Efforts to replace the old and limited color rendering index (CRI) as the preferred way to convey information about a light source’s ability to correctly render color have led to proposed alternatives, the most ambitious of which is the 2015 Illuminating Engineering Society (IES) Technical Memorandum 30 (TM-30-15).
Most in the industry agree CRI is inadequate, but whether or not TM-30-15 is an appropriate replacement is still an open debate. The National Lighting Bureau (NLB), Shepherdstown, W.Va., put the debate on display in a panel discussion featuring three respected lighting industry experts at its annual meeting and recently released a video of that panel. Mark Lien of Osram Sylvania, Kevin Houser of Penn State University and Mark Rea of the Lighting Research Center at Rensselaer Polytechnic went round and round with their assessments of TM-30’s features and shortcomings.
Houser sees TM-30 as a significant step forward that lighting designers, manufacturers, and researchers can use now to improve lighting-system specification, light-source spectral design, and research on color perceptions.
Rea said he was “let down” by the proposed standard because the metrics have not yet been validated. As such, he said, it is not clear that the proposed metrics substantially reduce uncertainty about what constitutes good color rendering.
Lien said that with proper education the more complex TM-30 could be a help to engineers and other specifiers, but doubted that the rest of the lighting industry would be motivated to learn the intricacies of its measurements. While lighting specifiers will be motivated to learn and use improved color metrics, he said, that’s not likely to be the case for most electrical distributors, electrical contractors, interior designers, architects, and others for whom lighting is just one of many indoor and outdoor systems they have to deal with.