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Switching from incandescent bulbs to compact fluorescent lights (CFLs) will cut your dependence on energy and save you money. CFLs provide three to four times more energy savings over comparable incandescents. If every household in America switched to efficient bulbs in only one room, power plants would release one trillion pounds less CO2, the major greenhouse gas, into the atmosphere each year. Reduced consumer demand also translates into a 13.6 mg-per-bulb reduction in power-plant emissions of mercury, a nerve toxin that finds its way from the air into waterways and the fish we eat.

Although incandescents cost only 50 cents a bulb, their inefficiency and short lifespan mean their light doesn't come cheaply for the environment, our health or our wallets. CFLs may be higher in cost, but each lasts ten to fifteen times longer than an incandescent that provides the same light, at a quarter to a third the cost per hour. This saves you $25 to $60 per CFL. Look for bulbs certified efficient by Energy Star, a government program run by the Environmental Protection Agency and the Department of Energy.

To get the most natural light spectrum, ask for a CFL with a color-rendering index (CRI) in at least the 80s. (Sunlight has a CRI of 100; the higher the CRI, the more like sunlight the bulb's light is. Incandescents have CRIs in the 90s.) A medium, or Edison-type, spiral base means the bulb will fit your incandescent fixtures. Or you can buy pin-base CFL fixtures, which include most of the Energy Star-certified fixtures, themselves 75 percent more efficient than standard fixtures. Most CFLs are bigger than incandescents and don't fit all lamps; for small lamps, look for CFLs the size of conventional bulbs. Some CFL bulbs have three horseshoe-shaped fluorescent tubes that taper into a screw base; you can also find screw-based CFLs with spiral tubes, which provide better light distribution.