An Old Tradition Showcases the Newest Lighting Technology

March 7, 2007

To the casual observer there was not anything particularly unusual about the Capitol Christmas tree this year. The 65-foot Pacific Silver Fir was as beautiful as any tree that has graced the Capitol lawn since the tradition began in 1964. But for federal employees in the know, this year's tree was a shining example of cutting-edge technology. In addition to its 3,000 handmade ornaments, the tree featured 10,000 light-emitting diode (LED) lights-lights that are up to 90 percent more efficient than their incandescent counterparts and cost just a fraction of the price to use. In fact, this year's tree cost a mere $1 per day in energy.

Photo of the 2006 Capitol Christmas tree.
 

Use of the LED lights signaled a federal commitment to conserving energy, according to Architect of the Capitol (AOC) Alan Hantman, who served as master of ceremonies at the tree lighting ceremony. The Congress and the Office of the AOC are committed to implementing energy-saving measures across the Capitol Hill complex and already plan to use LEDs on future trees.

In 2005, approximately one-third of the lights on the Capitol tree were LEDs, as a transition to all LEDs this year. The move to LEDs was based on the clear efficiency advantage of LEDs and the fact that LED bulbs last substantially longer before needing to be replaced. While not as bright in appearance as traditional incandescent bulbs, the intensity of the color of LEDs is greater, making this year's rich red and blue bulbs a memorable image. The strings of LED lights also proved easier to mount on the tree.

Eventual widespread use of LEDs by consumers will contribute significantly to energy conservation. The conversion of electricity into useful light is one of the least efficient energy conversion processes in buildings today. Consumers and businesses spend approximately $58 billion each year to light their homes, offices, streets, and factories. Energy consumption for all lighting in the United States is estimated to be 8.2 quads, or about 22 percent of the total electricity generated in the U.S.

The Department of Energy's (DOE) Building Technologies Program has the mission of reducing the amount of electricity used to illuminate buildings by 50 percent by 2025. The Program is working in close collaboration with research and industry partners to develop and demonstrate energy-efficient, high-quality, long-lasting lighting technologies, including white-light LEDs.

Colored LEDs have been around since the 1960s and are commonly used in home electronics, automobile taillights, and even some traffic signals and exit signs. White LEDs, however, are just now reaching the point where they have enough luminous output and power to be viable for building applications and consumer use. For most general illumination applications, current LEDs cannot yet compete with traditional sources on performance and cost.

In terms of performance, many of the white-light LED products currently marketed as "energy efficient" have very low light output compared with conventional light sources. This makes them less desirable than their incandescent or fluorescent counterparts for reading lamps and other applications requiring bright light. They may be perfect, however, for applications where light is specifically directed, such as lighting outdoor steps or pathways. This is because LEDs emit light in a less diffuse pattern than conventional bulbs, which emit light in all directions.

LEDs are the clear winners when it comes to durability and efficiency. Being a solid-state device makes LEDs highly resistant to damage caused by vibration, and the best white LEDs have been found to have a useful life of about 35,000 hours, or four years of continuous operation. Researchers have also improved the efficiency of white-light LEDs to approximately 50 lumens per watt, almost four times more efficient than incandescent sources.

There is widespread variation among current white LEDs primarily because there are no consensus test procedures or performance standards for LEDs. DOE is working to change that through its Solid State Lighting Partnership with the Next Generation Industry Alliance, an industry group including lighting giants General Electric, Philips, Sylvania, and others. Working through this partnership and others, DOE is involved in the testing of LED fixtures, the creation of ENERGY STARĀ® criteria, and technology procurement programs to help bring better-quality LEDs to market.

For more information about market-available LEDs and DOE's involvement in developing better LED technology please visit http://netl.doe.gov/ssl/faqs.htm. You may also contact Brad Gustafson of FEMP at brad.gustafson@ee.doe.gov or 202-586-5865 or Jeanne Chircop of Technology & Management Services at jchircop@tmshq.com or 571-225-9912.