A Bright Future for LEDs

By Jeff Gerwing, IALD, LC, IESNA, LEED AP, Associate, Lighting Design Practice Co-Leader, SmithGroup, Inc., Detroit -- Consulting-Specifying Engineer, 10/1/2006

The domain of light-emitting diodes (LEDs) was once relegated to calculator displays, where tiny dots of light were arranged dot matrix-style to form numbers.

Today, hype about LEDs seems to be everywhere. There are a number of reasons for this phenomenon: compact size, an extended life of 50,000 or more hours, no ambient temperature effect on output, no ultraviolet or infrared emission in the light—and most notably, they can be dimmed without color shift.

Of course, there are disadvantages as well: heat-sinking requirements, problems with white LED color consistency and a higher cost compared to other light sources.

When LEDs first hit the lighting market, the industry was mesmerized by their saturated color output. The benefits of vibrant color, programming flexibility and energy efficiency in creating colored light were obvious, and LEDs immediately found a natural fit in decorative accent applications.

But can LEDs be applied beyond the realm of decorative applications? The answer is yes, and they have already begun to do so. With the hope of achieving high energy efficiency, the primary focus of LED research and development has been on maximizing white light output. While the efficiencies of traditional white light sources are close to maximum—showing minimal increases in recent years—LEDs are undergoing dramatic increases. Just a few years ago, white light efficacy, a measure of light output per watt, was in the range of 10 lumens per watt (lpw), which equals that of inefficient incandescent sources. Now, LED efficacy is around 60-65 lpw, which approaches that of compact fluorescent sources. Estimates indicate that LEDs will continue to improve in efficacy to around 150 lpw, a number that far surpasses the current efficacies of linear fluorescent and metal-halide sources at approximately 100 lpw.

With source output increasing and secondary optics providing more focused beams of light, LEDs are expanding in application possibilities. One of SmithGroup’s recent exterior lighting projects, for the Detroit Athletic Club, has been recognized with international design awards for the use of white LEDs to illuminate significant portions of the building’s façade. This is just the beginning of where LEDs can take us. Even so, LEDs are not currently a viable ambient lighting system inside buildings, which is a market share that will need to be secured in order to have the biggest impact in lowering energy consumption.

So what is the future of LEDs? As energy demands increase, they are seen as one of the most effective means of reducing consumption by lighting systems, but this shift will take time. Estimates indicate that LEDs could surpass linear fluorescent efficacy in three to four years, and lighting fixture manufacturers will need to make a paradigm shift in how they think of utilizing LEDs in ambient light fixtures. There needs to be a fundamental change in how we use these new sources to light architectural environments. Once this happens, I believe that it will take five to 10 years before we start seeing widespread use of LEDs in ambient lighting conditions as designers and owners become more comfortable with this “new” technology.