I recently had the opportunity to interview Sally Lee, LC, Business Development & Special Projects, LEDVANCE, LLC on the topic of light + color, specifically looking at developments with TM-30. The interview is being used to write an article on this topic for tED Magazine’s July issue.
DiLouie: Why is color rendering an important factor for electrical distributors when selecting light sources?
Lee: Customers are hard to pin down and gain loyalty from. Winning lighting distributors always work to help them understand and use technology to meet their goals. Now the importance of lighting color can be discerned and specified, so customers can understand the value of it for their individual projects.
DiLouie: For years, the industry settled on a CRI of 80+ for commercial general lighting and 90+ for color-discerning applications. Why is that not enough in the LED era?
Lee: Commercial general lighting was 70+ CRI and 80+ CRI with linear fluorescent lamps and LED replacement lamps pushed everything up to 80+. In our modern era, while it still holds true that generally a higher CRI light source renders colors more accurately, the spectrum of LED lighting can vary so much based on what the product is being developed for.
DiLouie: IES-TM-30 turns five this year. How successful has the proposed metric been in becoming adopted by manufacturers in reporting and by specifiers in application?
Lee: And CRI turns 55 (Color Rendering Index CIE13.2-1965/1974)! Since early TM-30 training, I’ve look around for product information, and still haven’t seen much yet. Internally we began using it right away to help with the pragmatic concerns of designing and optimizing new LED products – along with efficacy, appearance, distribution/ intensity, and of course cost. It is so much better than CRI!
For specifiers out in the marketplace, later this year we expect adoption to accelerate as new DLC V5.1 requires the newest TM-30 spectral data (in addition to CRI). In context, designers still set goals after understanding the environment their client wants to create, but additional information about color accuracy will help identify the best light source(s). The math is sound, the reference-based approach is familiar, but it’s more comprehensive and improves transparency about color performance. Once the guard rails are off and it’s “Insta,” it will help guide where sources will fit best.
DiLouie: What are the relative advantages of CRI and TM-30?
Lee: When we started working with Ceramic Metal Halide (CMH) in the late 1990s – which had CRI of 82-85, they were compared to Halogen – which had CRI of 95-100. On paper, this did not seem too promising for color critical applications, but everyone just brushed past this CRI disparity once they visually evaluated both together, because the CMH was so compelling. It is not a new problem that CRI alone cannot account for modern light sources that realize better color performance. TM-30 unpacks color performance so we understand and communicate more clearly about light source color, in the context of individual design goals. It really seems overdue.
DiLouie: One advantage of CRI is it’s easy and simple, and TM-30 requires effort. Why should distributors invest time in learning TM-30, and what advantages does it provide them when selling lighting?
Lee: CRI has had an outsized influence. Two important advantages of a really good lighting distributor are trendsetting and influencing. Even customers who are hard to pin down and gain loyalty from look to them for solutions. Better data drives better decisions, and lighting distribution can manage to understand this new tool, and use TM-30 to get beyond product marketing to measurable differences that truly matter.
DiLouie: For most commercial general lighting applications, is it enough to simply modify CRI and add an R9 (saturated red) threshold, or update the 80+ requirement to 90+?
Lee: It is time for a Gen Z color specification platform, especially as we engage with better questions and better technology. The “best light” remains subjective, but there are a few extra dimensions within TM-30 we can grab a hold of.
DiLouie: How can color rendering in general be used as a selling tool by distributors? How can TM-30 be specifically used as a selling tool?
Lee: It’s a practical matter of nailing down color and selling it to a customer when there is a value. Anything that empowers communication is going to improve the project outcome.
DiLouie: What are the characteristics of LED products that TM-30 reveals as being superior in color quality, and what the overall advantages of disadvantages of these products versus other LED products? Are there performance tradeoffs, and if so, what are they?
Lee: It really seems like lighting efficiency is going to keep demanding the spotlight, because our culture sees lighting as a commodity and we are so cost driven. It is very good news overall that LED lighting installations have realized the LIFT from the broader spectrum and better color characteristics. Now that we have better guard rails in this new tool that is TM-30, we will realize even more benefits of improved lighting color as the attributes become more transparent.
DiLouie: How does TM-30 apply to tunable-white lighting products?
Lee: In design, we always choose the CCT (color temperature) first, then color rendition. If you’re going to use a dynamic CCT product, you’d need more than one TM-30, so be able to ask for what you know you’ll need in order to evaluate products.
DiLouie: As circadian-supportive lighting becomes more important in the future, how will CRI, TM-30, and spectral power distribution graphs work together to best support applications?
Lee: Leaders will design and manufacture products to specified standards, which will be driven by the design community and evidenced based design and appropriate test and measurement protocols. We support different metrics to appropriately guide product application decisions.
DiLouie: If you could tell the entire electrical industry just one thing about color quality and LED lighting, what would it be?
Lee: Expect something better.
DiLouie: Is there anything else you’d like to add about this topic?
Lee: I would love to experience a hands-on lighting workshop on the show floor at Lightfair where I could immerse myself in color booths and “try on” sources that are identified by both their CRI and Color Fidelity and Gamut!
