Steven Nadel, executive director of the American Council for an Energy-Efficient Economy in Washington, DC, said if all commercial buildings nationwide installed state-of-the-art energy-saving lighting systems, they could reduce lighting energy use by at least 40%.

"In office buildings, the typical fluorescent lighting fixture with four four-foot fluorescent tubes--referred to as lamps in the lighting trade--and two magnetic ballasts uses 160 to 180 watts of power. However, new fixtures with special thin-diameter lamps and electronic ballasts use about 115 watts," Nadel notes.

"In spaces that are overlit--and many are--further energy savings are possible by switching from four-lamp fixtures to three or even two-lamp fixtures. Special reflectors can be installed to optimize light distribution for the reduced number of lamps in each fixture. The energy use of a two-lamp fixture can be as low as 58 watts, a savings of up to 70%.

"In stores, most displays are lit by incandescent spotlights, typically using 150 watts apiece. Special halogen IR lamps reduce energy waste and burn more brightly, permitting a 60 watt halogen lamp to be substituted for a standard 150 watt spotlight--a savings of 60%. The halogen lamp costs more--about $8.50 versus $2.50--but typically lasts 50% longer and saves $20 in energy costs over its lifetime."

The National Electrical Manufacturers Association (NEMA) has other suggestions to improve interior lighting:

1. Increase luminous comfort by distributing light on walls and ceilings;
2. Specify a Color Rendering Index (CRI) rating of 80 when color rendering is an important issue in the application, along with "white" light sources between 3000K and 4100K in color temperature;
3. Consider lower and/or translucent partitions in open plan offices;
4. Choose an 80%-plus reflectance for ceiling finishes and a 70%-plus reflectance for walls and vertical partitions. For indirect lighting and daylighting, a 90% ceiling reflectance is preferred;.
5. Utilize lighting systems--lamp-ballast combinations--that provide a minimum maintained efficacy of 90 lumens per watt;
6. Consider low-wattage ceramic metal halide lamps as an alternative to tungsten halogen lamps, and pulse-start metal halide instead of probe-start metal halide;
7. In some indirect lighting applications, it may be possible to use one T5HO lamp in place of two T8 lamps or otherwise increase the fixture spacing, reducing the number of fixtures and/or lamps used;
8. Use only electronic ballasts for linear fluorescent, compact fluorescent and metal halide lamps;
9. Use incandescent lamps as little as possible. Consider compact fluorescent or low-wattage metal halide instead when feasible;
10. Layer the lighting design where practical so that the general lighting system does not do the heavy lifting of task lighting;
11. Choose lamps with maximum service life to minimize maintenance;
12. Choose light fixtures that offer the highest optical efficiency. Fixture design is an often overlooked but powerful strategy for achieving energy efficiency. Select fixtures that get the light where it's needed at the great possible efficiency.