LEDs - light-emitting diodes - are emerging as a more appealing alternative to compact fluorescent lamps (CFLs). These semiconductor-driven bulbs consume less power and light instantly compared with gradually brightening CFLs. Unlike CFLs, they don't contain toxic mercury and their designs are more streamlined than the squiggly fluorescents."LEDs are certainly more attractive than the curly CFLs. They can be dimmed more readily and last longer," says Bethesda homeowner Dana Shoenberg, 45. She and husband Jeff Rackow, 46, who are both attorneys, recently replaced ceiling lights in their kitchen, living room and hallway with LEDs. Instead of going to a hardware store to figure out the right products to buy, the couple tried a new lighting business offered by the local audio-visual company Bethesda Systems. The service, called the LED Diet, aims to slim down electricity bills by helping homeowners choose the right energy-efficient lights and installing them. "They came to our house and tested various fixtures and bulbs during the day and night so we could see the quality of light," Shoenberg says. "We really appreciated being able to try a range of bulbs to see which ones looked the best to us without having to purchase them all to test them out."Jonathan Stovall, co-owner of Bethesda Systems, says the LED Diet was launched in June "because of the confusion over lighting choices." Since the Energy Independence and Security Act became law in 2007, familiar incandescent bulbs have largely disappeared from the market because they don't meet new efficiency standards. Consumers are left to sort through an array of lighting choices to determine the brightness, color and environmental safety of replacement bulbs. "The shape of the LED bulb, the color and brightness of light, and life span varies from manufacturer to manufacturer," Stovall says. "It's like the Wild West out there."He and his team of "dietitians" make house calls to assess lighting conditions and recommend LED replacement lamps and fixtures from about 35 manufacturers. Designs range from a small, flame-tipped chandelier bulb ($13) to a linear, trough-shaped fixture ($150) for a utility room. Installation is free with the purchase of the LEDs."We sell bulbs and fixtures that you can't find at Home Depot or Lowe's," says Stovall, pulling out a domed ceiling fixture and a light bulb for a three-way lamp. "The brand isn't important. It's how it looks in the room." Homeowners should be prepared to spend much more than they would for old-style incandescent lighting. A single LED bulb for a recessed ceiling fixture can cost $55. Shoenberg and Rackow spent $500 on nine dimmable LED bulbs, each producing 1,200 lumens, or the brightness of a 120-watt incandescent bulb. At Home Depot, the least expensive LED bulb, a 40-watt equivalent, is priced around $10. "This sticker shock is keeping people from buying LEDs," says lighting designer Paul Dorsey of the D.C. store Illuminations. "But if you think about an LED as a mini-computer that emits light and a more permanent light source, then it is very cost-effective."Some LED bulbs are promised to last two or three decades, and Stovall says an LED can save $267 in energy costs over a comparable incandescent during the lifetime of the bulb. But LEDs can lose brightness over time and many of the products are too new to have their longevity claims proved through time-tested, practical applications. "Not all LEDs are created equal. It's still an emerging technology," Dorsey says. He predicts the prices of LEDs will decrease as the lighting becomes more prevalent but warns, "It's not realistic to think that they'll be in the price range of disposable incandescent bulbs." Deborah K. Dietsch is a freelance writer.