For controllability and energy savings in frequently switched applications,Universal Lighting Technologies has introduced the new ULTim8 Programmed Start Series of T8 linear fluorescent ballasts, designed to simplify compliance with legislative and code requirements that call for controllable lighting technologies such as occupancy sensors.
Featuring parallel lamp operation and ultra fast start times (<700 milliseconds), the new ULTim8 Programmed Start Series is engineered to reduce maintenance costs and extend lamp life in applications where lamps are being turned on and off throughout the day, whether manually or via lighting controls.
In addition, these ballasts are part of the NEMA Premium Electronic Ballast Program that identifies the most energy-efficient T8 fluorescent ballasts on the market today. This new addition to the ULTim8 High Efficiency ballast family includes 2-, 3-, and 4-lamp models with both 0.88 (HE) and 0.71(EL) ballast factor options available.
Monday, January 23, 2012
Tuesday, January 17, 2012
Illuminating Engineering Society (IES) 2011 Progress Report
The Illuminating Engineering Society of North America (IES) has published the 2011 Progress Report. (A .pdf link to the complete report at the bottom of this blog).
Each year, the IES Progress Committee offers manufacturers the opportunity to submit significant product developments and improvements to the lighting industry through the IES Progress Report. The mission of the Progress Committee is to keep in touch with developments in the art and science of lighting throughout the world and prepare a yearly report of achievements for the Society. Acceptance in the Progress Report is based on an impartial judging process used by the committee to evaluate each submission on its uniqueness, innovation and significance to the lighting industry.
Of the 261 submittals for 2011, 156 were accepted into the Report. Submissions were made in the following categories: Light Sources, Luminaires, Materials, Power Supplies, Accessories, Research, Publications, and Design Tools. The entries in the Report include a product photo, product name, essential features why it was selected and a contact for more information.
http://www.ies.org/PDF/ProgressReport/PR.pdf
Each year, the IES Progress Committee offers manufacturers the opportunity to submit significant product developments and improvements to the lighting industry through the IES Progress Report. The mission of the Progress Committee is to keep in touch with developments in the art and science of lighting throughout the world and prepare a yearly report of achievements for the Society. Acceptance in the Progress Report is based on an impartial judging process used by the committee to evaluate each submission on its uniqueness, innovation and significance to the lighting industry.
Of the 261 submittals for 2011, 156 were accepted into the Report. Submissions were made in the following categories: Light Sources, Luminaires, Materials, Power Supplies, Accessories, Research, Publications, and Design Tools. The entries in the Report include a product photo, product name, essential features why it was selected and a contact for more information.
http://www.ies.org/PDF/ProgressReport/PR.pdf
Friday, December 16, 2011
Dept of Energy's Jim Brodrick on Round 13 of CALiPER Product Testing
from www.lightnowblog.com
Results of the latest round of CALiPER testing were released recently, and as usual they can tell us a thing or two about the current state of solid-state lighting. As you may know, DOE’s CALiPER program supports testing of a wide array of SSL products available for general illumination, and publishes the results in summary and detailed reports, as well as a searchable database that allows side-by-side comparisons with previous rounds and benchmark products. CALiPER Round 13 focused on three types of LED luminaires for commercial and industrial applications: high-bay luminaires, wallpacks, and 2′x2′ troffers.
One thing it shows is that even in commercial lighting applications, which require high levels of light output and carefully designed light distribution, SSL luminaires are now clearly able to compete on a level playing field with traditional products. Most of the indicators from CALiPER Round 13 shed a positive light on the LED products in these categories, underscoring the fact that obtaining photometric data, understanding how it relates to the needs of the application in question, and comparing SSL and conventional options carefully are key to choosing the right products.
Round 13 shows that the average luminaire efficacy of products continues to increase, and color quality continues to improve. The average luminaire efficacy of the LED products tested in Round 13 was more than 60 lm/W, and most of them met or exceeded the efficacy of the traditional benchmark products tested. And while there were still some LED products that didn’t perform well, particularly with regard to light distribution, there was significantly less variation in product performance than in previous rounds, and a majority were found to meet or exceed manufacturer performance claims. Many of the products tested are taking advantage of the inherent strengths of SSL to achieve uniform light distribution similar to that of conventional luminaires, and in some cases are even improving on the uniformity of distribution.
Of special interest in Round 13 were the 2′x2′ troffers. These were all integral luminaires, with SSL technology designed into the product as a whole in order to take full advantage of it – quite a different animal indeed from the LED products that are designed to simply replace the 4′ linear fluorescent lamps used in 2′x4′ troffers. While those LED linear replacement lamps still fall short of their fluorescent counterparts in terms of light output and distribution, the LED 2′x2′ troffers tested in Round 13 fared much better, with some of them meeting the specifications developed by the DOE Commercial Building Energy Alliances and the DesignLights Consortium, a collaborative of utility and regional energy efficiency organizations.
Despite improvements, Round 13 shows that accurate reporting and product literature are still concerns – not only for LED lighting products, but also for their benchmark counterparts. In all cases, but especially for luminaires, it’s important to know which version of a product the photometric data applies to, and not to assume that other versions of the product perform similarly. The products that were found to have accurate manufacturer claims – which were in the majority – tended to include detailed photometric performance specifications that referenced LM-79 and avoided the use of equivalency statements. Products that omitted this detailed photometric data and made vague equivalency claims tended to fall short of expectations. What’s more, although only a portion of the products carried equivalency claims, most of those claims were found to be misleading or false, which means that buyers and specifiers should examine and understand photometric performance of both the LED products and conventional luminaires that they may be replacing, rather than rely on equivalency statements in product literature. A new DOE Technology Fact Sheet, “Establishing LED Equivalency,” offers guidance on understanding SSL equivalency claims.
Results of the latest round of CALiPER testing were released recently, and as usual they can tell us a thing or two about the current state of solid-state lighting. As you may know, DOE’s CALiPER program supports testing of a wide array of SSL products available for general illumination, and publishes the results in summary and detailed reports, as well as a searchable database that allows side-by-side comparisons with previous rounds and benchmark products. CALiPER Round 13 focused on three types of LED luminaires for commercial and industrial applications: high-bay luminaires, wallpacks, and 2′x2′ troffers.
One thing it shows is that even in commercial lighting applications, which require high levels of light output and carefully designed light distribution, SSL luminaires are now clearly able to compete on a level playing field with traditional products. Most of the indicators from CALiPER Round 13 shed a positive light on the LED products in these categories, underscoring the fact that obtaining photometric data, understanding how it relates to the needs of the application in question, and comparing SSL and conventional options carefully are key to choosing the right products.
Round 13 shows that the average luminaire efficacy of products continues to increase, and color quality continues to improve. The average luminaire efficacy of the LED products tested in Round 13 was more than 60 lm/W, and most of them met or exceeded the efficacy of the traditional benchmark products tested. And while there were still some LED products that didn’t perform well, particularly with regard to light distribution, there was significantly less variation in product performance than in previous rounds, and a majority were found to meet or exceed manufacturer performance claims. Many of the products tested are taking advantage of the inherent strengths of SSL to achieve uniform light distribution similar to that of conventional luminaires, and in some cases are even improving on the uniformity of distribution.
Of special interest in Round 13 were the 2′x2′ troffers. These were all integral luminaires, with SSL technology designed into the product as a whole in order to take full advantage of it – quite a different animal indeed from the LED products that are designed to simply replace the 4′ linear fluorescent lamps used in 2′x4′ troffers. While those LED linear replacement lamps still fall short of their fluorescent counterparts in terms of light output and distribution, the LED 2′x2′ troffers tested in Round 13 fared much better, with some of them meeting the specifications developed by the DOE Commercial Building Energy Alliances and the DesignLights Consortium, a collaborative of utility and regional energy efficiency organizations.
Despite improvements, Round 13 shows that accurate reporting and product literature are still concerns – not only for LED lighting products, but also for their benchmark counterparts. In all cases, but especially for luminaires, it’s important to know which version of a product the photometric data applies to, and not to assume that other versions of the product perform similarly. The products that were found to have accurate manufacturer claims – which were in the majority – tended to include detailed photometric performance specifications that referenced LM-79 and avoided the use of equivalency statements. Products that omitted this detailed photometric data and made vague equivalency claims tended to fall short of expectations. What’s more, although only a portion of the products carried equivalency claims, most of those claims were found to be misleading or false, which means that buyers and specifiers should examine and understand photometric performance of both the LED products and conventional luminaires that they may be replacing, rather than rely on equivalency statements in product literature. A new DOE Technology Fact Sheet, “Establishing LED Equivalency,” offers guidance on understanding SSL equivalency claims.
Monday, December 5, 2011
Trust, but verify: Reducing Risk Prior to LED Implementation
Copied from: http://www.creeledrevolution.com/blog/2011/12/05/trust-but-verify-reducing-risk-prior-to-led-implementation/
Those old enough to remember the 1980s may recall then President Ronald Reagan’s, “Trust, but verify” messaging as part of the United State’s Cold War negotiations with the former Soviet Union. While evaluating LED luminaires may not seem as important as dealing with a nuclear arms race, the same “Trust, but verify” philosophy should be used to reduce risk prior to any large scale implementation of LED products.
But what should you verify? To better limit risk it’s important to understand where risk resides. Some typical questions could include:
• How do I know I’ll get the necessary sustained light levels over the duration of my application?
• How do I know that the luminaire mounting is strong enough to withstand vibration over time?
• How do I know the luminaire and its paint finish are durable enough to resist corrosion?
It’s important to understand the difference between specifying product features versus specifying product performance. Specific product features may imply performance, but by themselves fall short of ensuring any specific level of performance. For example, a street light luminaire that advertises a product feature utilizing four mounting bolts, instead of two, may imply a certain level of increased performance. For instance, it may imply resistance to conditions such as vibration. But without credible performance data that specifically addresses vibration resistance, no assumption regarding a product’s resistance to vibration should be made. Specifying product performance removes product features from the specification and puts the focus on what actually reduces risk, some level of product performance.
Lets get back to the questions. Would the level of risk be more greatly reduced by pointing to either product specific features or credible performance data? Well if the movie Jerry Maguire was about a great lighting designer, he would have probably shouted, “Show Me the Data!” There are relevant standards in place that can be referenced to quantify levels of durability for the three questions above and more. Once the necessary performance level is determined and specified, potential suppliers should verify their ability to provide certain levels of performance with credible data so as to reduce risk.
But, what about product warranties – they minimize risk, right? Although warranties are designed to reduce risk, warranties also present certain risks as well. The first risk is based on the strength and credibility of the company offering the warranty in the first place. Two nearly identical five-year warranties may seem equal at first glance, but if there is a high degree of uncertainty that one of the two companies may even survive for five years, it’s unlikely these two warranties would be viewed as equals. Overall product reliability is another factor to consider when determining the potential strength or value of a warranty. Companies with proven performance are probably less likely to experience catastrophic failures on a scale that may jeopardize their ability to honor warranty claims compared to new companies entering the market.
So the goal to managing risk shouldn’t be left solely to a good warranty. Even the best warranties do not eliminate risk, since associated costs may be incurred should warranty claims need to be made. Therefore, specifying performance during the product selection process is the best way to minimize risk. Remember, “Trust, but verify.”
Those old enough to remember the 1980s may recall then President Ronald Reagan’s, “Trust, but verify” messaging as part of the United State’s Cold War negotiations with the former Soviet Union. While evaluating LED luminaires may not seem as important as dealing with a nuclear arms race, the same “Trust, but verify” philosophy should be used to reduce risk prior to any large scale implementation of LED products.
But what should you verify? To better limit risk it’s important to understand where risk resides. Some typical questions could include:
• How do I know I’ll get the necessary sustained light levels over the duration of my application?
• How do I know that the luminaire mounting is strong enough to withstand vibration over time?
• How do I know the luminaire and its paint finish are durable enough to resist corrosion?
It’s important to understand the difference between specifying product features versus specifying product performance. Specific product features may imply performance, but by themselves fall short of ensuring any specific level of performance. For example, a street light luminaire that advertises a product feature utilizing four mounting bolts, instead of two, may imply a certain level of increased performance. For instance, it may imply resistance to conditions such as vibration. But without credible performance data that specifically addresses vibration resistance, no assumption regarding a product’s resistance to vibration should be made. Specifying product performance removes product features from the specification and puts the focus on what actually reduces risk, some level of product performance.
Lets get back to the questions. Would the level of risk be more greatly reduced by pointing to either product specific features or credible performance data? Well if the movie Jerry Maguire was about a great lighting designer, he would have probably shouted, “Show Me the Data!” There are relevant standards in place that can be referenced to quantify levels of durability for the three questions above and more. Once the necessary performance level is determined and specified, potential suppliers should verify their ability to provide certain levels of performance with credible data so as to reduce risk.
But, what about product warranties – they minimize risk, right? Although warranties are designed to reduce risk, warranties also present certain risks as well. The first risk is based on the strength and credibility of the company offering the warranty in the first place. Two nearly identical five-year warranties may seem equal at first glance, but if there is a high degree of uncertainty that one of the two companies may even survive for five years, it’s unlikely these two warranties would be viewed as equals. Overall product reliability is another factor to consider when determining the potential strength or value of a warranty. Companies with proven performance are probably less likely to experience catastrophic failures on a scale that may jeopardize their ability to honor warranty claims compared to new companies entering the market.
So the goal to managing risk shouldn’t be left solely to a good warranty. Even the best warranties do not eliminate risk, since associated costs may be incurred should warranty claims need to be made. Therefore, specifying performance during the product selection process is the best way to minimize risk. Remember, “Trust, but verify.”
Tuesday, November 29, 2011
Luminaire 'Types' for parking lot lighting
Parking facility lighting luminaires are selected based on photometric distribution to specific areas of the lot surface.
Architectural luminaires blend with the total architectural design of the facility. Generally, they achieve efficient and uniform light distribution through reflectors and refractor lenses.
Pole-mounted luminaires can provide illumination at distances of two to two-and-a-half times the mounting height from the pole.
Post-top luminaires offer symmetrical and asymmetrical distribution, in either direct or indirect design. The mounting height is usually limited to no more than 26 feet.
Indirect type luminaires shield the light source from normal view, thus providing excellent glare control along with a good aesthetic appearance. These types of luminaires are used for parking lot lighting and hold lamps of 250W or greater, with a mounting height of 20 feet or more.
High mast systems have a mounting height of 66 feet or more and can cover a large area with a minimum number of poles. Suitable for nonresidential areas, the luminaires of a high mast system can provide symmetrical or asymmetrical distribution using refractors and/or reflectors, or the distribution can be totally indirect.
Roadway fixtures provide a wide range of symmetrical and asymmetrical distributions. The wall-mounted unit is applicable to a narrow area between buildings. The mounting height is usually no more than 26 feet. A wide variety of distribution types are available, generally divided in cutoff and semi-cutoff distribution design.
Architectural luminaires blend with the total architectural design of the facility. Generally, they achieve efficient and uniform light distribution through reflectors and refractor lenses.
Pole-mounted luminaires can provide illumination at distances of two to two-and-a-half times the mounting height from the pole.
Post-top luminaires offer symmetrical and asymmetrical distribution, in either direct or indirect design. The mounting height is usually limited to no more than 26 feet.
Indirect type luminaires shield the light source from normal view, thus providing excellent glare control along with a good aesthetic appearance. These types of luminaires are used for parking lot lighting and hold lamps of 250W or greater, with a mounting height of 20 feet or more.
High mast systems have a mounting height of 66 feet or more and can cover a large area with a minimum number of poles. Suitable for nonresidential areas, the luminaires of a high mast system can provide symmetrical or asymmetrical distribution using refractors and/or reflectors, or the distribution can be totally indirect.
Roadway fixtures provide a wide range of symmetrical and asymmetrical distributions. The wall-mounted unit is applicable to a narrow area between buildings. The mounting height is usually no more than 26 feet. A wide variety of distribution types are available, generally divided in cutoff and semi-cutoff distribution design.
Monday, November 14, 2011
Determining Light Loss Factor
From the Illuminating Engineering Society North America Lighting Handbook:
The light loss factor (LLF) is a fraction that represents the amount of light that will be lost due to things such as dirt on lamps, reduction of light output of a lamp over time, and similar factors. The following items are the individual components of the light loss factor.The total LLF is calculated by multiplying all the individual factors together. No factor should be ignored (set equal to 1) until investigations justify doing so. Lighting calculations should not be attempted until all light-loss factors are considered.
•Luminaire Ambient Temperature Factor
•Heat-extraction thermal factor
•Voltage-to-luminaire factor
•Ballast Factor
•Ballast-lamp photometric factor
•Equipment operating factor (H.I.D. only)
•Lamp-position (tilt) factor (H.I.D. only)
•Luminaire surface depreciation factor
•Lamp Lumen Depreciation
•Luminaire Dirt Depreciation
•Room Surface Dirt Depreciation
•Lamps Burnout Factor
The light loss factor (LLF) is a fraction that represents the amount of light that will be lost due to things such as dirt on lamps, reduction of light output of a lamp over time, and similar factors. The following items are the individual components of the light loss factor.The total LLF is calculated by multiplying all the individual factors together. No factor should be ignored (set equal to 1) until investigations justify doing so. Lighting calculations should not be attempted until all light-loss factors are considered.
•Luminaire Ambient Temperature Factor
•Heat-extraction thermal factor
•Voltage-to-luminaire factor
•Ballast Factor
•Ballast-lamp photometric factor
•Equipment operating factor (H.I.D. only)
•Lamp-position (tilt) factor (H.I.D. only)
•Luminaire surface depreciation factor
•Lamp Lumen Depreciation
•Luminaire Dirt Depreciation
•Room Surface Dirt Depreciation
•Lamps Burnout Factor
Monday, October 31, 2011
DOE seminar provides insight into what is succeeding and current challenges in LED lighting
In a session entitled "State of the industry and market forecast," Jim Brodrick, lighting program manager at the US Department of Energy (DOE), was the lead speaker at the LEDs 2011 conference in San Diego, CA. Brodrick described applications where LED-based solid-state lighting (SSL) is already succeeding as well as the technology shortcomings that are limiting the usage of LEDs in other applications.
Immediately Brodrick pinpointed the reason for the DOE's interest in SSL and investment in the technology. Quoting a DOE report issued earlier this year, Brodrick said that LEDs could yield 233 TWh in energy savings per year if LED lights totally replaced legacy sources in a short list of seven lighting applications – enough energy to power 19 million households.
Purpose-built luminairesBrodrick made a general statement about midway through his presentation that summed up the state of the SSL industry. About LED lighting products, he said, "If you design from a clean sheet of paper, you can come up with products that are really very good." He added that good designs must address all aspects of a luminaire including LED chips, optics, electronics, thermal management, and mechanical design.
It's easy to see where Brodrick's statement applies in readily available products. LED-based tubes intended as replacements for linear fluorescent lamps are still struggling to match the incumbent technology. In contrast, Brodrick said that several LED-based integral luminaires that are designed to replace tube-based troffer fixtures – as opposed to just replacing the tubes - can match or exceed the performance of fluorescent technology.
In general, Brodrick said that SSL is doing extremely well in recessed downlights, outdoor area lights, 2x2-ft troffers (not tube based) and refrigerated-case lights. The technology isn't doing nearly so well in small retrofit lamps including A lamps, the aforementioned linear-replacement segment, and cove lighting especially in cases where the legacy luminaires utilize fluorescent tubes.
LED retrofit lampsBrodrick spent more time discussing the problematic applications, acknowledging the continued interest in LED-based 4-ft tubes given the huge installed base of fluorescent troffers. He said the tubes are getting better and beginning to match the efficacy of fluorescents. But light output and distribution remain a problem as directional LEDs aren't a good match for fluorescent fixtures that were designed for a tube that radiates light around the entire cylinder.
Still, Brodrick said the LED tubes are beginning to work for some applications in terms of light output and cost. Specifically he said that the long life of LEDs make the tubes a fit for hard-to-reach applications. He also said the LED tubes are a good choice where vibration is present or in temperature extremes.
In the area of small replacement lamps including ubiquitous A lamps, Brodrick said that the technology is getting better although he said, "generally they don't match the output, color quality, and light distribution" of incandescent sources.
Brodrick described a recent DOE test of replacement lamps in which the agency visited eight big-box retail stores in the US and purchased 33 LED lamp products to test. He said that most failed to meet basic performance parameters that would satisfy consumers looking to replace incandescent or halogen lamps.
About the retailers, Brodrick said, "Some carry better products than others." The DOE hasn't identified the retailers in a publicly-available report, but Brodrick said the DOE had taken up the matter directly with the retailers to discuss the issue of consumer satisfaction with LED lamps.
Tackling roadblocksBrodrick concluded by discussing some items that the SSL industry needs to address across the entire application landscape. He said that despite the finalization of the TM-21 standard to project LED life, the industry continues to struggle to differentiate between lumen depreciation and luminaire life. We covered that very topic in the article " Understanding the difference between LED rated life and lumen-maintenance life" published in the October 2011 issue of LEDs Magazine. The DOE is working on the problem in conjunction with the Next Generation Lighting Industry Alliance and has published a paper focused on LED luminaire lifetime and reporting.
In terms of color quality, Brodrick said that the LED makers have made significant improvements and that tighter binning is a great benefit to luminaire makers. But he also said, "Color shifts over time are not well understood or predictable." He suggested more research is needed on the topic.
Brighter LEDs are also desirable of course. The DOE continues to raise lumen output and efficacy goals in its SSL Multi-Year Program Plan. In terms of efficacy, Brodrick said, "We're going for 258 lm/W." That's the goal for cool-white LEDs by 2020. For comparison, incandescent lamps are around 12 lm/W.
Tradeoffs were the final topic. In these relatively early days of the LED lighting industry, many conference talks have focused on optimizing every element of a luminaire including light output, color quality, efficacy, adaptive controls, and serviceability. Brodrick expects more affordable products to emerge as industry players identify what tradeoffs to make in specific applications.
Brodrick provided one example in the choice between modular-based approaches and what he calls an integrated luminaire that is purpose built for a single application. He said integrated luminaires typically have fewer components and lower assembly costs. He said modular designs are more convenient and can even be user serviceable but will also generally cost more.
Immediately Brodrick pinpointed the reason for the DOE's interest in SSL and investment in the technology. Quoting a DOE report issued earlier this year, Brodrick said that LEDs could yield 233 TWh in energy savings per year if LED lights totally replaced legacy sources in a short list of seven lighting applications – enough energy to power 19 million households.
Purpose-built luminairesBrodrick made a general statement about midway through his presentation that summed up the state of the SSL industry. About LED lighting products, he said, "If you design from a clean sheet of paper, you can come up with products that are really very good." He added that good designs must address all aspects of a luminaire including LED chips, optics, electronics, thermal management, and mechanical design.
It's easy to see where Brodrick's statement applies in readily available products. LED-based tubes intended as replacements for linear fluorescent lamps are still struggling to match the incumbent technology. In contrast, Brodrick said that several LED-based integral luminaires that are designed to replace tube-based troffer fixtures – as opposed to just replacing the tubes - can match or exceed the performance of fluorescent technology.
In general, Brodrick said that SSL is doing extremely well in recessed downlights, outdoor area lights, 2x2-ft troffers (not tube based) and refrigerated-case lights. The technology isn't doing nearly so well in small retrofit lamps including A lamps, the aforementioned linear-replacement segment, and cove lighting especially in cases where the legacy luminaires utilize fluorescent tubes.
LED retrofit lampsBrodrick spent more time discussing the problematic applications, acknowledging the continued interest in LED-based 4-ft tubes given the huge installed base of fluorescent troffers. He said the tubes are getting better and beginning to match the efficacy of fluorescents. But light output and distribution remain a problem as directional LEDs aren't a good match for fluorescent fixtures that were designed for a tube that radiates light around the entire cylinder.
Still, Brodrick said the LED tubes are beginning to work for some applications in terms of light output and cost. Specifically he said that the long life of LEDs make the tubes a fit for hard-to-reach applications. He also said the LED tubes are a good choice where vibration is present or in temperature extremes.
In the area of small replacement lamps including ubiquitous A lamps, Brodrick said that the technology is getting better although he said, "generally they don't match the output, color quality, and light distribution" of incandescent sources.
Brodrick described a recent DOE test of replacement lamps in which the agency visited eight big-box retail stores in the US and purchased 33 LED lamp products to test. He said that most failed to meet basic performance parameters that would satisfy consumers looking to replace incandescent or halogen lamps.
About the retailers, Brodrick said, "Some carry better products than others." The DOE hasn't identified the retailers in a publicly-available report, but Brodrick said the DOE had taken up the matter directly with the retailers to discuss the issue of consumer satisfaction with LED lamps.
Tackling roadblocksBrodrick concluded by discussing some items that the SSL industry needs to address across the entire application landscape. He said that despite the finalization of the TM-21 standard to project LED life, the industry continues to struggle to differentiate between lumen depreciation and luminaire life. We covered that very topic in the article " Understanding the difference between LED rated life and lumen-maintenance life" published in the October 2011 issue of LEDs Magazine. The DOE is working on the problem in conjunction with the Next Generation Lighting Industry Alliance and has published a paper focused on LED luminaire lifetime and reporting.
In terms of color quality, Brodrick said that the LED makers have made significant improvements and that tighter binning is a great benefit to luminaire makers. But he also said, "Color shifts over time are not well understood or predictable." He suggested more research is needed on the topic.
Brighter LEDs are also desirable of course. The DOE continues to raise lumen output and efficacy goals in its SSL Multi-Year Program Plan. In terms of efficacy, Brodrick said, "We're going for 258 lm/W." That's the goal for cool-white LEDs by 2020. For comparison, incandescent lamps are around 12 lm/W.
Tradeoffs were the final topic. In these relatively early days of the LED lighting industry, many conference talks have focused on optimizing every element of a luminaire including light output, color quality, efficacy, adaptive controls, and serviceability. Brodrick expects more affordable products to emerge as industry players identify what tradeoffs to make in specific applications.
Brodrick provided one example in the choice between modular-based approaches and what he calls an integrated luminaire that is purpose built for a single application. He said integrated luminaires typically have fewer components and lower assembly costs. He said modular designs are more convenient and can even be user serviceable but will also generally cost more.
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