Ode to a Diode
National Christmas Tree Joins Other Outdoor Light Displays In Using Energy-Efficient LEDs That Save Electricity -- and Money

By Daniel LeDuc
Washington Post Staff Writer
Friday, December 7, 2007

It takes a while for a tree to be green.

For decades, the National Christmas Tree was heartily chopped down from forests throughout the nation and trucked to the White House to be decked out in lights and ornaments. Then someone finally had the idea to plant the tree, so it would grow each year; the current tree has stood in place for 28 years.

Yesterday, the Colorado blue spruce passed an ecological milestone. When President Bush flicked the switch, those were not filament-burning bulbs that bedazzled the thousands who thronged the Ellipse for the annual tradition; they were glowing, energy-efficient light-emitting diodes.

It was a first for the national tree and part of a new holiday tradition throughout the region, as public Christmas displays switch to bulbs that illuminate by chemical reaction. The Christmas tree at the Capitol switched two years ago. All the Christmas lights in the Maryland State House and governor's residence in Annapolis made the change this year.

Same for some of the most popular, crowd-drawing displays in the area. The new display at the National Zoo is all LED, as is the Bull Run Festival of Lights in Centreville. The Garden of Lights at Brookside Gardens in Wheaton has exchanged nearly half of its 700,000 lights for LEDs and plans to complete the rest in the coming years. The Festival of Lights at the Mormon Temple in Kensington has replaced more than three-fourths of its half-million lights and hopes to finish the rest next year.

"We've had people come in and say, 'Where did you get those colors? The blue, the chartreuse -- they're beautiful,' " said William Child, director of the visitors center at the temple. "They're much brighter. You can tell if you turn them on in the daytime."

The LEDs have become available commercially for residential use only in the past year or two, but retailers report a steady increase in sales. The lights offer lots of advantages beyond significant energy savings. Although slightly more expensive to purchase, they can be made in a rainbow of colors and last much longer than old-fashioned lights.

Of course, this all means an end to some other Christmas traditions, such as decorating the tree, plugging in the lights and standing back to discover that one strand, way near the top, is out.

Or the merriment of burnt fingers from grabbing hot lights. Or the comfort and joy of blown fuses from overloaded circuits.

LEDs are cool to the touch and generally use about 10 percent of the energy of a standard incandescent bulb. They're also nearly indestructible.

Larry Smith, grounds supervisor at the Mormon Temple, said that when he began buying LEDS, the manufacturer told him he could drive a truck over them and they'd still work.

So he bought some and sure enough, "I ran over them in the parking lot and brought them in and plugged them in. They worked just fine. We expect to get 10 more years out of each string than we would otherwise. The color doesn't fade out because there's no heat," Smith said. "They're worth the investment. You put them up and they're up. You don't have to worry about strands going out."

Traditional lights burn white and get their color from filters. But LEDs are created out of semiconductors; changing their composition changes their color, across the spectrum from blue to red, said Nadarajah Narendran, director of research at the Lighting Research Center in Troy, N.Y. They don't heat up. Instead, the atoms have charges that combine and release light.

In strictly technical terms, Narendran explained, "They have a better sparkle."

Yesterday, just before 6 p.m. 20,280 LEDs, each bulb about the size of a fingertip, clicked on to applause from the crowd.

"This is the first time I've seen it in person. It's an awesome experience," said Craig Durmon, who was visiting from Hot Springs, Ark. He and other spectators had heard of plans to light the tree with LEDs, and several said the lighting was as good as ever.

"It looks great," said Rod Rosenboom, visiting from Parrish, Fla. Noting the extended life of LEDs, he said, "You can pass them on to your kids."

The task of designing the tree for the past 12 years has fallen to Kathy Presciano, a lighting specialist for General Electric.

In addition to the multicolored lights in the branches, there are red LEDs in the garland, and the three-dimensional star on top glows with white LEDs.

"It has a dual purpose," Presciano said. "We want to create a beautiful icon. . . . At the same time, we need to think about how to do this smarter." She said the national tree should use about 60 percent less energy this year than in previous years, thanks to the LEDs.

"It looks traditional, but behind the scenes, it's really efficient."