How CFLs Work
How CFLs Work | When Not to Use CFLs | Choosing the Right CFL
A compact fluorescent lamp (CFL) contains low-pressure mercury vapor that produces ultraviolet (UV) radiation when stimulated by an electrical charge. The inner surface of the lamp is coated with fluorescent phosphors that emit visible light when struck by the UV radiation. The flow of electricity to the mercury gas is controlled by a magnetic or, more commonly, an electronic ballast. Electronic ballasts enjoy several advantages over magnetic ballasts. They do not generate the undesirable flicker that characterizes magnetic ballasts when the lights are first turned on. Lamps powered by electronic ballasts last longer and are more efficient. Electronic ballasts are also lighter, facilitating their use in fixtures that would be too top-heavy with lamps powered by magnetic ballasts.
Relatively long linear or tube fluorescent lamps have been mass-produced since World War II, and have been used mostly in non-residential ceiling applications. Compact fluorescent lamps, first developed in the late 1970s, were designed specifically to replace incandescent bulbs. Available in many sizes and shapes, they can be used in most conventional fixtures designed for conventional light bulbs.
CFLs are so efficient that typically they save the consumer between 50 and 80% of the energy costs associated with the regular incandescent bulb they replace. In addition, the average CFL lasts more than ten times longer than its incandescent counterpart. The combined savings can often result in a net savings of approximately $50 from each CFL.
CFLs contain less than 4.0 milligrams (about 1/1000th of an ounce) of mercury to assist with starting. That amount of mercury is about the volume that would fill the size of the period at the end of this sentence, and is not dangerous in the home. Because coal-fired power plants release mercury in their emissions, the use of energy-efficient CFLs results in a net reduction of mercury release compared to the use of incandescent bulbs across the country. An average kWh of electricity consumed releases 0.016 milligrams of mercury (coal-fired power plants release nearly one-third of the nation's 155 billion mg of yearly mercury emissions). Over 10,000 hours of operation one CFL will consume 253 kWh, resulting in a total release of 8 mg mercury (4mg from the bulb and 4 mg from electricity production). Over that same 10,000 hours, an incandescent bulb will consume 1100 kWh, and release 17.6 mg mercury. Replacing 1 billion incandescent lamps in the U.S. with CFLs could reduce mercury emissions by nearly 10 million grams!
Technological advances over the past few years have meant that high-quality EnergyStar-labeled CFLs (such as all those sold through SafeClimate) are typically indistinguishable from the regular incandescent bulbs they replace in their functionality and light characteristics. The only differences you'll notice are your lower energy bills and saved effort from having to replace the CFL bulbs less often.