Artificial lighting consumes almost 15 percent of household electricity. The traditional incandescent bulb with screw base currently provides most household illumination. Use of new lighting technologies can reduce lighting energy use in homes by 50 to 75 percent.
What are the Options?
- Incandescent lighting has traditionally delivered about 85 percent of household illumination. Most familiar are the standard pear-shaped, screw-in “A”-type incandescent light bulbs. They produce a warm light and provide excellent color rendition. They have a low efficacy compared to all other lighting options (10 to 17 lumens per watt) and a short average operating life (750 to 2500 hours).
- Fluorescent lamps use 25 to 35 percent of the energy used by incandescent lamps to provide the same amount of illumination (efficacy of 30 to 110 lumens per watt) and last about 10 times longer (7,000 to 24,000 hours). Improvements in technology have resulted in fluorescent lamps with color temperature and color rendition that are comparable to incandescent lamps. Fluorescent lamps require a ballast to regulate operating current and provide a high start-up voltage. Fluorescent lighting can be dimmable, but requires a special CFL dimmer t
o do so.
Two general types of fluorescent lamps are available:
- The traditional tube-type fluorescent is usually identified as T12 or T8 (12/8 or 8/8 of an inch tube diameter, respectively) and is installed in a dedicated fixture with a built-in ballast.
- The newer compact fluorescent lamps (CFLs) and circulines have smaller diameters and are usually bent or twisted into compact shapes.
- The traditional tube-type fluorescent is usually identified as T12 or T8 (12/8 or 8/8 of an inch tube diameter, respectively) and is installed in a dedicated fixture with a built-in ballast.
What Should the Focus Be On?
Home designers and builders can reduce lighting energy use by selecting light fixtures and sources that use energy more efficiently, and by installing controls to reduce the amount of time lights are on.
- Maximize the use of daylighting.
- Install fluorescent light fixtures for all ceiling and wallmounted fixtures that will be on for more than 2 hours each day. These often include the fixtures in the kitchen and living room, and sometimes those in bathrooms, halls, bedrooms, and other higher-demand locations. Install dedicated compact fluorescent fixtures, rather than CFLs in incandescent fixtures, so that fluorescent bulbs continue to be used for the life of the house.
- Encourage occupants to use CFLs in portable lighting fixtures that are operated for more than 2 hours a day.
- Avoid using recessed lighting in a ceiling with an unconditioned space above it whenever possible. If it is necessary to use recessed devices, use only Underwriters Laboratory (UL) approved fixtures that are airtight, are IC (insulation contact) rated, and meet ASTM E283 requirements. Recessed lighting fixtures must be air tight to reduce leakage, which can affect a home's HERS rating.
("Effiecent Lighting Strategies". Energy Techinical Bulletin. Office of Building Technologies. Accessed 27 July 2009).