From Consumer Reports…
For starters, choose Energy Star-rated bulbs. They meet high standards for brightness, color, and energy use, and the mercury content is capped in compact fluorescent lightbulbs. Additionally…
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.
Look at lumens.
Select bulbs that provide the desired brightness at the lowest wattage. 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 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. (Note that LED’s still don’t produce significantly more (if any) lumens per watt than CFL’s…)
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.
Eco Smart 60 Watt Soft White Cfl Light Bulbs 4 Pack $8.79 ($2.20 each)
- 14 watt actually used=60 watt equivalent
- 10,000 life in hours
- lasts 9 years warranty
- 900 light output in lumens
GE 13-Watt Energy SmartTM – 8 Pack $9.25 ($1.16 each)
- 825 lumens.
- Energy used, 13 watts.
- Life – 8000 hours
For comparison, a Philips 409904 Dimmable AmbientLED 12.5-Watt A19 Light Bulb costs $15.15 and puts out 800 lumens. Its luminous efficacy is no better than a CFL. It’s advantage is that it lasts longer (theoretically, though these lamps are still too new to verify their actual life…), uses no mercury and is dimmable.
Other sources include miniinthebox.com