Switch to compact fluorescent lightbulbs (CFLs)

Why: Less than 3 percent of the energy incandescent light bulbs use becomes visible light. CFLs cost a bit more, but use 50-80 percent less energy than regular bulbs, paying for themselves in about nine months. Replacing a single incandescent bulb with a CFL will keep 1,000 pounds of CO2 out of the atmosphere over the life of the bulb. (What about mercury?)

How: Begin by replacing the lights you most often use. There are many different types of CFLs designed to work with dimmable lights and other special lighting fixtures. Be sure to use the right kind of bulb to save the most energy possible. Check the package for the Kelvin rating — numbers below 3000 give off soft warm light, while higher Kelvin ratings give off a blue-white light, good for task lighting.