Energy-efficient LEDs could be moving into our living rooms soon

Akron Beacon Journal (MCT) - The next big thing in lighting is right on our doorsteps.

LEDs, the itty-bitty workhorses that illuminate our 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.

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

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.

You may be familiar with 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. As a result, we're already seeing 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.

WHAT ARE LEDS?

LEDs are a form of solid-state lighting, which means the light is emitted from a solid block of material rather than from a tube. In the case of LEDs, the block is made from a semiconductor material, a substance that conducts electrical current under certain conditions.

Light is created when electricity passes through the material and makes the electrons within it move.

LEDs are tiny, usually less than a millimeter across. An LED is attached to electrical wires and usually has a transparent covering that makes it look something like a miniature light bulb. Picture the little plastic pegs in Lite-Brite toys.

Early LEDs produced visible light in red and then other colors. It wasn't until early in this decade that scientists produced high-powered LEDs that emit the white light needed for residential use.

White LEDs are available in forms that produce either a cool light, similar to office-type fluorescent lighting, or a warm light that's more like traditional incandescent lighting. Most people prefer a warmer light for the home, but there's a trade-off: Warm LEDs are usually 20 percent to 30 percent less efficient than cooler ones, said Jean Paul Freyssinier, a lighting design specialist at Rensselaer Polytechnic Institute's Lighting Research Center.

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STINGY WITH POWER

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, Freyssinier said. 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. Freyssinier expects 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, he said.

The amount of light that can be produced by a single LED, however, is limited. A mid-quality LED might produce only 50 to 100 lumens, Freyssinier said _ a fraction of the 800 lumens produced by a typical 60-watt incandescent bulb. That's why LEDs are often clustered in bundles of anywhere from a half-dozen to a couple of hundred chips.

LONGEVITY BENEFIT

Another big benefit of LEDs is their longevity _ as much as 50,000 hours, by some accounts. If you used a light six hours a day, that's around 23 years' worth of use.

The life span of LEDs is measured a little differently than it is with incandescent and fluorescent light bulbs.

Unlike a bulb, an LED doesn't burn out. Rather, it dims slowly over its life. When the decline in its light output reaches 30 percent, the LED is considered spent, explained Jeffrey Dross, senior product manager of Kichler Lighting in Independence.

It generally takes 30,000 to 50,000 hours to reach that point, McGowan said.

But the life span of the chip is just one of the factors that determines how long an LED light will last. Another is the reliability of the other parts.

Unlike light fixtures we're used to, which have replaceable bulbs, LED light fixtures typically have the chip integrated into the system. So when the LED is no longer useful, you replace the whole fixture.

It's possible that the other parts in the fixture might wear out before the LED does, Freyssinier said. That's one of the biggest challenges for manufacturers right now, he said.

SPECIAL FIXTURES NEEDED

It's also important that fixtures be designed specifically for LEDs, all three experts said. Warmth in the environment greatly reduces an LED's performance, they explained, so fixtures and lamps need to be specially designed to dissipate heat.

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It's possible to buy ''light engines,'' light bulbs made with LEDs that fit into existing lamps and fixtures. But because they're used in fixtures that weren't designed for LEDs, those light engines typically suffer in terms of light output, light quality, efficiency and longevity, the experts said.

Of the light engines that have been tested, none has lived up to its claims, McGowan said. ''I think, frankly, it's a terrible idea,'' he said.

And they're expensive, McGowan and Dross noted. Dross said he has one sitting on his desk that cost $35.

COST BIGGEST DRAWBACK

Perhaps the biggest drawback to LEDs, at least at this point, is cost. In general, the LED lighting fixtures on the residential market cost about twice as much as conventional types, Dross said.

But he argues that consumers need to learn to factor in all the costs of a lighting system. That includes not just the price of the fixture, but the costs of electricity and replacement light bulbs _ or, in the case of LEDs, the savings from not having to buy them.

Greg Sedlak of Whitmer's Lighting in Copley Township, however, isn't sold on the LED lights he's encountered so far. He doesn't care for the cool, bluish color of the light produced by the under-cabinet kitchen lights his store is offering, or the way the lights reflect on shiny counters and cast multiple shadows. The store also sells LED pendant lights that produce a warmer light, but Sedlak said they produce little light and are expensive _ $488 for five pendants.

Freyssinier, however, believes LEDs make sense in many residential products now on the market. Those include task lights, some small recessed lights and outdoor lighting such as pathway and small porch lights.

Dross also likes them for picture lights, because LEDs don't emit the ultraviolet light that can damage artwork and photos.

LEARNING CURVE AHEAD

As with most new technology, expect a learning curve with LEDs.

LED lights represent a long-term commitment, so they'll probably force us to change the way we shop for lighting for our homes, Dross said. We'll need to understand and make decisions on issues like the amount of illumination and the quality and color of the light, and we'll need to live with those decisions for years.

In those regards, all LEDs are not created equal. ''The consumer really has to be wary of that,'' Dross said.

Still, the experts said we can expect LEDs to just keep getting better, cheaper and more widely available.

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LEDs, they agreed, are just a bright idea.

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BUYING LEDS

What to look for when you're buying an LED light:

_Lumens: Although we've become accustomed to thinking of light bulbs in terms of watts, that's really a measure of electricity used. Light output is measured in lumens.

How many lumens you need is a matter of preference and need. For most lighting purposes, you'll probably want lights that range from 450 lumens (the approximate equivalent of a standard 40-watt incandescent bulb) to 2,600 lumens (the equivalent of a 150-watt incandescent bulb).

_Color temperature: This indicates how warm (yellowish) or cool (bluish) the light appears to be. Most people prefer warm light, which translates to a color temperature of 2,700 to 2,900 Kelvin.

_Color rendering: The color rendering index measures how effective a light source is at making things look like their true colors. Look for a CRI score in the high 70s or above _ even higher if you're an artist or someone who needs fairly exact color rendering. A score of 100 is considered perfect.

_Energy Star label: This designation indicates a fixture or light bulb meets the government's high standards for quality and energy-efficiency. The standards for LED light fixtures took effect just last month, and manufacturers are now applying for Energy Star designation.

Source: Jeffrey Dross, Kichler Lighting

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© 2008, Akron Beacon Journal (Akron, Ohio).