Their spiral design is a symbol of "going green," the movement to make homes and living more energy-efficient. And sales of compact fluorescent lights, or CFLs, are booming: They made up 20 percent of the U.S. light bulb market in 2007, the Environmental Protection Agency says, up from 11 percent a year earlier.
Sales probably will continue rising as traditional incandescent bulbs begin disappearing from stores because of Congress' mandate that light bulbs be at least 25 percent more efficient by 2012. Wal-Mart, Home Depot, IKEA and other major retailers now sell a range of CFLs, which typically use nearly 75 percent less energy than regular bulbs.
But now that more people are using CFLs, the bulbs' shortcomings are giving some consumers pause. Consumers are raising concerns about the quality of light from such bulbs and say they often don't work well with dimmer switches, in certain light fixtures or in hot or cold conditions.
And although fluorescent bulbs are less expensive to use in the long run, some consumers are turned off by the cost: $3 to $10, compared with about 50 cents for regular bulbs. Meanwhile, retailers such as IKEA are setting up recycling programs in response to concerns about how to dispose of CFLs, which contain mercury and could pose a health hazard if they break and are not cleaned up properly.
Such drawbacks help explain why, even though one in five bulbs sold in the USA is now a compact fluorescent, a lower percentage of American homes -- estimates run as low as 11 percent -- have at least one of the bulbs.
Connie Samla, a lighting specialist at the Municipal Utility District in Sacramento, cites the 11 percent figure as a symbol of many consumers' reluctance to accept fluorescent bulbs. She says such sentiments are rooted in the problems of the early versions of such bulbs during the 1990s, when they produced a sickly green or blue light.
"They're used to fluorescent lamps flickering and having a horrible color, and they don't want to have them in their home," says Samla. Her agency now holds classes to teach residents what to expect from CFL bulbs. Some common complaints about compact fluorescents:
•They don't start out at full brightness. The bulbs can take up to a minute to reach full glow. That took a while for Kay Drey of St. Louis to get used to. "It was a little alarming at first," she says, "but then they brightened up."
•They're temperature-sensitive. If it gets much below 30 degrees, "they won't start up very quickly," Samla says. Because the phosphor in CFL bulbs that emits light takes awhile to warm up, the bulbs "like to be a little warmer. But if you get them too hot, they don't like that. They love 77 degrees: office temperature."
CFL bulbs also burn out quicker if they're in a hot environment such as inside a light fixture, says Noah Horowitz, a scientist with the Natural Resources Defense Council: "If you put it in an enclosed fixture, maybe it will last 3,000 or 5,000 hours, not 10,000." He notes, however, that even a reduced life for a fluorescent bulb tops the life of a typical incandescent bulb, usually 750 to 1,000 hours.
•One size does not fit all. The more light a CFL puts out, the bigger it must be. The CFL equivalent of a 60-watt bulb is tiny. The 120-watt equivalent is bigger and won't fit in many lamps and fixtures.