U.S. Power Vision, LLC

From the Community of Manufacturing, Design and Contracting Teams of U.S. Power Vision, LLC

Fabulous Lighting Mave

www.USPowerVision.com • 1963 Park Avenue • Twin Lake, Michigan 49457 • RMotsch@USPowerVision.com

The Color Rendering Index (CRI) Scale

Dear Reader:

The quality of electric lighting is a matter of color, and the industry has broken it into 14 shades. When a fixture is rated, each of these shades is judged through a testing method designed to assess how close the respective shade mimics the color of sunlight, on a scale of 1 to 100, with 100 being the equivalent of pure sunlight.

While this algorithm has some shortcomings (see our edition dedicated to R9 and R13), it is currently the industry standard, so we’ll explain it here.

Notice from the illustration the 14 shades of color depicted.

This scale was developed in 1965, and is still in use today. Ultimately the ratings for the various shades are amalgamated into

an average, and typically this score, known as a fixture’s Color Rendering Index, or ‘CRI’, is posted somewhere on its spec sheet.

All LED fixtures enjoy a CRI of at least 70, and by and large, the vast majority are at or in excess of 80, so much so, in fact, that it’s becoming fairly rare for a fixture to be judged down in the 70s in today’s LED market. 80 is the new minimum, and generally speaking, is acceptable for virtually all areas of a manufacturing or food processing facility.

The exception might be for specific areas of production requiring a higher-quality light, i.e. testing or inspection areas where color is extremely important, or texture – and therefore contrast – plays into a decision-making process. Second, office areas might also lend themselves to CRIs of 90 or above, as hours of computer use can create fatigue, and higher quality technologies alleviate that.

Here’s the rub: in the industry’s wisdom the first 8 shades of color are all that’s included in the averaging formula for CRI. It was the developer’s view that this was all that was necessary, as fluorescent lighting didn’t include reds and yellows and skin tones anyway, so an assessment of the cooler colors was all that was necessary.

This is no longer the case, as one of the features of LED technology is in its ability to accurately illuminate the warmer tones found in life. R9 (red) and R13 (skin tones) are clearly important. See GE Lighting’s TriGain technology linked here.

U.S. Power is an industrial energy services company that specializes in the reduction of energy consumption across a broad array of manufacturing and food processing facilities located in Michigan, Ohio, Indiana, Illinois and Wisconsin. In addition, the company publishes a useful curation of lighting-oriented information from the marketplace, and consolidates it into this concise, twice per month letter known as The Fabulous Lighting Maven, distributed to Facilities Managers throughout the nation.

While the company prides itself in its diversity, it owns and operates a niche lighting contracting firm as well, known as U.S. Power Vision, LLC. With a core business in and around industrial LED lighting, it keeps itself and its clients at the cutting edge of illuminating technologies, all aimed at providing – from the eyes to the fingertips – exceptional illumination, superb control and intuitive simplicity.

The Maven publishes these pearls weekly, or more frequently if we feel like it, because we believe America is already great, and poised to be even greater if we commit to doing our part towards cooling the planet. Publisher Ron Motsch can be reached at (616) 570-9319.

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