400 watt metal halide lamps can be operated from "linear reactor" ballasts at 277 volts and save 8 percent of normal energy use. Also consider lower-wattage lamps for 250 and 400 watt sockets when light levels are not critical. 

• High-intensity fluorescent lighting systems are an energy-efficient alternative to high-intensity discharge lamps in many medium- and high-bay applications including retail outlets, industrial facilities, and warehouse and storage space. New high-intensity fluorescent lighting systems incorporate high-output linear T5 (T5HO) fluorescent lamps with high-efficacy fixtures to maximize light output in the space. Each of the system components confers advantages over traditional HID fixtures. Advantages include: lower energy consumption; lower lumen depreciation over the lifetime of the lamp; better dimming options; faster start-up and restrike (virtually “instant-on” capability); better color rendition; higher pupil lumens ratings (translating into improved worker productivity and performance); and less glare (given fixture design and the more diffuse nature of the fluorescent light source) [Rogers, J. and I. Krepchin. 2000. New High-Intensity Fluorescent Lights Outshine their HID Competitors. ER-00-1. Boulder, Colo.: E Source]. Many lighting designers recommend a mixture of high-efficiency HID lamps (e.g., pulse-start metal halides with electronic ballasts) and high-intensity fluorescents to maximize cost-effective energy savings. [Walerczyk, S. and B. Liebel. 2002. "Cutting Edge Retrofitting and Relighting". Seminar presentation at Lightfair International 2002, San Francisco, Calif., June 2.]. Under similar operating conditions, high-intensity fluorescent replacements yield 50 percent electricity savings over standard metal halide HID lamps. For a typical application, this translates to annual energy savings of more than 900 kWh per fixture. The use of dimming or on/off controls, which are impractical with most HID systems, can increase savings substantially. The first high-intensity fluorescent systems suitable for medium- and high-bay applications were introduced in 1996. Since that time, the number of fixture manufacturers has grown to more than a dozen, prices have dropped dramatically, and the number of contractors experienced with installation of the systems has grown.

Comparison of Standard T8 and "Super" T8 Systems
Lamp/Ballast	Initial Lumens	Ballast Factor	Lamp Life	System Wattage
Standard F32T8  with electronic ballast	2,850	0.88	20,000	1-lamp fixture =  30 W 2-lamp fixture =  58 W 3-lamp fixture =  87 W 4-lamp fixture = 114 W
Super F32T8 with reduced-power electronic ballast	3,200	0.78	24,000	1-lamp fixture =  25 W 2-lamp fixture =  48 W 3-lamp fixture =  73 W 4-lamp fixture =  96 W

Source: Cutting Edge Retrofitting and Relighting.

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Luminaires for Ambient Lighting

Although there are thousands of different fluorescent luminaires, each having subtle variations, two types are common choices for commercial and light industrial lighting: lensed and parabolic troffers. Most office buildings and many retail stores employ acoustical tile suspended ceilings; troffers are simple steel-trough fixtures with a lensed face (in the case of lensed troffers) or louver face (in the case of parabolic troffers) that fit in the space of a single tile. Troffers are placed in a pattern to create general lighting throughout the room. Typically, a 2-lamp recessed troffer every 64 square feet (8-foot by 8-foot grid) or a 3-lamp recessed troffer every 80 square feet (8-foot by 10-foot grid) provides 50 to 60 footcandles on average in most open office and private office spaces. Note that new guidelines from the Illuminating Engineering Society of North America (IESNA) set the recommended level of ambient lighting at 20 to 30 footcandles augmented by task lighting for typical office applications with desktop computers. This can be achieved even with 1-lamp fixtures. [Illuminating Engineering Society of North America. 2000. IESNA Lighting Handbook. 9th Edition. New York, N.Y.: Illuminating Engineering Society of North America]. 

Lensed troffers constitute more than 50 percent of the market in commercial fluorescent lighting. In general, they offer the lowest installed cost per foot-candle, and choices of lenses, lamps, and ballasts provide some variety. Materials for lensed troffers cost about two-thirds that for parabolic troffers. Parabolic troffers, which constitute 25 percent of the commercial fluorescent lighting market, use polished aluminum louvers rather than lenses to shield the lamps from view. The louvers have a parabolic shape developed to reduce glare from direct lighting systems in open office areas. As a result, however, parabolic troffers are somewhat less efficient than lensed troffers (i.e., 55 to 70 percent versus 60 to 80 percent). Recently, versions of parabolics have been optimized for use in computer workspaces, an application for which lensed troffers are not a good choice since the bright lenses produce glare that can reflect on computer screens.

For new troffer systems (except in computer-intensive workspaces), we recommend the following:

• Use 1-lamp or 2-lamp 2-foot by 4-foot troffers in most situations. Always specify T5 or super T8 lamps with appropriate electronic ballasts. Lenses and louvers should generally be the industry standard. One-lamp fixtures can also be used with super T8s and high-output electronic ballasts.  
• For 2-foot by 2-foot luminaires, consider three 2-foot T5 or T8 lamps, instead of U-bent or twin tube lamps, since they are more efficient, cost less, and are more easily stored.
• For new lensed troffers, there is little need for specular silver or aluminum reflectors. They increase efficiency by only a few percent and the cost is generally not warranted.
• For new parabolics, avoid silver or polished reflectors as they create glare.
• Where 2-lamp fixtures are used, "tandem-wire" adjacent fixtures so the fixtures can be controlled by one 4-lamp ballast, reducing energy use by 9 percent. Even with the extra labor costs for tandem wiring, a 4-lamp ballast costs about the same as two 2-lamp ballasts. Where 1-lamp fixtures are used, tandem wire with 2-lamp or even 4-lamp ballasts.

For existing troffer systems (except in computer-intensive workspaces), we recommend the following:

• In most cases, delamp 4-lamp luminaires to either 2 or 3 lamps. Silver or polished aluminum reflectors should be installed in most older lensed troffers, and white painted reflectors should be installed in older parabolic troffers. Consider 1-lamp fixtures fitted with super T8s and high-output electronic ballasts.
• Convert T12 lighting systems to super T8 lamps with appropriate electronic ballasts.
• Install new lenses in lensed troffers if existing lenses are more than seven or eight years old.

Special considerations for computer-intensive workspaces include the following:

• Most lensed troffers are not suited for computer workspace; consider using a parabolic louver conversion kit or reducing general lighting and adding task lighting.
• If the lensed luminaires are retained, remove the lens and install a specular (mirror-like) reflector.
• In selecting new luminaires, consider whether a standard parabolic or special video display terminal (VDT) parabolic troffer is best. VDT luminaires are distinctive in that they have specular louvers with a special shape. VDT luminaires are more expensive and less efficient, so choose them only for work areas with intensive computer work.

Downlights, often called "cans" or "highhats," are used for general illumination in many residential and commercial applications, especially in lobbies, halls, corridors, stores, and other finished spaces. Downlights can be equipped with incandescent, halogen, low voltage, compact fluorescent, or HID lamps. Compact fluorescent and HID lamps should generally be selected using a rule of thumb of 1 watt for every 3 watts of incandescent or halogen that would normally be used.

• For most applications, consider vertical lamp and dual horizontal lamp compact fluorescent downlights.
• For applications requiring high-wattage incandescent or halogen lamps, consider metal halide downlights, especially with the new high color quality ceramic metal halide lamps.
• If the above options are not appropriate, consider retrofitting existing cans to use CFLs. Retrofit kits generally work better and save money over the long run, but screw-in retrofits provide lower first cost and often are acceptable in performance and aesthetics, particularly in low-ceilinged spaces.
• Failing all of the above, consider replacing incandescent reflector lamps with lower wattage halogen or energy-saving incandescent lamps.

Task Lighting

Shifting from older general lighting systems to an approach based on lower ambient light levels with a task lighting complement introduces energy savings opportunities by allowing some degree of occupant control over lighting levels. Research shows that individual preferences for lighting levels vary widely and that allowing individuals some control over their own lighting not only increases user satisfaction and productivity, it also results in measurable energy savings. [Boyce, P., N. Eklund, and S. Simpson. 2000. "Individual Lighting Control: Task Performance, Mood and Illuminance." Journal of the Illuminating Engineering Society 29(1): 131–142]. Task lighting also makes it easier to adapt the lighting in a space as end-uses or occupants change. Many types and configurations of task lighting are available to meet user preferences and needs, including under-cabinet lights, table lamps, and floor lamps. Task lighting typically uses a fluorescent or compact fluorescent source. Improvements in CFL technology have made dimmable lamps increasingly common and some specialized fixtures are taking advantage of these developments, such as CFL torchiere lamps and the award-winning “Berkeley Lamp." For applications where linear fluorescent lamps are used (such as under-cabinet lamps), use T5 or T8s with appropriate electronic ballasts.

Architectural Lighting

CFLs or metal halide lamps for downlighting, wallwashing, wall sconces, and pendant fixtures can be used for architectural effects; larger fluorescent lamps can also be used for wallwashing. Advancements in metal halide technology have produced ceramic metal halide lamps with improved color rendering characteristics. The use of ceramic arc tubes in metal halide lamps provides the warm tones desired in retail applications and the concentrated beams required for accent lighting in retail and other architectural applications. Furthermore, these lamps represent an attractive alternative to the halogen PAR lamps commonly used in these applications because they have a much longer life and use just half of the energy. See the table below. All major lamp manufacturers offer ceramic metal halide spot lamps.

Comparison of Ceramic Metal Halide and Halogen PAR Lamps
Lamp Type	Watts	Initial Lumens	Avg. Life (hours)
Halogen PAR	100	1,400	2,000
Halogen-IR PAR	100	2,070	3,000
Ceramic Metal Halide	39	2,200-2,400	9,000-10,000

Sources: General Electric Lighting. 2002. www.gelighting.com. Cleveland, Ohio: GE Lighting Institute; Philips Lighting. 2002. www.lighting.philips.com/nam. Somerset, N.J.: Philips Lighting North America.

Retail Display Lighting

Track lights are the most common display lighting systems. Track lighting consists of electrified track to which are attached lampholders, sometimes called track fixtures or "heads." Track was developed to offer flexibility for display lighting in stores and museums. It has become a popular way to incorporate display lighting in many building types. Unfortunately, track enables (and often encourages) the use of too much incandescent or halogen lighting. 

For retail display track lighting, use fluorescent lamps for washes and valances, and halogen infrared reflector lamps for spot-lighting and most display applications. Those especially conscious of energy might use metal halide or try newer ceramic metal halide lamps for display but HIR lamps are generally more cost-effective at current costs. Halogen lighting, especially HIR lamps, is standard equipment for modern retail lighting and, given the limitations of more efficient light sources, is generally a pretty good choice. To minimize energy consumption, as a rule, use HIR-type lamps for most track fixtures and low wattage (35-100) metal halide lamps for large displays like cars and produce bins.  Low wattage ceramic metal halide PAR lamps, especially the 35 watt PAR lamps with relatively small electronic ballasts, have made track-mounted energy-efficient display lighting possible.  Although the number of lamp and ballast products is small (and they are fairly expensive), expect technology improvements to result in increased number of products and decreased cost fairly quickly.

Note that low voltage lighting systems, mostly using mirrored reflector (MR) lamps, have become very popular for track installations. These systems are especially suited for precision display lighting in some specific situations, but low voltage lighting is inherently inefficient and should not be used for display lighting of larger objects. In general, track lighting should be limited to applications where it is needed -- retail stores, galleries, and museums. It should be avoided in offices and other buildings except for a few specific locations, since track encourages relatively high wattage consumption by relatively inefficient sources.

Large Area Lighting, Indoors and Out

Use metal halide lamps if color discrimination is important or high-pressure sodium lamps if not. Electrodeless lamps, which are becoming more available, are appropriate in outdoor applications and in hard-to-reach indoor and outdoor applications, such as in malls with high ceilings or for security lighting. Their primary disadvantage is that they are expensive, although they offer long life which, reduces replacement and maintenance costs.

Use fluorescent, CFLs, or HID lamps as appropriate. Where small utility or service areas are occupied intermittently, incandescent lamps or CFLs on timer switches are often the best choices; occupancy sensors are another option for all but mechanical rooms. HID lamps are not suitable for service areas in which the lights must come on quickly. T5 high- output lamps can be used in place of HID lamps, since they are totally dimmable and controllable, provide greater energy savings, and improved color characteristics, and they last longer. 

Exits

Source: Gilbert Industries, Inc.

Exit signs use a surprising amount of energy. In 2000, EPA and DOE estimated that exit signs cost American businesses more than $1 billion annually. Many exit signs employ incandescent lamps, typically consuming 30 to 40 watts per unit.  These lamps are designed principally for long life -- they generally last 20,000 to 40,000 hours -- but efficiency is compromised in the process. A typical exit sign of this type consumes more than 300 kWh of energy per year.

In the 1980s, many exit signs were retrofitted with CFLs to save energy. At this point, however, LED exit signs are rapidly becoming the new standard. A typical LED exit sign consumes less than 3 watts per face; LEDs have a very long life (at least 50,000 hours), which reduces maintenance costs and provides even illumination. Recent developments in green LEDs make both red and green signs available and cost effective. Existing incandescent exit signs can be replaced or retrofitted with LED adapters.

The ENERGY STAR label help facility managers easily identify energy-efficient exit signs. Qualifying exit signs must consume fewer than 5 watts per face, which effectively requires the use of LEDs and electroluminescent technology. ENERGY STAR is currently revisiting its specification and considering revisions that would allow photoluminescent and self-luminescent (requiring no power) exit signs to qualify under the program. ENERGY STAR maintains a list of qualifying products as well as a cost calculator for estimating how much you would save from converting to ENERGY STAR exit signs.