by Jim Brodrick, U.S. Department of Energy
Results of the latest round of CALiPER testing were released recently, and as usual they’re worth noting because they help provide an indication of the current state of the solid-state lighting market – its strengths, weaknesses, and nuances. The U.S. Department of Energy’s (DOE) CALiPER program supports testing of a wide range of SSL products available for general illumination, and publishes the results in summary and detailed reports, as well as in a searchable database that allows side-by-side comparisons with previous rounds and benchmark products. Starting now, each CALiPER testing round focuses on a single product type or application.
CALiPER Round 14 focused on LED downlight retrofit units. Eleven such products, purchased between June and November 2011, were tested in a 6-inch insulation contact rated downlight housing mounted in a 24″x24″ insulated enclosure. Overall, their performance fit a relatively narrow profile. All of them emitted between 527 and 803 lumens and were roughly comparable in output to 60W-100W incandescent downlights or 13W-32W CFL downlights. But most had efficacies equal to or better than the system efficacy of a typical CFL downlight luminaire, with a range of 39-69 lm/W and an average of 49 lm/W – four to five times better than downlights using incandescent or halogen lamps.
As for color quality, it was generally good, with 10 of the 11 LED products meeting the ENERGY STAR criteria for color rendering index (CRI) of at least 80 and correlated color temperature within American National Standards Institute-defined tolerances. The measured CRIs were not quite as high as some previously tested LED downlight retrofit units, but would generally be acceptable for most applications.
Based on the performance range – which has stayed fairly consistent for several years now and is suitable for the intended application – it looks like LED downlight retrofit units are settling on a target market of replacing a 65W incandescent lamp or a CFL of less than 32W. One of the products tested in Round 14 has been on the market for at least three years, and its price has decreased by about 22 percent during that time. In general, the LED downlight retrofit units tested performed well and offer a viable option for specifiers of residential and light-commercial downlights, especially in retrofit situations. Most are best suited for applications that involve a normal ceiling height (8-10 feet).
With more than 800 million downlights installed in the U.S. – most of them using incandescent lamps – there’s potential for substantial energy savings by retrofitting with high-efficacy SSL products. Although the physical attributes of LED downlight retrofit units may limit their applicability, they also have several advantages. Because they’re designed to replace the existing trim and reflector, they can encompass a greater volume than LED replacement lamps, and thus they have more surface area for LED packages, as well as space for more sophisticated heat sinks. Improved thermal management capabilities, a larger emitting area, and more room for electronic components mean that these retrofit units have the potential for better performance than LED replacement lamps. Additionally, because the entire housing, mounting, and electrical connection may remain in place, retrofit downlight units can be a less expensive option compared to new integral LED downlights, especially when labor costs are considered.
However, based on the Round 14 findings, the lighting industry as a whole would benefit from the standardization of terms such as “retrofit,” “remodel,” and “replacement,” and product literature should be specific about the housings into which a retrofit product will fit. For example, with one “retrofit” LED downlight product that was ordered for this study, the supplied fixture was not designed to be mounted inside an existing downlight housing, but rather to use a supplied housing intended to fit through an existing hole in the ceiling!
LED downlight retrofit units were one of the earliest LED product types to compete well with conventional technologies, but today there are quite a few others. As the number of applications where SSL is a viable option continues to grow, buyers still need to be wary and to remember that not all products are created equal. DOE’s CALiPER reports provide a way to stay current with market trends and issues, to help ensure that the right decision is made.
