Color has always been a significant topic in lighting. It’s a complicated and nuanced issue that at its core is shaped by no fewer than eight key concepts: constancy, temperature, rendering, difference, appearance, shift and stability, colorfulness, and matching. The industry’s current primary color metric, the Color Rendering Index (CRI), isn’t perfect but it has served as the closest way of addressing the issue.
But with the introduction of LEDs, color has become even more important, and the industry has been looking for a way to establish a measurement system that better corresponds to the characteristics of LED light. In the mid-2000s, one attempt to address the problem was creation of the Color Quality Scale (CQS), but that never really took off. This past fall, a major step was made toward providing a more comprehensive way of evaluating color with the release of TM-30-15, IES Method for Evaluating Light Source Color Rendition. The new metric proposes 99 color-evaluation samples, as opposed to the much-smaller batch of 14 currently used by CRI. That said, this new system still has areas, such as the computation of the reference luminance and fidelity, where there is room for further clarification, notes Kevin Houser, professor of architectural engineering at Penn State University and one of TM-30’s authors. To help you better understand the new TM-30 color metric, Houser has set up a website where you can find more information: personal.psu.edu/kwh101/TM30/main.htm
The word is still out on TM-30. Some companies, such as Xicato and Soraa, have already started incorporating TM-30 data in their product spec sheets. Others, such as Philips, Osram, and GE Lighting, have voiced concerns, as has the Lighting Research Center in Troy, N.Y. To be sure, TM-30 will be one of the key buzzwords at Lightfair this year as the industry determines if this new metric will lead to a better way to evaluate color. •