How to Buy Compact Fluorescent Light Bulbs

They use 75% less energy and can have a noticeable impact on your electric bill. They make the changing-lightbulb routine almost obsolete. Here, a few things to keep in mind when picking some up at your local hardware store. (For a slideshow on which CFL is right for your exact need — we tested over 75 of them — see "The Best Eco Light Bulbs.")

1. What wattage to get: The higher a bulb's wattage (which is a measure of how much energy it takes to power the bulb) the more light it will produce. A CFL requires about a quarter of the energy needed to produce the same amount of light as an incandescent; many manufacturers list the watt equivalents right on the packaging. In general, though, look for a CFL with a wattage that's about a quarter of the incandescent you typically use. So a CFL in the 15-watt range is a good replacement for a 60-watt incandescent.

2. How to tell what kind of light it produces: The packaging for most bulbs will list the color temperature in degrees Kelvin; the higher the temperature, the whiter the light will be. If you prefer warm, yellow-ish-white light, look for a bulb with a color temperature of about 2650 to 3200 degrees Kelvin. Anything over 4000K is considered "daylight" and produces a whiter, almost blue-tinged light, which is generally better for desk lighting and lighting to ready by.

3. How to dispose of it: CFL bulbs contain a small amount of mercury — about 2 to 6 milligrams per bulb, which is an amount that would fit on the tip of a ballpoint pen and is far less than the amount of mercury in other household items. For example, watch batteries contain about 25mg and thermometers anywhere from 500mg to 2 grams. The mercury poses no risk while the bulb is in use, but you still need to dispose of or recycle CFLs properly. Home Depot stores accept bulbs for recycling, and by the time your bulb burns out, Wal-Mart should have a program in place. Ikea stores also do take-backs for recycling CLF bulbs, or you can visit www.lamprecycle.org or http://www.epa.gov/bulbrecycling/ for information on how to properly dispose of bulbs in your area and what to do if one breaks in your home.