Incandescent light bulbs are extraordinarily inefficient. Of the energy they consume, just 10% emits as visible light and a whopping 90% emits as waste heat. According to ENERGY STAR®, if every household in the United States changed one incandescent light bulb for an ENERGY STAR rated bulb, the annual energy cost savings would approach $600 million and greenhouse gas emissions would drop by 9 billion pounds. This would be like taking 800,000 cars off the road.
ENERGY STAR-rated light bulbs save energy by using 75% less energy and by emitting 75% less heat, thus reducing home cooling costs. These bulbs include compact fluorescents (CFLs) and light emitting diodes (LEDs). When buying, look for the ENERGY STAR logo.
CFLs come in various shapes and fit most incandescent bulb lighting fixtures. CFL light color varies; for the most incandescent-looking light, choose 2700-3000K CFLs. CFLs last six times longer than incandescent bulbs, but have drawbacks—they are fragile, they take as much as a minute to come to full brightness, and they contain mercury (a heavy metal and toxic pollutant), classifying them as household hazardous waste. Spent CFLs must be recycled; see Earth 911 for local CFL recycling information.
Mercury-free LED bulbs last 22 or more years in a typical home, are more durable, come on instantly, and are more energy efficient than CFLs, but they are also cost more up-front that CFLs. A new Phillips 60 watt replacement bulb arriving in stores in 2012 is most like an incandescent bulb in brightness and color, lasts 25,000 hours and uses 9.7 watts to produce the 60-watt equivalent luminosity.
Dimmable CFLs have limitations: they are more expensive, have shorter lifespans, require special dimming switches, and multiple bulbs on the same dimming switch may not have differing brightness levels. Dimmable LEDs are also a bit more expensive but do not share the limitations of dimmable CFLs.
For more information:
on CFLs and LEDs, see http://eartheasy.com/live_energyeff_lighting.htm
on ENERGY STAR, see http://www.energystar.gov/