During the past six months, I have toured many facilities that are testing various applications of LED lighting. Although this technology is improving (and this article will probably be obsolete within one year), we can draw some basic conclusions based on the technology available today. Hopefully, this can guide facility managers to either embrace or avoid this technology for certain applications during 2011.
These conclusions are based on data from research divisions of utilities who actively test LED lighting fixtures and many other energy-related technologies to determine their economic feasibility. Many utilities across the country have “technology application centers” or mini-labs that test and demonstrate energy technologies. If your utility has such a center, you may want to ask for a tour to see the applications with your own eyes. Some utilities also are testing technologies such as food processing and industrial refrigeration equipment, plug-in hybrids, renewable technologies, and industrial applications.
I have toured utility research centers on the coasts, such as Southern California Edison and New York Power Authority, as well as centers in the Midwest (Oklahoma Gas and Electric) and the South (Southern Company). All of these utilities had active programs to demonstrate new lighting fixtures in a variety of applications. Special thanks to Mr. Doug Avery, project manager at SCE, who allowed me to take some pictures of the utility’s testing activities.
Lighting Considerations
As we all know, energy efficiency recommendations that involve lighting must be sensitive to the quality of light that a retrofit will provide. Specifically, the color or “warmth” of the lamp sets an immediate mood for a space, so if you change lights and change the color, you may impact the productivity of the occupants. Of course, the other major consideration is the Color Rendering Index (CRI), which indicates the occupant’s ability to distinguish colors under a certain lamp. Beyond these two criteria, most lighting manufacturers have been trying to develop lamps that give more lumens per watt, have longer lamp lives, and are cost-effective.
LEDs are available in a variety of color temperatures providing “warm” or “cool” effects. Inside offices, homes, and other locations, many people prefer a warm atmosphere with lights that have a color temperature rating of 3500k. However, most people prefer a white light for High Intensity Discharge (HID) applications, such as a factory, warehouse, or parking lot. In recent years, the price for an LED lamp that would replace a metal halide lamp has dropped by more than 66%.
Consider the economics of replacing a 450w metal halide fixture. If an LED fixture can deliver the same lighting for an average of around 220w, the energy savings is about 50%, which would yield an annual savings of about $92 at 10 cents per kWh and 4,000 operational hours per year. Considering the fixture replacement cost, many of these types of retrofits yield about a 5-year payback, although sometimes a utility rebate is necessary to reduce the upfront cost. So, in this example, if you can get the LED manufacturer to guarantee a lamp life of at least 5 years, the LED would become practical. You may also be able to use the retrofit to obtain LEED points or achieve other green marketing initiatives.
Similar LED retrofits have been done on bridges and other outdoor applications with most utilities reporting success. In fact, one municipal client told me that after putting the LED lights on the bridges, they reduced their re-lamping interval so much that they had to conduct special bridge walks without actually re-lamping just to keep their maintenance staff practiced at high-wire walking.
LEDs are rapidly becoming effective replacements for HIDs, task lights, and other display lighting, especially applications in cold environments, such as refrigerated display cases. This summer, I did an audit of a well-known warehouse store and we found very short paybacks on replacing the fluorescent lamps with LEDs in the glass doors where they displayed milk and frozen foods.
Of course, there is a variance in the quality of LED products. I have had one type in use for 2 years without a single failure, while I have also used other types that lasted about 2 months, so the guarantee and brand name may be an important consideration. When considering HID retrofits for indoor applications such as a factory or warehouse, the T-5 or T-8 (four tubes in a fixture) can also be very attractive and may have better economics.
One place where today’s LED technology has not created an attractive economic return is with LEDs in tubes to replace a T-8 lamp. The 13-15 watts per lamp sounds impressive, but at a cost of $50 per lamp, the payback is too long. When you compare LEDs in tubes versus some of the low-wattage T-8 or T-5 technologies, usually the traditional solutions offer a quicker payback and higher reliability. However, progress is being made and the color of the LEDs in tubes is very good.
One other innovative and inexpensive solution I saw at one of the research centers was a solar tube, basically an enhanced skylight. The original installation generated too much light and glare in a particular office setting, so one engineer taped concentric rings of paper to diffuse the light. It has worked very well for about 7 years.
The State of LEDs in 2010
While LED lights are making tremendous advances in sign-related lighting, HIDs, incandescent replacements and other “under counter” (display) applications, they have not yet become a suitable replacement for fluorescent tubes. This situation is likely to improve, but LED lights in tubes will also have to compete against other technologies that may offer a better economic justification.
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