Now, LEDs, illuminate the traffic lights and cell-phone buttons, are finding their way into the home. Their residential uses are limited as yet, but look for big advances in the next few years, those in the industry say.

Terry McGowan, a Cleveland Heights, Ohio, lighting consultant and director of engineering for the American Lighting Association, said lighting is undergoing a revolution, much like what happened to electronics when tubes gave way to solid-state components. We're right on the edge of seeing LEDs show up in the living room.

As we kown, LEDs in applications such as automobile tail lights and strings of Christmas lights, forms of lighting that don't need to be especially bright. That's because, until recently, individual LEDs didn't give off all that much light. But that's changing rapidly, LEDs in residential applications such as landscape and under-cabinet kitchen lighting, and before long the technology is expected to expand to general lighting sources such as table lamps and ceiling fixtures.

LEDs are light-emitting diodes, tiny chips that light up when electrical current passes through them. They're considered an environmental boon, because they use little power and promise to last for years, maybe even decades. One of the biggest appeals of LEDs is how stingy they are with power. LEDs vary in their quality, but some rival or surpass other light sources in energy-efficiency. The white LEDs now on the market emit anywhere from 20 to 80 lumens - a measure of light - for each watt of electricity they consume. By comparison, a standard incandescent lamp produces about 11 to 17 lumens per watt, and good-quality fluorescent lamps can range from around 50 or 80. But unlike incandescent and fluorescent lighting, the efficiency of LEDs has improved dramatically in recent years, and even more gains are anticipated. It’s expected that LEDs producing 100 to 120 lumens per watt to be commercially available in the next year or two. Light output of 150 lumens per watt has been achieved in the laboratory.