One of the best and easiest things that households can do for the environment is to switch to Compact Fluorescent Light Bulbs (CFLs) instead of normal incandescent light bulbs. CFLs use up to 80 percent less electricity to produce the same amount of light. And although they cost a little bit more up front, on average CFLs last for 5 to 7 years — more than 10 times the life of an incandescent bulb. Once costs for purchase and energy are considered, it is estimated that a single CFL will save an average homeowner $30. CFLs do contain approximately 4 milligrams of mercury. However, CFLs actually prevent more than 7.5 mg of mercury from being produced by emissions from power generation.