By BizLED Bureau
Feb 11, 2016: A report from the US Department of Energy (DOE) has published progress findings of LED-based MR16 lamps in last two years.
The DOE has released a report on ‘photometric testing of white-tunable LED luminaires’ of how many CCT test points are needed to measure operational characterization of such products. With changing time and technology, performance of heavy halogen lamps fare better than solid-state lighting (SSL) alternatives though newer products with improved colour rendering are available in market.
A report by DOE about MR16-centric Caliper was released in January of 2014. The previous report highlighted the fact that lamp manufacturers weren’t able to match the performance of 50W halogen products and much has not changed since then. This new report hints that they are better LED alternatives to 20W and 35W halogens but they still cannot outshine 50W MR16 lamps. The 50W products that are most commonly used due to their peak performance
Mean efficacy has gone from 54 lm/W to 61 lm/W in last two years, but that performance ramp is more shallow than in unidirectional and larger-form-factor directional lamps. DOE further stated that no available products are meeting Energy Star requirements for any angle for center beam candle power (CBCP). The CRI and CCT specs do comply with Energy Star requirements.
US Department of Energy publishes critical report for LED MR16 lamps
There can be many reasons for the technology stagnation in MR16 SSL products. The small form factor makes integrating the driver, LED sources, thermal elements, and optics a difficult challenge. There is far more incentive for companies to point on other LED-lamp sectors such as LED-based T8 tubes where the SSL alternative must challenge the an energy-efficient fluorescent incumbent. In the MR16 sector, the LED lamps are already delivering considerable energy savings even if CBCP trails the legacy halogen lamps.
MR16 lamps are vastly used in applications where excellent colour rendering is critical such as retail. Manufacturers supplying products for such applications focus on maximum CRI rather than on maximum energy savings in form of LED alternatives. DOE pointed that manufacturers would find the small-form-factor/thermal challenges easier to cross in targeting 50W halogen performance by putting pressure on efficacy levels. The entire report can be seen at DOE SSL website.
A report on tunable-white lighting technology was also published which focused on the need for luminaire makers to take detailed electrical and photometric measurements at 11 different CCT set points. These points are produced by a luminaire over the range of CCTs.
Use of 11 points would provide a comprehensive view of a tunable product performance; it would place a significant burden on luminaire manufacturers to perform such tests.
The important point to consider here is how tunable luminaires are designed and how light output and power consumption varies over the tunable range. With only 3 set points defined, the DOE found that lumen output errors could be as large as 10% relative to the 11-point characterization and the error in specified power draw is as high as 6%. That error ranges each drop to 3% when 6 points are tested.
The tests by DOE were performed on a small sample of five products and that other designs could draw different characteristics. The 6-point characterization would be sufficiently accurate for many SSL projects. Still, the tests were applied to tunable white lighting products that have linear tunable performance and not to dim-to-warm or full-color-tunable products.