I recently had the opportunity to interview Steven Pyshos, Business Development Manager, Commercial Downlighting, Cooper Lighting Solutions, and Rebecca Hadley-Catter, Manager, SOURCE Lighting Education Center, 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?
Pyshos: Having knowledge of, access to and stocking lighting products with excellent color rendering is now more important than ever for distributors to support their customer’s needs.
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?
Hadley-Catter: CRI 80 is still acceptable for non-critical commercial applications and remains a good compromise between source efficiency and color rendering. The availability of LED sources with high color rendering and good efficiency has replaced tungsten-halogen. For that conversion to be successful CRI 90 is essential and many designers are using CRI 95 and higher to best render critical applications.
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?
Pyshos: Manufacturers were first to support TM-30 providing a more complete measurement of color performance. It can be a difficult change; measurement devices and software need to be updated. It was also necessary to devise new methods to transmit TM-30 data in both print and digital formats.The specification community is lagging adoption; not all manufacturers provide TM-30 data across all products.
DiLouie: What are the relative advantages of CRI and TM-30?
Hadley-Catter: CRI is well known; the design community is comfortable using to predict color performance on their projects. TM-30 is a more accurate measurement of color performance.
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?
Pyshos: While CRI is an easier color metric to understand it falls short of accurately communicating color performance of LED sources. No question learning the nuances of TM-30 will take effort, however, will benefit their selling efforts to discriminate between lighting products.
DiLouie: For the majority of 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+?
Hadley-Catter: Color rendering performance should be based on the application, not the measurement scheme. While both CRI + R9 and TM-30 Rf and Rg are useful tools, TM-30 is a more complete measurement of color performance.
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?
Pyshos: CRI has been used successfully as a selling tool to prescribe color performance for many years, high color rendering is an upsell. Additionally, meeting minimum color rendering performance is required by local codes, many manufacturers including Cooper Lighting Systems, note California Title 20 and 24 compliance on packaging and literature. ENERGY STAR® also prescribes minimum color rendering to earn their certification; ENERGY STAR® is often used to support rebate programs from local utilities.
For TM-30 to be used as a successful selling tool, additional industry adoption and education is needed. Additionally, the TM-30 color metrics require additional definition to be applied effectively for a given application.
DiLouie: What is the elevator pitch distributors should be using to differentiate themselves and convince customers that a more detailed approach to color rendering is important?
Hadley-Catter: Color rendering performance requirements must be well aligned to a given application and using a more predictive color measurement system will ensure the designer’s vision is realized.
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?
Pyshos: CRI measures color performance for 8-14 targets, LED manufacturers understand this and compound phosphors to excite those targets scoring well even with poor or inconsistent spectral power distribution. TM-30 measures color performance for 99 targets and reports both chromaticity (Rf) and saturation (Rg) yielding more accurate color measurements. More complex phosphors reduce direct blue contribution reducing efficiency and increasing cost.
DiLouie: How does TM-30 apply to tunable-white lighting products?
Pyshos: CRI and TM-30 can describe color performance at any point along the black body curve, however, does not describe the curve itself for a given white tuning product.
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?
Hadley-Catter: At this point, understanding spectral power distribution is the most helpful way to visualize melanopic lux.
DiLouie: If you could tell the entire electrical industry just one thing about color quality and LED lighting, what would it be?
Hadley-Catter: Embrace TM-30 color vector graphics, a great tool for visualizing color performance
DiLouie: Is there anything else you’d like to add about this topic?
Pyshos: TM-30 assumes delivered color performance where CRI is almost always source color performance. Since the luminaire’s optical system impacts color performance, the specification community should request delivered color performance data similar to delivered versus source lumens.
