In the beginning, there was light, and that is how it should be. “Lighting design shouldn't be an afterthought,” says Kathy Presciano, a lighting specialist with GE Consumer & Industrial, and a former commercial interior designer. “It should be thought of right from the start: How do I want lighting to set off the space and incorporate with the architecture and finish materials?”

Now, with the recent passage by Congress and President Bush of an energy bill that is the death knell for the incandescent light bulb, there will be even more to think about when creating lighting designs.

EFFICIENCY RULES Under the new measure, from 2012 through 2014, all light bulbs must use 25% to 30% less energy than today's incandescent bulbs; by 2020, bulbs must be 70% more efficient. Halogens and compact fluorescent lights (CFLs) are two “green” lighting options.

Halogens are also incandescent and produce more light per unit of energy than standard bulbs, but still waste heat. CFLs — although they already meet the 70% efficiency standard, offer good light distribution, and are low maintenance — cost up to four times more than incandescent bulbs, contain mercury, and, according to some designers, give off harsher light.

However, since lighting can account for 20% of a homeowner's electricity bill, it would seem that consumers will pay more up front to gain savings over time. So selling clients on more efficient forms of lighting may be easier than selling them on other, higher-ticket green items.

As for the environmental impact of used CFLs — which have about a two-year life span — the amount of mercury in each bulb is “about as big as a pen point,” Presciano says. Critics point out, however, that over time those pen points add up. Better disposal methods should be available in the next few years. (For disposal information go to www.epa.gov/bulbrecycling or www.earth911.org.)

SETTING THE MOOD For designers, the issue is ambience or emotional impact. “Your home is your haven. You want to feel good and use the new technology because of how it makes a home feel,” says Phil Blosser, a lighting designer, electrician, and owner of Blosser Lighting in Harrisonburg, Va. He feels fluorescents make a home “cold and foreboding.”

But new technology has made fluorescents warmer, Presciano says, “with much higher color rendering; they make things look good.” Incandescent light and outdoor sunlight have been the benchmark for color rendering — or how good color looks on a scale of 0 to 100. An incandescent bulb has a rendering of 100. “All GE's CFLs have a color rendering of 80 or higher,” she says. And, recently, dimmable CFLs and other CFLs that work in three-way switches have also come on the market.

Blosser and others say dimmers can be used to realize energy savings. “Putting in an expensive incandescent bulb that is dimmable so you only have it full-bright when you need it will save the same amount of electricity,” he says, “and you haven't eviscerated emotion in the place you come home to rest in and rejuvenate.” He uses an MR-16 — a low-volt incandescent bulb — for accent lighting, and places low-volt recess lights over task and accent areas. For the next few years, at least, this will still be an option. But making lighting choices based on energy use is becoming increasingly important in lighting design.

For more information about bulb types and their environmental impact, go to www.gelighting.com or www.energystar.gov.