Status of solid-state lighting based on entries to the 2010 US DOE next generation luminaire competition

This paper analyzes the performance of 138 LED luminaires comprised of 95 indoor and 43 outdoor, all of which were within the judging phase of the 2010 U.S. Department of Energy Next Generation Luminaire™ (NGL) competition. The analyses focus on three areas derived from LM-79 and LM-80 test reports that were supplied by the manufacturers: energy efficiency, color, and long-term performance. Indoor recessed downlights and street lighting luminaires had the most entries. All luminaires employed phosphor-converted LED (PC-LED) packages or remote phosphor technology, reflecting the fact that these technologies now have better performance than color-mixed light emitting diodes (LEDs) for white-light applications. Comparisons of luminaire efficacy and luminous efficacy of radiation (LER) were made among the NGL 2010 submissions, luminaires with conventional light sources, and the expected performance of LED luminaires in the near future. 0-10V and reverse-phase control were the prominent dimming methods among the luminaires studied. High correlation (r = 0.98) was found between the CIE color rendering index (CRI) and NIST's Color Quality Scale (CQS). Compared to the luminaires recognized in 2009, a better balance was achieved between efficacy and CRI in 2010. The need to standardize the methods for evaluating LED products is discussed, including dimming performance, color-shift, long-term performance, and luminaire rated life. In person evaluation and mockups are recommended prior to specifying LED products.