In 1879, Thomas Edison made the first public demonstration of his incandescent light bulb and the invention was so perfect, nothing rivaled it for more than 100 years. However, today LED lighting is on the edge of becoming the lighting method of choice and surpassing the market dominance Edison’s invention has held for so long. The U.S. Department of Energy predicts that within 10 years, LEDs will overtake incandescent to become the main light source in residential lighting applications. Why? Because LEDs are about six times more efficient than incandescent light bulbs.
Besides being extremely energy-efficient, LEDs are durable and promise an incredible longevity — up to 50,000 hours. But admittedly, there are a few bugs to work out. These bugs include creating the customary warm white light found in residential settings, and making it market-friendly — the main obstacle facing the LED industry. Other issues holding back LED adoption for widespread residential use include managing technology challenges, providing a reasonable price-point and wedging a bright, new idea into a long-closed mind-set.
LEDs, or light-emitting diodes, are included under the umbrella term of solid state lighting (the lighting industry term for LED-based lighting). Since LEDs are on the cusp of widespread residential usage, the LED industry is working to meet projected market demand. With constant strides in research and development being made, LEDs are expected to be available for middle-market residential applications relatively soon.
“The savings, long useful life, and high quality of lighting that is possible will eventually overcome today’s obstacles. It’s really just a matter of time before solid-state lighting dominates applications from office and commercial to residential,” says Grant Harlow, director of marketing for TIR Systems, developer and manufacturer of the Lexel LED light source technology.
Another advantage of LED technology is the ability to be dimmed down from full power without the color shift incandescent bulbs experience. For example, TIR’s Lexel uses unique feedback technology to keep the color temperature (the degree of warmth or coolness) of the light consistent. Lexel-based products also may incorporate a color or color temperature change feature, so depending on the desire of the user, the fixture’s illumination can easily be changed from warm to cool.
Where Are LEDs?
Currently, LEDs are commonly used in specialty and indication applications such as traffic signals and emergency vehicles. Over the past few years, colored LEDs have been used with increasing frequency in commercial applications in colored lighting such as casinos or nightclubs. Now, LEDs are moving into general white lighting, by far the most important residential, commercial and business market.
A prime early-adopter application for LED white light is in museum or retail settings where light needs to be trained on a specific area. Since LEDs do not emit UV or infrared radiation, there is no concern of damaging sensitive paintings and fabrics. Lighting Services’ LumeLEX display lighting fixture uses TIR’s Lexel technology for illuminating displays for this reason, with the additional benefit of being able to precisely set the color temperature to best highlight the item on display.
On the residential side, many consumers generally are familiar with LEDs found in Christmas lights and flashlights in the lower-end markets. But LEDs also are rapidly moving into the area of exterior applications such as floodlights, and are now becoming available for interior applications. Their longevity makes them particularly appealing in hard-to-reach areas such as cathedral ceilings.
Designed for under-cabinet applications, American Fluorescent’s LED fixture lays in a grid pattern of 28 diodes and is covered by a clear lens. The fixture is designed to be linkable so a number of lights can run together under the cabinet area.
“One of the key attributes [of LED] is that it doesn’t emit a lot of heat, and this product can be hard-wired into new construction or retrofitted into a given structure,” says Mark Kaffee, national sales manager for residential markets, American Fluorescent.
For aesthetic appeal, LEDs can be used for low-profile lighting fixtures. Since LED light is directional, some of the bulkiness associated with traditional or troffer downlight fixtures can be eliminated.
For example, LED Lighting Fixtures has utilized Cree’s XLamp XR-E power LEDs for its first product, a 6-in. downlight for residential and commercial markets. The fixture is a recessed downlight delivering approximately 650 lumens from a fixture at 10 to 12 watts (approximately 60 lumens per watt). The product features a unique installation mechanism that allows it to be used in a standard 6-in. recessed housing and it is dimmable.
Warm Light: A Hot Topic
Producing the warm white light required for residential applications has proved a difficult task and is seen in the lighting industry as the ultimate victory. But quality residential LED lighting products will probably not be developed until solid-state lighting technology has first been proven in the high-value markets. Currently, LED illumination tends to be too harsh or “digital-looking” for consumers who demand the warmth of incandescent light.
That’s why market take-up has been so slow and why consumer reaction to LED residential products has been muted.
“Warm light has been a challenge from a couple perspectives,” says Paul Thieken, director of lighting for solid state lighting group, Cree Inc. “It produces fewer lumens so the output is less in warm light than in cool. Second, the challenge has been to create a phosphor that provides brightness with color-point stability.”
TIR Systems’ Lexel technology produces white light in a range from white to cool. However, the company and its light fixture manufacturing partners are focused more on developing Lexel-based products for the high-value commercial and institutional markets, where the quality of illumination and ability to precisely control the light output and color are important. The company says it expects more markets to open up as prices drop and energy efficiency improves.
The Heat Hurdle
One of the common concerns with LED lighting is heat, making thermal management (dissipating the heat) a crucial issue in fixture performance. With a traditional bulb, light is generated by the glowing filament which also creates heat — in fact, 90 percent of the electricity is wasted. While LEDs are more efficient, the heat they generate stays inside the semiconductor and must be extracted and dissipated to prevent the LED from overheating and failing. This is the major hindrance for LED fixture manufacturers.
For a successful LED application, fixture manufacturers must design their products so the thermal energy generated inside the LED is removed through a heat sink (an object that absorbs and dissipates heat), or by coupling the light source to the fixture so the fixture itself becomes an integral heat sink. Failure to manage the heat results in an LED that can fail or produce inconsistent results.
Since LED technology is relatively new in residential use, another hurdle will be working this technology into current manufacturing framework to make it easier and more cost-effective for the housing industry. And while solid-state lighting is most definitely heading our way, the public’s old habits will need to change to embrace the new technology. “This is a whole new lighting technology and they’re hesitant to take it on, but there’s no doubt solid-state lighting will catch on,” says John Ekis, director of sales for Lamina Ceramics.
Light at the End of the Tunnel
The U.S. DOE predicts within the next 10 years, LEDs will be the primary light source in residential settings. Recognizing the importance of LEDs in the greater energy-efficiency scheme, the DOE is actively focusing resources on the research and development of solid-state lighting products in an effort to speed up this process.
Despite this government support, LEDs still face a few hurdles before the public will willingly embrace the technology. New system requirements, price-point concerns and a 100-year-old incandescent light bulb mind-set contribute to the difficulties in the adoption of LED technology. There also are some technical complications to work out.
“It’s going to require some education, and the cost of not getting an education is going to cause difficulty with customers, warranties and service, and they will be behind the curve,” says Terry McGowan, director of engineering and technology, American Lighting Association.
Interior Designer Alene Workman advises, “Get as much information as you can about a specific product before you use it.
Do your homework and research.” Her firm, Alene Workman Interior Design, is always on the lookout for new and innovative ways to create interesting effects, so Workman has become familiar with LEDs. She adds, “Three to five years from now we’ll all be knowledgeable about what will or will not work, but for now it’s a lot of trial and error.”
To ease the adoption of LED light sources by manufacturers, TIR has ensured its Lexel light source is fully integrated and basically plug-and-play. This way, fixture manufacturers will not require major retooling of their manufacturing plants. Lexel was awarded best lighting system at Lightfair 2006.
“Until last year, LEDs weren’t powerful enough to affect mainstream lighting,” Ekis says. “It’s been about one year since LEDs have been powerful enough for desk lighting and task lighting. At Lightfair 2007 in New York in May, Lamina will introduce its 2000 lumen light source (equivalent to about a 150-watt bulb).
Today, the reality is that residential LED lighting products are only a high-end niche product for early adopters and for those who appreciate the latest technology. The future, however, promises that as research and development efforts continue, LED lighting will soon be everywhere and sooner than most people think. With efficiency six times greater than incandescent bulbs and a 50,000-hour lifespan, the future of LED lighting appears well lit.