Long-range energy savings with lighting-class LED lamps

Long-range energy savings with lighting-class LED lamps

Improvements in performance move LEDs to the front lines

BY PAUL SCHEIDT
Cree
Durham, NC
http://cree.com

The dramatic improvements in performance in the solid-state lighting industry seen throughout 2007 has shown light-emitting diodes to be viable alternatives to existing lighting technologies—not sometime in the future, but today. A key factor driving the adoption of LED lighting technology is the energy efficiency it can achieve, along with long-term reliability.

According to the U.S. Department of Energy, 22% of the electrical energy used in the United States is used for lightingequal to the output of 1,000 large power plants at a total cost of $55 billion. The DOE projects that in less than 10 years, solid-state lighting will reach 150 lumens/W—10 to 12 times the efficiency of incandescent lamps and two times the efficiency of current compact fluorescent lamps (CFLs). At this level of efficiency, a 50% conversion to LED lighting could save 6% to 7% of the country’s total electrical energy use (a $17 billion annual savings).

While many people do not have a problem believing in the potential energy savings of LED lighting over the long term, they do not think that LED lighting can offer much real energy savings today. And, of course, the initial purchase price of LED-based lighting today can be several times that of traditional lamps, limiting the adoption of LED lighting to date. But initial installations illustrate that the projected energy savings are real.

Last fall, WalMart announced that it would retrofit refrigerator cases in more than 500 of its stores with LED lighting systems. The company attributes 66% of its operating expenses to purchased electricity, and estimates that the move to LED lighting in refrigerator cases will save $3.8 million a year.

In February 2007, Cree and the city of Raleigh, NC, announced a joint initiative to test, deploy, and promote LED technology in a variety of general lighting applications. The “LED City” initiative (which has added Ann Arbor and Toronto to the roster) is designed to create a “living laboratory” to evaluate the economic, environmental, and esthetic benefits of LED lighting for the residents of these cities.

The first Raleigh LED City project was an installation in December 2006 on one floor of the city’s municipal building parking deck. Cree supplied the LEDs, and Lighting Science Group Corp. (www.lsgc.com) supplied the fixtures. The floor equipped with LED lights uses at least 40% less energy, as measured by Progress Energy, Raleigh’s primary electric utility provider. Plus, according to Mindwave Research’s survey results, users of the parking deck felt that the quality of light in the garage is greatly improved and it is a safer place.

The directional nature of LED light can play a big part in how efficient an overall fixture is.

Cree has announced plans to convert all lighting at its Durham, NC, headquarters and manufacturing facility to LED. As a result of the conversion’s first phase, the parking lots, entry ways, lobby, and conference rooms at its headquarters building are now 100% lit by LEDs. The combination of the energy savings, plus reduced maintenance and disposal costs, and the improved environmental impact demonstrate a real alternative to traditional lighting.

A study of the energy usage before and after the lighting conversion indicated that the new lights use 48% less energy than the combination of incandescent, fluorescent, and high-pressure sodium lights they replaced.

When considering adopting LED technology, brightness, cost, and lifetime are the first issues evaluated. Energy efficiency considerations have moved to the forefront now, due in part to government-funded research in the area of energy conservation, as well as the increasing awareness of lighting inefficiency, reflected in the development of standards and legislation requiring efficient light sources.

The billions of dollars of potential annual energy savings by switching to LED lighting has spurred many government-funded research initiatives, such as the Next-Generation Lighting Initiative and “Light for the 21st Century.” These programs bring together government agencies, industry organizations, academe, and laboratories to accelerate development and implementation of solid-state lighting.

For now, LEDs are an option that should be given due consideration, but in the near future, they may become a necessity. All around the world, states and nations are becoming aware of how inefficient many current lighting technologies are. Governments in the United States, Canada, Europe, and Australia have responded in the form of “light bulb bans” generally, legislation regulating or eliminating the sale of incandescent and halogen light bulbs by a certain date.

While increased awareness of the inefficiency of those light sources is good for increasing the adoption of LED light, regulations that focus on enforcing performance metrics instead of banning a specific technology are even better. California’s Title 24 standard is an excellent example of this style of legislation. In general, Title 24 provides a set of mandatory regulations covering all aspects of building construction. The Residential Lighting portion of Title 24 requires a high-efficiency light source to be used in several areas of the home, including the kitchen and bathrooms, but does not specify what technology has to be used.

The newly completed U.S. Department of Energy Energy Star standards for solid-state lighting luminaires place restrictions on the total efficacy of the luminaire, not just the efficacy provided by the light source. Keep in mind that Title 24 and Energy Star are very different. Title 24 is enforceable government legislation, while Energy Star is a voluntary certification. Current interest in regulating the efficacy of lighting is likely to create legislation that uses one of these two standards as a template.

Since LEDs are a directional light source, they generally create a more efficient luminaire than one based on an omni-directional light source, such as a CFL light bulb.

Since LEDs are a directional light source, they generally create a more efficient luminaire than one based on an omni-directional light source, such as a CFL light bulb. The directional nature of LED light can play a big part in how efficient an overall fixture is. While other light sources, such as high-pressure sodium, may be more efficient at the light source level, in practice LEDs will deliver usable light more efficiently. Today’s best-in-class cool-white power LEDs are reaching to almost 100-lumens/W efficiency and will be able to deliver a real-world 70-lumens/W usable light output in directional applications, such as parking lot lighting and indoor downlighting.

“The continued improvement in LED lighting performance shows no sign of abating,” said Jim Brodrick, lighting program manager for the U.S. Department of Energy’s Building Technologies Program. “As the performance and efficacy improves, LED lighting has the potential to make a significant contribution to reducing this country’s energy consumption.”

For more on LEDs, visit http://electronicproducts-com-develop.go-vip.net/opto.asp.