The U.S. Department of Energy’s CALiPER program has released Report 20.4, which is part of a series of investigations on LED PAR38 lamps. Report 20.4 focuses on lumen maintenance, chromaticity maintenance, and catastrophic failure in 32 of the Series 20 LED PAR38 lamps and eight benchmark lamps, which were monitored for nearly 14,000 hours at ambient temperatures between 44°C and 45°C. Among the findings:
* During the test period, 13 LED lamp samples failed catastrophically, although these failures came from only five of the 32 models of LED lamps, and five of them occurred in conjunction with a system power failure and/or the subsequent restart of the apparatus.
* On average, the lumen maintenance of the LED lamps was substantially better than the average for the other lamp technologies. After nearly 14,000 hours, the average lumen output for the non-catastrophically failed LED lamps was 94%, compared with 68% for the CFLs and 62% for the ceramic metal halide (all of the halogens failed, after typically reaching about 80% of initial output).
* While the average lumen maintenance for the LED lamps was very good, there was considerable variation from lamp model to lamp model. The worst-performing model had an average lumen maintenance of less than 75% at the final measurement point, whereas the best-performing lamps were above 100% of their initial output.
* On average, the LED lamps exhibited superior chromaticity maintenance compared to the benchmarks, but the average Δu’v’ of two of the LED lamp models exceeded the ENERGY STAR® limit of 0.007 and would likely be problematic in an application where color stability is important.
Given the continuous operation of the lamps in this investigation, the results should not be interpreted as indicative of a lamp’s performance in a typical environment. The report is best used to understand the variation in LED product performance, compare the robustness of LED lamps and benchmark conventional lamps, and understand the characteristics of lumen and chromaticity change.
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