Lighting evolves based on need. Incandescent made way for brighter fluorescent. Fluorescent made room for solid-state lighting (SSL). The next big idea may be light-emitting diodes (LEDs). While they are an SSL source, LEDs are new to general lighting applications. They are advancing rapidly, while being both commercially available and, in development, as robust research and development ramps up for this lighting source.
“LEDs represent the digitization of light,” said Avraham “Avi” Mor, partner at Lightswitch Architectural Chicago, a lighting design firm. “That’s a big deal. It’s not the reinvention of the light bulb. It’s the next generation of lighting technology.”
Today’s need for lighting rests on providing products that use less energy, provide longer life and offer broad flexibility without sacrificing lumen and color temperature. LEDs appear to be tailor-made to meet this challenge. These light sources are reported to offer lumens per watts (LPW) or efficacy of 25 LPW to more than 80 LPW. By comparison, incandescent ranges between 5–10 LPW. Longevity differences are just as stark. LEDs, factoring in dimming and temperature, can last anywhere from 25,000 hours to 100,000 hours. Incandescents stand at roughly 1,000 hours. Dimming LEDs down to 50 percent of their light output can save nearly 50 percent of energy usage, while allowing them to run cooler and possibly tripling their life, according to “Controlling LEDs: a Technical White Paper,” by Amanda Beebe and Ethan Biery, Lutron Electronics Co. Inc., January 2011.
ELECTRICAL CONTRACTOR conducted a market research study among its subscribers in late 2010, administered by Renaissance Research & Consulting, New York, to gain insight into how electrical contractors were performing their roles as changes took place in lighting options. When it came to LEDs, those surveyed indicated they would know that LEDs are ready for mainstream use when the price comes down (19 percent), based on performance/quality (10 percent), and when they learn more from a sales/data perspective (11 percent) or from personal experience (5 percent). One-third of electrical contractors say that LEDs are currently ready to replace incandescent lamps, compared with about two in 10 for either compact fluorescent lamps (CFLs) (23 percent) or fluorescents (19 percent).
Waiting for large-scale acceptance
Electrical contractors’ feedback on their perception of LEDs helps explain why this lighting revolution is only simmering and not boiling. When used for general illumination, LEDs and their required drivers are expensive. Depending on the lamp or fixture, the price can be 10 times as high when compared to traditional lighting sources. Controls compatibility remains a challenge, as well. Yet those limitations aren’t necessarily nonstarters.
Aggressive research and development and growing acceptance in some markets, notably commercial, are helping to meet LED hurdles. Advances are coming at a rate of months rather than years. Harvey M. Bernstein, vice president, Global Thought Leadership & Business Development, McGraw-Hill Construction, reports that, “By 2020, LEDs are expected to cover 46 percent of the $4.4 billion U.S. market for lamps in the commercial, industrial and outdoor stationary sectors.”
“Now a number of players make really good products, especially in downlights,” Mor said. “Manufacturers are starting to use a ‘can you tell the difference?’ approach between incandescent and LED light. XICATO does this in their trade show booths where half is lit by incandescent and the other by its LED Spot modules. You are challenged to differentiate which light is which.”
The elements of LED
The wavelength (or color) of an LED is typically red, blue, amber or green with lumen outputs of 10 to 200. For general lighting, blue LEDs (phosphor) are used and have progressed to offer a pleasing white light. That’s accomplished through a layer of yellow phosphor placed over the LED chips to absorb some of the blue light. The mix of yellow and blue yields a perceived white light.
Standard LED lamps are socket-based for easy replacement of incandescents or CFLs. The bases have drivers that determine “dimmability.” LED fixtures have an external driver that is often supported by a lighting controller. Drivers are either constant-current (350 mA, 700 mA and 1A), popular for downlighting and akin to a fluorescent with ballast; or constant-voltage (typically, 10V, 12V and 24V), suitable for cove or undercabinet lighting. The design of the LED array determines the driver. A quality driver will help avoid voltage drop and noise to ultimately provide smooth lighting. Newer, forward-phase-control dimmers have helped remediate these problems and are UL-listed for LED operation, according to the Lutron white paper.
“Office spaces are the No. 1 place for LED lighting right now,” said Kelly Cunningham, outreach director for the California Lighting Technology Center, University of California, Davis. “As is happening in residential applications of LED lighting, layering light is now a popular strategy for offices. Instead of a mass blast of fluorescent ceiling lighting, you might start with LED recessed for the ceiling, mixed with drop-pendant lighting over a reception desk, then down to an LED task light and undercabinet for the desk. LED is providing options to meet light where you need it.”
She also noted LED adoption in corridors, stairwells and office bathrooms around mirrors.
“LEDs fit really well in a corridor. We’ve been working on creative applications of occupancy sensors allowing the LEDs to dim down 20 to 30 percent when the corridor isn’t being used, then increase as the corridor is in use. The UC Davis campus wants to try this where it makes sense. Washington State University and other campuses are interested, as well. Now we have a possible new market.”
Similar to the indoor corridor, adaptive lighting could be extended outdoors and networked with indoor lighting. Cunningham offered a scenario where appropriate parking lot lighting might increase as someone approaches a front entrance, which in turn activates lights in the front foyer. It’s a predictive pathway that reads where you are going. Such an idea may be three to five years away, but it illustrates the flexibility of this light source.
“Street lamp color temperature and glare challenges are settling out,” she said. “LEDs could be created that use blue-white light when needed, then revert to amber. If you are going to replace outdoor parking light entirely with LED, you can compete, in some cases, with the fluorescent induction lighting using dimmable LED lamps that last as much as 100,000 hours. Some decent LED units are $300–$400.”
Cunningham also noted other promising markets from assisted living residences interested in LED for their color temperature and energy savings to classrooms and retail, including freezer and refrigerator cases equipped with occupancy sensors.
“It’s all about picking the right luminaire that makes the most sense,” Cunningham said. “Maybe it’s an integration of LED into a mix of light.”
Mor has found that, while going full LED on a project may be desirable, it isn’t always realistic.
“When you have a budget, you have to decide where you want to spend your money. We wanted to go all LED on a 500-unit hotel project but realized we needed to scale back our ambitions and use LED selectively. Some of it was due to a lack of driver open protocols for dolly dimming. Some was cost. We ultimately used LED for cove and landscape lightings.”
The wheat from the chaff
“You hear of ‘green washing.” Well, there’s a lot of ‘LED washing’ going on,” Mor said.
Cunningham agreed: “Skepticism is a barrier right now for LEDs because there’s a lot of junk on the market. Poor performance doesn’t help build adoption. The standard advice has been stick with the top manufacturers, but there are also a lot of smaller names providing quality products.”
Mor said there are red flags electrical contractors should note to avoid purchasing bad product.
“When approached by a LED sales rep, always ask for an independent, third-party test report of their product. Is there a cited LM79 test? If the company only has product in the 6,500K range, but nothing in say the 3,000 to 5,000 range, I’d stay away. If they can’t offer a true five-year warranty, that tells me they haven’t been in business that long.”
For Mor, the best guide to viable and commercially available LED lighting is the free online New Generation Luminaires (NGL) annual catalog. Located at www.ngldc.org, the site also features a useful “required documents” (www.ngldc.org/10/required_documents.stm) used as a qualifier for NGL’s annual SSL competition. Mor said this guide will help contractors determine the quality players from the “LED washers.”
NGL’s mission is to “recognize and promote excellence in the design of energy-efficient LED commercial lighting luminaires.” The 2010 SSL design winners are now listed. Out of 33 winners, this year’s “Best in Class” are the “fraqtir” linear concealed LED luminaire cove lighting fixture from the Lighting Quotient; the eW Burst Powercore facade lighting fixture by Philips Color Kinetics; the Equo LED desk lamp task lighting fixture by Koncept Technologies Inc.; and the NanoLED recessed accent lighting from USAI.
“If your goal is to lower maintenance costs or increase energy efficiency, LEDs are a good choice,” Mor said. “Costs are coming down but can still be high. You decide where you want to spend your money within the project. Remember, LED fixtures are a system that needs heat sink, a driver, housing and so forth. Though driver standardization has been slow, it’s coming and will make the digital leap.”
“Look beyond the idea that initial cost is everything,” Cunningham said. “It can be a barrier. Think about ‘total cost’ by factoring in maintenance and energy usage. LEDs are different. A new LED replacement bulb has an electronic appliance that is digital. That’s an important distinction and a real lighting revolution.”
GAVIN is the owner of Gavo Communications, a marketing services firm serving the construction, landscaping and related design industries. He can be reached at firstname.lastname@example.org.