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Are Incandescents Obsolete?
Just as incandescent lamps displaced gas lighting and kerosene lamps, it may finally be time for incandescents to take their place as museum artifacts. The European Union, China and Australia are considering banning incandescents, as are some large states and provinces, including California and Ontario. The replacement: screw-in compact fluorescent lamps (CFLs).
After two decades of gradual improvement, CFLs have finally begun to catch on as both a viable way to cut power bills and a legitimate response to concerns over global warming. They provide the same light but involve only a fraction (one quarter to one third) of the wattage and power plant emissions caused by incandescents. With lifetimes five to 10 times longer than incandescents, maintenance is also greatly reduced.
CFLs have come a long way since the ‘90s, when many facilities had their first — sometimes unpleasant — experience with them. Early units used large and heavy magnetic ballasts. Today, nearly all screw-in units have small built-in electronic ballasts that are light, quiet (no hum or hiss), start immediately (no more irritating flicker), and have acceptable or good power quality.
Units now fit easily into many existing incandescent fixtures and have light outputs equivalent to up to a 320-watt incandescent. Prices have dropped (six packs of 15-watt units are available at some retail outlets for under $12), color quality is much better and several color temperature choices are available. CFL units are also available with the mini-candelabra bases often found in decorative fixtures, such as sconces and chandeliers. Some have the same pseudo-flame shape as the bare incandescents popular in such lighting.
While screw-in CFLs are an easy retrofit, they may not always be the best CFL choice. Plug-in CFLs are equipped with two or four pins instead of screw bases, and have no built-in ballast, instead using ballasts built into fixtures. Pin-based sockets, specific to each lamp wattage, are also part of the fixture. This option has several advantages: Lamps may be cheaper, energy savings may be greater and there’s no way for an incandescent to be used (a common phenomenon called “snapback”).
The downsides? It isn’t possible to change lamp wattages should a higher or lower light level later be desired, and a ballast failure often requires replacing the fixture. Unlike replacement ballasts for linear fluorescents, which are readily available through many electrical suppliers, replacement CFL ballasts are still generally a specialty item.
Lighting upgrades in commercial spaces typically focus on altering linear fluorescent fixtures because they often account for 95 percent of lighting and are amenable to simple changes, such as lamp and ballast replacements. Often untouched, however, are incandescent fixtures that, despite their smaller number, may account for 10 percent or more of total lighting wattage. While upgrades are sometimes more difficult, such efforts typically yield significant bang for the upgrade buck.
Some incandescent-to-CFL conversions may involve nothing more than lamp replacement, but others, like sconces, chandeliers, spotlights, decorative or historical fixtures may present significant challenges due to lamp type, placement, light distribution and other factors. Such upgrades may require aesthetic sensitivity often lacking in electrical contractors.
A Few Tricks of the Upgrade Trade
One way to ensure good results is to use an upgrade specification written or reviewed by an experienced and preferably certified lighting specialist with background in changing such fixtures. Such personnel are aware of ways to alter existing fixtures without violating their UL listing to accommodate CFLs, or to replace them with nearly identical models designed to accept CFLs.
For example, to get a surface-mounted incandescent fixture to accept CFLs, contractors may replace its shade (e.g., globe) with a larger or different shaped unit, or use socket extenders to better locate the CFL inside the fixture. Various adapters, mini-candelabra to medium base, for example, also are available to make such adjustments.
Raising color temperature from the typical incandescent 2,700 K to 3,000 K to 3,500 or 4,100 K (somewhat more blue) may also yield a brighter and possibly better-looking space. Tests performed by lighting scientists have shown that higher color temperatures improve visibility, making occupants think light levels are roughly 10 to 20 percent higher than measured.
Another option used by some lighting professionals takes advantage of the low heat output of CFLs to raise light levels in spaces primarily illuminated by incandescents. Typical incandescent fixtures are designed to withstand the high heat output of lamps up to a defined wattage, but may be damaged if higher wattage lamps are used, thus limiting the ability to boost the fixture’s output. On the other hand, replacing a 60-watt incandescent with a 20-watt CFL, which roughly matches the output of a 75-watt incandescent, yields a room that is roughly 25 percent brighter while still saving power and not burning up the fixture. This trick works especially well in multilamp decorative fixtures where use of higher wattage incandescents could quickly damage the fixture or an adjacent surface.
Where resistance to changing to CFLs may occur, usually due to pre-conceived notions based on poor quality fluorescent lighting in past years, a bit of cleverness helps. Start by concealing the change. Do it during off hours, and be sure to upgrade all fixtures with the same lamp color. When all incandescents have been changed out in a space, differences between them and CFLs are not visible. Where bare bulbs are being replaced, use CFLs that mimic the look of those they are replacing. Be sure to replace any missing shades: where lamps are enclosed, and no one sees the lamps being switched, few if any will notice the change.
During the initial conversion, mimic the existing light level and color temperatures. Unless existing light levels are already too low, choose CFLs based on lumen output, not some wattage rule-of-thumb. Maintaining the illumination level at tasks or on wall surfaces will avoid calling attention to the change. While higher color temperatures typically result in better visibility, make the initial conversion using 2,700 K lamps that most closely match incandescents. When it comes time to group relamp, consider raising color temperature, but first do a test to be sure that furnishings still look good.
Even historical and decorative light fixtures like small sconces or chandeliers are no longer immune to upgrading. Some lamp manufacturers offer mini-candelabra-based CFLs in the flame incandescent shape. Experience shows that, after a week or so of adaptation, the new lighting becomes the accepted norm.
Where Screw-in CFLs May Not Make Sense
Track lighting, with its need to focus light output onto a product or surface, may not be a good choice for CFL conversion. The reflectors built into such fixtures depend on the source being very small (e.g., a glowing filament), but CFLs emit their light from multiple tubular surfaces, making it very difficult to concentrate. While a few reflector style CFLs exist, they do not produce the tight beams found in many R or AR style spot lamps. However, other energy-efficient light sources may do so.
A similar issue may arise when a CFL is inserted into a standard incandescent downlight often called a “high hat.” Instead of producing a well-defined “pool” of light on the floor, the fixture with a CFL will probably produce a gradually thinning glow that merges with others from nearby fixtures. If lighting patterns cast on surfaces are important, such as in an artistic or architectural environment, a different light source may be required.
Fluorescent lighting of all types is sensitive to ambient temperature, with most light being emitted within a narrow range. Output drops when the lamp becomes much colder or hotter. As a result, placing CFLs in open outdoor fixtures in cold climates may yield disappointing results. In some cases, they may not start, or ever reach their rated output. While special low-temperature lamps are available, they are more expensive and choices are limited.
|For information on Department of Energy tests of LED downlights
Request the free detailed lab test results from the DOE study
Motion sensors were the bane of early model CFLs, causing them to burn out in months instead of years. Magnetically ballasted units used a preheat starting process that wore down cathodes each time lamps were started. Motion sensors, when set for short cycling periods — for example, time after occupancy before shutoff — tend to start lamps many more times than occurs with manual light switches. While electronically ballasted CFLs are more resistant to frequent starting, their lifetime may also suffer, unless cycle times are raised to 15 or 20 minutes.
In some board rooms, or other high-end locations having highly polished wood surfaces and expensive furnishings, conversion to CFLs may create aesthetic problems. If the materials and wood stains were chosen under incandescent lighting, even 2,700 K CFLs may cause such surfaces to look flatter due to their lower output of red light, relative to incandescents that are rich in that color. Test first in one location before changing all fixtures. When the space is next remodeled, however, request that new furnishings be chosen under high-quality fluorescent lighting because new energy codes may require that light source.
Some museums and art galleries have resisted using CFLs due to their ultraviolet (UV) output, which may damage sensitive items. All fluorescent lighting emits more UV per unit of visible light than standard incandescents, but controlling it may be easier with CFLs due to their low heat output. Acrylic plastic lenses may cut UV by 80 percent or more and specialty glass filters are available that cut it by 95 percent. Such filtration has resulted in lower UV from CFLs than was emitted by the prior bare incandescents.
While several models of dimmable screw-in CFLs are available, none emits less than 10 percent of peak output. In some presentation spaces, like conference rooms, theaters and auditoriums, a lower minimum level may be needed. Plug-in CFL fixtures, using built-in dimmable electronic ballasts, will do the trick but are expensive.
|For a general wrap-up of CFLs
Back in the days when electricity was cheap, some buildings were designed to use the heat output of their lights as a winter fuel source. Where incandescents made up much of the lighting in a space, a drop of 65 percent in lighting wattage, which is common after CFL conversion, could create a climate control problem. Where electric resistance baseboards exist, extra power may be consumed during winter that matches the expected savings from the higher efficiency lighting. In such cases, think through the implications of an upgrade before any installation work occurs.
Where tightly focused light output is important, ceramic metal halide fixtures may offer a good solution. While a bit pricey, they provide tight beams, good color and color rendering that rivals incandescent spots. Ceramic metal halide fixtures are becoming common in many retail outlets as the track lights of choice because, like CFLs, they use only a fraction of the power, emit much less heat per unit of light and last many times longer than incandescents.
Many lighting applications that use small incandescents — decorative, instrument and case lighting, for example — are now being better served by light emitting diode (LED) lamps or metal halides whose output is “piped” through fiber optic cables. Even incandescent Christmas lights are being supplanted by LEDs. But be careful with some recently offered LED downlights: DOE tests yielded disappointing results.
Lindsay Audin is president of EnergyWiz, an energy consulting firm based in Croton, N.Y. He is a contributing editor for Building Operating Management.