The Future of LED Technology

We asked several experts to weigh in on the developments that LEDs have gone through in 2011 and to reveal what’s on the horizon for the new year.

Q. Walk us through the evolution of LEDs and what the lighting industry has seen this year.
A. “When LED lighting was first introduced to the market about 10 years ago, its use was limited to architectural and signage applications. Today, LEDs can be an economically viable solution for many general lighting applications,” says Cheryl Ford, applications marketing manager for OSRAM SYLVANIA.

“The advancements in LED lighting over the past five years have truly been remarkable, with the best LED luminaires delivering 70-90+ emitted lumens per watt,” she explains. “There are now high-quality LED luminaires for street, area, and landscape lighting; down lighting; track lighting; shelf and display lighting; decorative fixtures; even 2×2 luminaires that can replace fluorescent. The directional nature of LED sources allows for more of the lumens generated to be emitted from the luminaire compared to traditional light sources, making these luminaires extremely efficient. That said, it is important to choose luminaires that have the proper heat sinking for thermal management to ensure long life plus the right optics to control the light and minimize glare. The LED energy savings over traditional technologies varies from 20 to 80 percent depending on the application and luminaire choices.”

Daniel Rogers, LC, IES, LEED AP, ID+C of ICF International – a corporation that partners with government and commercial clients to deliver professional services and technology solutions in areas such as energy and the environment  – adds this perspective.  “For many architectural lighting applications, LEDs could be considered ‘square pegs’ the lighting industry has been trying to fit into the ‘round holes’ of traditional luminaires.  This past year has demonstrated manufacturers are finally developing ‘square holes’ – innovative, LED-specific luminaires configured to emphasize their strengths – that show great promise in many applications currently dominated by traditional light sources.”

Steve Parker, LC, president of SLV North America (a U.S.-based distributor of the German manufacturer) notes developments in LED technology are continually occurring. “Breakthroughs are being made weekly,’ he states. In addition to the LEDs themselves, Parker mentions that driver technology is steadily improving as well.

Jeff Cunius, engineering manager at Creative Systems Lighting (CSL ), another manufacturer that utilizes LEDs in its products, notes, “In the last year, we have seen increased light output as well as higher CRI LEDs on the market.”

Q. Will price continue to be a stumbling block for LEDs?
A. Cost has definitely been a challenge in 2011. “The staggering price increase and significantly limited supply of rare earth elements (used to make phosphors) will likely have a profound, albeit indirect, impact on the LED market,” Rogers explains.

“In 2011, manufacturers were forced to pass on some of this cost increase to consumers,” he says. “While CFL and linear fluorescent lamps experienced significant (and ongoing) price increases, LED prices remained largely unaffected. This is because, compared to fluorescent lamps, blue or short-wavelength LED systems require a tiny amount of phosphors to produce white light. LED system prices are coming down, but still remain higher than equivalent fluorescent systems for most architectural lighting applications. However, the shift in cost comparison ratio due to phosphor price should further accelerate market penetration of LEDs.”

Cunius mentions that CSL will be lowering the cost of the older LED technology and incorporating the newest technology into the same fixture and bring it to market at the same price that the old technology used to be.

Q. What should lighting designers look for in LED products?
A. “When evaluating LED luminaire options, decision-makers really need to examine the total cost of ownership and not the upfront cost,” Ford advises. “The energy and maintenance savings alone can often justify using LED lighting on a project. There are many utility rebates available for a variety of LED luminaires that would provide one- to three-year paybacks over using traditional lighting technologies. Most of the utility rebates are for ENERGY STAR-rated luminaires or luminaires approved by the Design Lights Consortium, which tests luminaires to the ENERGY STAR standards,” she notes.

In addition, Ford mentions that the lighting design community has concerns about the ease surrounding the upgrade and replacement of LED light engines in LED luminaires since most are now hard-wired into fixtures. Parker states that, in some cases, it’s possible that an LED light source can outlast the driver.

With such concerns being discussed in the industry, there are some places to turn for guidance. Both Parker and Ford point to the Zhaga Consortium as one source. Zhaga is an industry organization that is developing standard specifications for the interfaces for LED light engines that would allow for the interchangeability of LED light engines from many manufacturers. “The goal is to create standards for mechanical and electrical interfaces that provide standardized holders, heat sinks and/or luminaire requirements. This type of standard would definitely help to speed up the development and adoption of LED Lighting,” Ford says. “Obviously, these standards will not materialize overnight, but this is a big step in the right direction and a huge global effort.”

Standardization is indeed a key element for future growth that many in the lighting sector are waiting for. “Having standardization would benefit the industry greatly,” Parker affirms.

According to Rogers, there have been standard lighting measurement methods in place for LED products since 2008 as defined in two documents: IES LM-79-08 (for LED luminaires and integral LED lamps), and IES LM-80-08 (for LED packages, arrays, and modules).

“IES TM-21-11 was published this past summer and defines a specific method and exponential decay model for projecting long-term lumen maintenance of LEDs using data obtained when testing them per IES LM-80-08,” Rogers explains. “The ENERGY STAR Luminaires V1.1 final specification (which takes effect April 1, 2012) requires a TM-21 lumen maintenance life projection report for any commercial-grade LED luminaire claiming L70 lumen maintenance life greater than 35,000 hours.  Additionally, EPA is considering IES TM-21-11 as the basis for lumen maintenance projections for the upcoming ENERGY STAR Lamps V1.0 specification which should be finalized in spring 2012,” he adds.

“When evaluating luminaire performance, make sure to ask for the IES Standard LM-79 data to evaluate the photometrics of the luminaire and IES Standard LM-80 data to evaluate the lumen maintenance data for the LEDs used in the luminaire design to verify life ratings that are based on the point in time where the luminaire will have 70 percent of its initial lumens,” cautions Ford. “Most indoor luminaires typically have a rated life of 50,000 hours, but there are many street and area lighting luminaires with life ratings (L70) in the 70,000-100,000 hours range,” she states. “Underwriters Laboratories (UL) is also developing a safety standard for LED light sources and currently has an ‘Outline of Investigation for Light Emitting Diode Light Sources for Use in Lighting Products’ designated as UL8750 provides minimum safety requirements for SSL components, LED, LED arrays, power supplies and control circuitry and includes references to all applicable UL standards.

Another area of concern in the design community involves color consistency lamp-to-lamp and color stability over life. “These are being addressed with ‘hot binning’ of LED chips or the incorporation of intelligent active color control into the LED system to maintain the color within a three-step MacAdam ellipse,” Ford explains. “The loss of 30 percent of the rated lumens over the rated life is somewhat undesirable and requires over-lighting a space initially to ensure proper light levels over the life of the LED luminaire. However, the incorporation of intelligent controls built into a luminaire to maintain the lumens at a constant level throughout life can eliminate this problem.”

Q. What’s new in the retrofit market?
A.  “There are now premium LED PAR and A-lamps available with a 95+ color rendering index and a high R9 red component greater than 50 that should be used for color-critical applications,” Ford explains, adding, “ LED lamps typically are rated for 25,000 hours life, but some have 50,000 hours rated life (L70). LED replacement PAR lamps come in PAR16, PAR20, PAR30, PAR30LN and PAR38 configurations and there are now LED PAR lamps that can replace up to a 90-watt halogen.” Ford’s advice is to choose omni-directional LED A-line lamps to ensure similar light distribution to incandescent A-lamps. “There are LED A-lamps that can replace up to a 100-watt incandescent lamp,” she notes.

“Keep in mind that most of the available LED lamps on the market have an 80-85 color rendering index and that not all LED lamps are dimmable,” she cautions. “Even if the LED lamps are dimmable, make sure the lamps are used with compatible dimmers to ensure good dimming performance. It may require replacing dimmers in an existing installation. Right now LED MR16 lamp choices are limited and the best lamps available will replace up to a 35-watt halogen MR16. Color consistency from lamp to lamp continues to improve, but again not all products are alike.” Ford suggests selecting LED lamps that are ENERGY STAR-rated to make sure that they perform to the established minimum requirements for good performance.

Parker adds, “What I’d like to see in the industry is a standardized socket/receptacle mounting that would allow the LED to be replaced or upgraded as performance improves in the future.”

Q. What’s so special about OLEDs?
A.  Organic LED technology (OLED) development is ongoing for general lighting applications, but it’s not quite ready for prime time. “It’s currently more of niche product due to its high cost,” Ford explains. “However, organic LEDs do open up completely new possibilities for architects, lighting planners, and designers due to its thin, flat profile that can turn essentially any object, piece of furniture, wall, ceiling, window, and many other items into a light source. Even illuminating surfaces such as lit ceilings and partition walls are feasible with OLED.”

Rogers agrees that efficacy and light output will continue to improve, but notes, “OLEDs still have a long way to go to become a practical source for most architectural lighting applications. The exciting thing about OLEDs is that they can be manipulated and configured to create forms not possible with any other light source. How far OLED technology improves will determine whether it remains limited to decorative/signage applications or becomes a viable general lighting source.”

The performance of OLED panels today is approximately 45-50 lumens per watt, 3,000 lumens per square meter, with a 10,000-hour lifetime but is expected to be over 100 lumens per watt, 10,000  lumens per square meter, with a 50,000-hour lifetime by 2015, according to the U.S. Department of Energy (DOE) target goals.

“Performance improvements and lower costs to manufacture are needed before this technology becomes a mainstream product for general lighting applications, so mass adoption of this technology is not expected in the next couple of years. However, the adoption of LED luminaires will escalate between now and 2015,” Ford predicts.

Cunius points out that OLEDs are approximately double the cost of LEDs currently on the market, but they are not even close to being as efficient as LEDs. “Until the OLED efficiency is improved, CSL has no plans on using them in any future product lines,” he states.

Q. What’s ahead for 2012?
A. All of these experts agree that there will be increased efficacy, more LED fixtures with intelligent controls, and further development of OLEDs for general lighting applications.

Ford notes, “The best discrete LEDs available today are in the range of 120-150 lumens per watt and are projected to be over 200 lumens per watt according to the U.S. Department of Energy.”

Rogers also underscores the importance of control. “Lighting designers have long stressed that LEDs must respond consistently to lighting controls,” he explains. “LED manufacturers are finally listening and now luminaire manufacturers are hearing it from both sides. Therefore I expect 2012 will bring the increased availability of LED luminaires with integrated controls for occupancy sensing, dimming, and daylight harvesting.”

Parker would like to see manufacturers starting to create more fixtures for LED technology instead of only retrofitting them. This is something that SLV has been doing, along with retrofitting.  “We should embrace the advantages of LEDs and create entirely new fixtures that capitalize on the benefits,” he comments. “This might also mean that people may have to look at lighting fixtures differently. When electricity became commonplace, lighting fixtures were based on the familiar gas lantern shape. With LED light sources being so small, fixtures do not have to be as bulky. Therefore, fixtures and lamps don’t have to look the same as they always have.

All of our experts agree that the next few years are going to be very exciting indeed as efficiency is improved and costs go down. The lighting industry is about to be changed forever.

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