Is LED lighting the right choice?
At the Madison Christian Community Church, an outdoor LED installation has been very successful.Is LED lighting the right choice for you?
According to the Energy Information Administration, the U.S. spends roughly 25% of its electricity dollars on lighting, making that a logical place to look for opportunities to save energy and money. Light emitting diode (LED) technology (also referred to as Solid State Lighting or SSL) is attracting a lot of attention because of its potential for long life and impressive energy savings, but those benefits don't necessarily make it the right choice for every installation. For a better understanding of the technology, we spoke with Liesel Whitney-Schulte, LC, lighting project manager for business programs at Focus on Energy, a public-private partnership that helps consumers and businesses learn about and integrate energy efficiency and renewable energy projects.
MGE: What are the advantages of Solid State Lighting?
Liesel Whitney-Schulte: LEDs were originally used for small indicator lights on computers and equipment: they're basically a microchip designed to emit light. The technology has advanced so that they can actually be used as a light source, and they do offer quite a few advantages: they're dimmable and directional—which makes them great for task lighting or situations where you want pinpoint control—they go on instantly and they can stand up to extreme cold. They're also available in a large variety of colors and they fade gradually rather than failing. They have the potential for very long life and, unlike fluorescents, they don't contain mercury.
MGE: Can I just put an LED bulb in an existing fixture?
LWS: You could, but may run the risk of compromising device life and light output and be disappointed. LED light may be cool to the touch, but the junction point of the LED and the microchip that controls it generates a lot of heat. This means that you need a fixture with a heat sink—usually a substantial piece of metal—designed to pull heat away from the junction point. The luminaire should be designed as a system to utilize the directional nature of LED light, optimize efficiency to get the light where it is needed and mitigate heat. The cost for an SSL luminaire can easily top $100 each.
MGE: I've also heard that color can be an issue with LEDs.
LWS: According to the Department of Energy (DOE), desirable whites—those that are more neutral or warm rather than the cooler blues of the most energy-efficient LEDs—tend to be less energy efficient and to have a shorter life. You'll have to balance energy efficiency and color preference. Another consideration for color is that there is a wider variety "white" colored LED, and poorly matched LEDs could have an undesirable effect on surfaces they are lighting. Most applications demand a consistent white.
MGE: A lot of manufacturers say their lamps will last for 50,000 or even 100,000 hours. Is that true?
LWS: For some products, that is true - but don't be too easily swayed by impressive stats. These products typically haven't been around long enough to have been tested for this full time period. Ask if the life rating is based on just the LED device or the whole SSL luminaire. If it's just the LED chip, then the rating may not accurately represent how it will actually perform in the lamp or luminaire. And it's critical to know the conditions under which the testing took place and how useful life was defined: the DOE defines end of life as the point when the luminaire is delivering 70% of its initial light level.
MGE: What are some things to consider when deciding if LED is a good choice?
LWS: Start with the energy efficiency and cost of what you're replacing. If you're going from an incandescent light to an LED with an appropriate heat sink feature, your savings might be dramatic. If you switch from metal halide or fluorescent to a warm-white LED, you might be disappointed because of these incumbent light sources.
Know that you're going to get the best results from purchasing complete fixtures, not just lamps. Thermal management is critical; without this your product life and light output will be severely compromised. A standalone bulb, screwed into an existing fixture, will not always deliver the results you're looking for. Ask the manufacturer/distributor to explain how the product is managing heat. And ask to see independent test data as defined by the DOE specs for ENERGY STAR® qualified SSL products. A reputable manufacturer should have this data and be able to explain how testing was conducted and should define useful product life as 70% of initial light levels.
I'd strongly recommend doing a color and product life test before you make a large investment in SSL products. Work with the manufacturer or distributor to choose an SSL luminaire that meets your site needs and then do a test run for three months. Have a light level reading at the start and three months in: there should not be an appreciable difference in light quality or amount. Is the light color right in your environment? Is the light quality acceptable? If you're considering a substantial investment, try two or three different types.
A tale of two LED installations
We spoke with two companies who recently installed LEDs at their facilities.
At the Madison Christian Community Church, an outdoor LED installation has been very successful.
"We're estimating that this installation will save us about $4,000 in energy over the life of the system and about $800 in lamp replacement labor versus a comparable installation using metal halide," said Tom Mathews, facilities manager for the church.
In addition to energy savings, Mathews is also very pleased with the light quality the LED delivers. "It's a very white, even light with no hot spots. And we like the fact that you can direct exactly where the light is going to minimize light pollution."
To boost energy savings, the church has wired these external lights into its security system and uses a photocell to automatically limit light use to the hours after dark.
Mathews worked with a local consultant to set up the LED system and is pleased to report that testing after the installation shows the church can get the amount of light it needs with fewer fixtures. "We're finding that the manufacturer probably underestimated the amount of light these fixtures deliver, so we're going to use them to replace some older mercury vapor lights that we have in a different parking lot. This will mean even more energy savings for us."
For the Glass Nickel Pizza location at 2916 Atwood Avenue in Madison, the decision to go with LED has definitely been a glass half-filled. Exterior lights have worked well, but the interior installation has been another matter.
"We chose lights that were supposed to last 10,000 hours and four weeks afterward we were already having dimming," said Glass Nickel co-owner Tim Nicholson.
Shorter product life is probably attributable to the fact that only the lamps were updated, not the fixtures. The old fixtures are unlikely to have the heat sink features needed to ensure full product life and light quality.
Nicholson has also had mixed results with light hue. "We ended up pulling the lights out of the dining room because of the ambiance—they're too blue for that setting though they work very well in the kitchen."
"We're definitely not giving up on LEDs but it's obvious that some changes need to be made before they'll be a good fit for us inside," said Nicholson.
For additional information about LED technology, please visit the Department of Energy Web site.
Fact sheets: http://www.netl.doe.gov/ssl/publications-factsheets.htm
Product testing results: http://www.netl.doe.gov/ssl/comm_testing.htm
Standards: http://www.netl.doe.gov/ssl/usingLeds/measurement-series-standards-performance.htm
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