A compact fluorescent light bulb (CFL bulb) is a type of fluorescent lamp which screws into a regular light bulb socket, or plugs into a small lighting fixture .

Their advantages over regular incandescent light bulbs are their long life (6,000 to 10,000 hours instead of 750 to 1,000 hours) and energy savings due to their lower power; for example, a 25 watt CFL bulb gives the same amount of light as a 100 watt incandescent bulb, that is, approximately 1700 lumens. However, a large amount of the electrical energy is still converted into heat; the emitted visible light in this example is about 11 watts.

Introduced in the U.S. and Canada in the early 1990s, compact fluorescent lights have been steadily increasing in sales for several years, as their quality increases, size and price decrease, color rendition improves, and more people find that the savings in energy costs (even indirectly, by saving on cooling) outweighs the initial cost.

The most common power ratings of compact fluorescent bulbs are 13 watts (roughly equivalent to a 40 watt incandescent bulb), 15 watts (analogous to a 60 watt incandescent bulb), 20 watts (provides the same light as a 75 watt incandescent bulb) and 25 watts (parallels a 100 watt incandescent). Sometimes intermediate denominations, such as 18 and 23 watts, are also encountered, as are very bright bulbs, some as large as 85 watts. However, CFL bulbs with power ratings of higher than 26 watts have yet to gain a significant following with either American or Canadian consumers.

In addition to different power ratings, compact fluorescent bulbs are also produced in varying shades of color. The color designated "warm white" provides a light which is extremely similar to that of an incandescent bulb, somewhat yellow in appearance; "soft white" bulbs emit a yellowish-white light, "cool white" bulbs more of a pure white tone, and the light from "daylight" bulbs is slightly bluish-white (in addition to the descriptive names outlined above, color is also denoted using a quantitative color temperature scale; the higher the number, the "cooler" the shade, with warm-white bulbs typically being rated at 2,700 K, soft-white bulbs around 3,500 K, cool-white bulbs at approximately 4,100K, and daylight bulbs as high as 6,400 K — the "K" standing for "kelvin"). Less commonly, compact fluorescent bulbs are manufactured in colors such as red and green.

CFL bulbs also provide a benefit to the environment based on their energy savings over a regular incandescent light bulb. According to the U.S. government's Energy Star website, if every household in the United States replaced just one incandescent bulb with a CFL bulb, it would have an environmental impact equivalent to removing one million cars from the American roads. [1]

The newest version of the CFL bulb is the RFL, or radiofluorescent type, which uses radio waves instead of ultraviolet light to excite the phosphors. Another variant of the CFL bulb is coated with titanium dioxide, which the manufacturer claims reduces odors by ionization and oxidation.

In 2003 the Canadian electrical company BC Hydro distributed thousands of compact fluorescent lightbulbs for free, and currently offers a rebate program for their purchase: http://www.bchydro.com/powersmart/ . Numerous utilities operate similar reduction-of-usage education/advertising programs.

External links

• Energy Star homepage
• Energy saving calculator
• Energy Savings