LEDs get public's green light for holidays

When New York City Mayor Michael Bloomberg helped light the Rockefeller Center Christmas tree last month, the 84-foot-tall Norway spruce came alive with 30,000 twinkling lights. For the first time, the famous tree was illuminated with energy-efficient LEDs, or light emitting diodes, rather than traditional light bulbs.

Major displays such as the Rockefeller Center tree, the National Christmas Tree in Washington and even the New Year's Eve Ball in New York's Times Square are making the move to LEDs this season.

But when it comes to environmentally friendly holiday lights, many homeowners are already out ahead.

Manufacturers and retailers report that consumer sales of the efficient lights have been growing for years. Fans say the lights' versatility, safety and energy efficiency could soon make incandescent bulbs a ghost of Christmas past.

Colored strings of Christmas lights date back to the early days of electric light bulbs, but they were too expensive to really catch on with homeowners until the 1930s. We've been using variations on those early bulbs — smaller versions of standard incandescent lights, with a colored coating on the glass — ever since.

But colored LEDs started appearing on America's wreaths, eaves and trees earlier this decade. Colors, brightness and variety have improved every year since, says Jim Anderson of Philips Lighting, helping to bump LED light strings to 10.5% of his company's holiday light sales, up from 3.5% just two years ago.

"LED stringers have been selling hot and heavy for the last two years," says Mike Streb of ChristmasLightsEtc.com. "I was concerned they might be a fad at first, but it looks like they're here to stay."

For the big public displays, the main selling points of LED holiday lights are energy efficiency and longevity. LEDs can run on 10% or less of the electricity that regular bulbs require and last much longer. For consumers, the convenience of lights that won't break or need replacing may be even more important.

At the National Christmas Tree, for example, GE Consumer & Industrial lighting designer Kathy Presciano says that traditional 26-light strings burned at 125 watts and lasted for about 1,000 hours. "The same size string in LED lasts 20,000 hours and burns at 2.3 watts," she says.

At home, that means spending 30 cents or less on electricity to light a full-sized tree for the entire holiday season.

The secret lies in how LEDs make light. Ordinary incandescent light bulbs work by channeling an electrical current through a wire filament — the part of the bulb that eventually burns out — that glows brightly because of electrical resistance. It's the same principle behind a toaster, notes Auburn University electrical engineering professor Mark Nelms, "and it's inefficient because more of the energy goes into making heat than making light."

LEDs work on a completely different principle, Nelms notes. The lights are actually small semiconductor chips, similar to computer chips. Thanks to the configuration and chemical composition of the chip, or diode, electrons flowing through it lose energy along the way, giving it off as colored light rather than heat.

And unlike incandescent bulbs, which produce a white light and then use colored glass or coatings to filter out all but the desired hue, "with LEDs, the color depends on the materials in the diode," says Nelms. Because there's no glass bulb, the LED lights are almost indestructible.

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