R9: More Important Than CRI?
 R9 is a lighting metric concerning the color red. Photo by  Thomas Martinsen  on  Unsplash .

R9 is a lighting metric concerning the color red. Photo by Thomas Martinsen on Unsplash.

Like flicker, color is a widely-debated and often misunderstood topic among the lighting industry. In the past few years, we have seen the following changes regarding color:

  • TM-30-15, a new color metric from the Illuminating Engineering Society
  • California Title 24’s minimum 90 CRI requirement for residential buildings
  • A minimum R9 of 50 as an optimization for the WELL Building Standard and a requirement for residential buildings under Title 24

We can debate the merits of CRI all day, but in 2018, most LED and luminaire manufacturers do not provide any other color information on their datasheets. Since we’re a long way from a universal understanding and application of TM-30, I am going to focus on CRI and R9 today.

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Greg Yeutter