Feature Article - October 2002
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Conserve Your Energy

Bright ideas that are easy on the environment—and your budget

By Elisa Kronish

Lighten up
The Mauna Lani located in Hawaii is the largest
solar-powered resort in the world. Its solar electric
systems reduce operational costs as well as
contribute to Hawaii's sustainability and environmental
preservation by offsetting diesel combustion for
power generation.

Saving energy through lighting requires either reducing electricity or reducing the amount of time the lights are on. To reduce electricity, you can replace existing fluorescent lights with more energy-efficient models, which provide a lower wattage but approximately the same light output. Replace incandescent lights (regular old bulbs) that are on more than a few hours a day with compact fluorescent lights (CFLs). For your efforts, you'll see payback in about two years, Barrie says.

Compact fluorescent lights (CFLs) combine the efficiency of fluorescent with the convenience of incandescent. The technology has been around for nearly 20 years, but it has become more popular in the past decade because of advancements in fixtures that fit them. They have also improved in terms of the amount of light they produce, says Joe Rey-Barreau, former director of education at the American Lighting Association. Compact fluorescents are about four times more efficient than a standard incandescent light, meaning a 25-Watt CFL equals about a 100-Watt incandescent bulb.

CFLs also have a longer life than incandescent bulbs. A 100-Watt incandescent brightens a room for about 750 to 1,000 hours, while a CFL keeps going to an average of 10,000 hours.

"From the point of view of just efficiency and long-term maintenance, you really can't beat these little guys," Rey-Barreau says.

Until recent years, one of the technical problems with CFLs was their aversion to cold weather. When the temperature got below freezing, they often wouldn't work. Improvements now allow use of them down to about zero degrees Fahrenheit.

If you're really going for the top of the line, then you'd want to look into high intensity discharge lamps (HID), which are commonly used for outdoor and street lighting. In terms of efficacy in lighting—translated to lumens per Watt—these produce the most amount of light for the amount of energy consumed. Incandescents produce from 17 to 20 lumens per Watt, fluorescents 80 to 100, HIDs 80 to 140.

Covering 10,000 square feet of the hotel
roof area, the solar electric system atop
the Mauna Lani Bay Hotel lowers air
conditioning requirements and extends
roof life by protecting it from damaging
effects of the weather—all while
generating clean electricity.

For outdoor applications, such as lighting pathways or a field, Rey-Barreau says that HIDs are very useful. But make sure you choose the right type of HID. There are three: mercury, metal halide and high pressure sodium. The mercury HIDs have an efficacy rating of about 60 to 80 lumens per Watt, and they give off a greenish-blue tint.

"In an outdoor environment, they make plants look really cool," Rey-Barreau says.

Metal halide is really just an improved mercury bulb. It provides higher efficacy (about 80 to 100, sometimes higher) and a life span of up to 20,000 hours. Rey-Barreau says these are being used almost exclusively now in outdoor sports facilities and shopping malls.

The third type, high pressure sodium, is the most efficient commercially available light bulb, producing 120 to 140 lumens per Watt rating with a life span of at least 24,000 hours. But the yellowish-orange tint makes people look jaundiced, so these lights are mostly confined to highways.

It depends on the fixture as to whether you'll need to get a new one to fit your new light, but compact fluorescents come in a variety of shapes and sizes. About 70 percent of incandescent fixtures will handle a direct switch with a compact fluorescent.

For added savings, invest in motion detectors. If you're running an overnight camp, for instance, kids who stumble bleary-eyed into the bathroom at 2 a.m. might stumble out again without turning off the light. A motion-detector system could keep them in check by clicking off after a certain amount of time.

"But you want to put a long timer on the lights, so people aren't left in the dark," Barrie says. An average motion detector runs about $20 and can simply replace a regular switch.