It isn't socket science, but there are a few things you'll need to know before buying any energy-saving bulb. For starters, Energy Star-qualified bulbs meet high standards for brightness, color, and energy use, and the mercury content is capped in compact fluorescent lightbulbs. After 3,000 hours of testing, we found which CFLs and light-emitting diode bulbs, or LEDs, perform the best.
Before you shop visit www.dsireusa.org/incentives or www.energystar.gov to find utility rebates, and search online for manufacturer rebates. Check store displays of lit bulbs to get a feel for their light quality. Whatever you choose, buy just a few and try them out. And keep in mind the price of LEDs will continue to drop over the next few years. Also be sure to:
Consider the fixture
When replacing a bulb, choose a new one that's the same size or smaller to be sure it fits the fixture. Dimmers require dimmable bulbs and lights used outdoors must be designed for exterior use. Our Ratings indicate manufacturer-recommended uses; also check the bulb package for details.
Look at lumens
Select bulbs that provide the desired brightness at the lowest wattage (watts indicate energy use). Brightness is measured in lumens. When buying CFLs and LEDs known as A-type for their bulbous shape--the kind used in lamps and other fixtures--look for at least 450 lumens if you're replacing a 40-watt bulb; 800 lumens or more for a 60-watt bulb; at least 1,100 lumens for a 75-watt bulb; and 1,600 lumens or higher when replacing a 100-watt bulb. For R30 floodlights, look for at least 10 times the watts of the bulb you're replacing, 650 lumens to replace a 65-watt bulb, for example.
Choose a color
Warm lighting is flattering and used in most home applications, so the Kelvin temperature is in the lower end of the range. Standard incandescent bulbs produce a warm yellowish light and have a color temperature of about 2700 Kelvin (K). If you like that warm color, look for CFLs and LEDs with about 2700K. At 3000K, the light is whiter and comparable to a halogen's. For a cool, bright white light, look for bulbs in the 3500K to 4100K. And 5000K to 6500K bulbs mimic natural light or daylight.
The Color Rendering Index, or CRI, tells you how accurately colors appear under the bulb's light. The CRI ranges from 0 to 100 with daytime sunlight at 100 and incandescent bulbs right around that. A CRI of at least 80 is generally recommended for interior lights, and differences of fewer than five points are insignificant. To compare bulbs, look at the CRI of bulbs with the same Kelvin temperature.
Copyright © 2006-2012 Consumers Union of U.S., Inc. No reproduction, in whole or in part, without written permission.