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LED: A-B-C? 1-2-3?
A new generation of lighting products known as light-emitting diodes (LED) is improving at an exceptional rate, widening the range of applications in institutional and commercial facilities.
As a result of these recent advances, maintenance and engineering managers are working to determine the impact this new technology will have on their facilities, operations and departments. The results of many applications are likely to include longer performance life, lower energy costs and decreased maintenance.
Measuring the Market
The total LED market in 2005 was $4 billion. General lighting applications made up only 6 percent, or $240 million, of this market, but managers can expect to see such projects grow to $1 billion by 2010.
Manufacturers of LED systems have made significant gains in the efficacy in lumens per watt (LPW) of their products. But a recent pilot study by the U.S. Department of Energy (DOE) showed that individual LEDs measured much lower efficacies.
The DOE’s tests examined two downlights — a task light and an under-cabinet light. Its tests found that all four fixtures fell far short of claimed output in terms of LPW. The manufacturers claimed lighting efficacies of 36-55 LPW, while the pilot test found efficacies of 11.6-19.3 LPW, placing them below compact fluorescents (CFL) in efficacy. The study implies that manufacturers rely on measurements of how much light an isolated LED produces, rather than how much light an LED fixture actually delivers.
When examining LED efficacy, managers need to be sure system efficacy is calculated and reported in order to ensure that the power of all components is accounted for. Also, electrical and thermal design is critical to actual performance.
LED manufacturers continue to work on delivering higher brightness and better efficiency for general LED lighting applications. For now, long-life niche products on the market — many with estimated usable lives of 60,000 hours — can help managers reduce maintenance costs.
Though LED technology has been around for quite some time, many practical applications for these products in facilities have emerged only recently. Among the applications managers can consider are these:
INCANDESCENT REPLACEMENTS. These replacements for elevators using R-12 lamps and for 10-watt (W) or 20-W MR-16 lamp replacements. A 3-W LED replaces a 20-W MR-16. They are powered from the same 12-volt (V) — AC or DC — source. Some earlier models used LED clusters, but new models use one point source, providing a more focused beam. The product-life rating varies by manufacturer but often is 10,000-50,000 hours.
LED replacements are available in decorative lamp shapes. For example, G25 direct incandescent replacements are available in standard Edison-screw bases and use 1–1.7 W, depending on the size. They are expected to operate 11 years and provide the means to integrate ornamental illumination into maintenance-intensive applications.
WAYFINDING APPLICATIONS. A portable fabric sign is available with four chevrons, each lighted with nine LEDs. When a 9 V battery is connected, the LED chevrons chase across the sign to indicate the way out. Building safety engineers will find this portable sign an important product because of the growing emphasis on speedy building evacuations. LEDs — including an exit sign that uses one 1W red, side-emitting, high-power LED and an emergency unit with LED heads that only draws 3W — are changing emergency lighting. The unit uses high-brightness LEDs that provide more than 45 lumens. A rechargeable battery provides 120 minutes of backup, exceeding the 90-minute requirement of UL924.
PORTABLE DESK LIGHTS. These desk lights, now entering the market, range from useless to rather interesting. Two products include heat-management technology. One desk lamp incorporates a heat pipe and a small fan to draw heat away from the LEDs, while another uses a dimple-and-chimney strategy; namely, a bump over each LED with a small hole to allow the heat to escape.
STRIP LIGHTS. These strips replace fluorescent, halogen, and incandescent fixtures, and they typically are 6-inch-wide strips with embedded, bright LEDs that can be ordered in lengths of 5 inches to 8 feet. They produce about 450 lumens per foot, use about 8 W per foot — about 56 LPW — and are available in five color temperatures, from 2,500 K to 7,000 K and come with a color rendering index rating of 80–85.
HOLIDAY LIGHTING. LED holiday lighting products are coming on strong and are fast finding a niche, mainly due to their durability, brightness, and energy savings. Lower-wattage LED bulbs use about 0.04 W each, which is 10 times less energy than incandescent mini-lights and 100 times less than standard incandescent bulbs.
Replacing standard holiday lights with LED lights reduces energy by at least 95 percent and reduces the time needed to replace burned-out bulbs. They also last up to seven times longer — up to 200,000 hours when used indoors — although manufacturers only provide warranties that range up to 10 years. Controllers provide flashing, twinkling, fading and other animation effects. LED strings can cost two to three times more than incandescent strings, but bargains are available on the web.
Besides tree lights, candle-shaped LED models can reduce energy use, remove the risks presented by real candles and avoid creating a mess. Some products look like real candles in a frosted glass container. Inside, two LEDs provide the light source. The candle’s light base, which consists of a rechargeable battery, provides a smooth glow similar to that of a candle flame for up to 10 hours.
OBSTRUCTION AND BEACON LIGHTS. For applications on tall buildings or communications towers, LED obstruction and beacon lights feature long life, extending the maintenance interval to change short-life incandescent lamps with specialized labor. Some LED units are strobes for use on construction equipment.
PARKING. The City of Raleigh, N.C., is replacing high-pressure sodium (HPS) low-bay fixtures in its parking garages. The new 75-watt, low-bay fixtures contain an array of long-life, high-reliability LEDs to ensure maximum performance. These fixtures use 25-50 percent less power than the HPS fixtures they will replace. The LED fixtures also will provide a white light with excellent color rendering, and managers expect them to last up to three times longer than HPS bulbs and ballasts.
For more information on identifying LED applications, see sidebar below.
When considering solid-state lighting (SSL) — which includes LEDs — managers need to avoid simply thinking about replacing existing applications with LEDs. Instead, they can focus on bringing light to areas that had been difficult or impossible to light because of the constraints of existing lighting technology.
Many applications can benefit from LEDs when the implementation is appropriate and takes advantage of the unique characteristics and performance of LED technology. SSL manufacturers are anxious to get feedback from facilities, and together new and creative design solutions to lighting challenges can emerge.
SSL products promise long life, but managers can expect some difficulties during the transition. Testing new products before they are proven in the marketplace can be risky; proven products will have gone through the UL listing procedure. Also, managers might need to consider more labor to track performance.
John L. Fetters is president of Effective Lighting Solutions Inc. in Columbus, Ohio. He presents an LED module in the online seminar “Advanced Lighting Retrofit Options” provided by the Association of Energy Engineers, www.aeecenter.org
Where LED Can Work
The U.S. Department of Energy has developed the following guidelines for managers to use in identifying lighting applications in which light-emitting diodes (LED) might make sense in the near term:
— John L. Fetters