Lighting policies that combine CRI & efficacy are misguiding


It is important for every government across the globe to be concerned about the waste in electric energy, and should look for ways to control it. As a bottom line, governments should encourage lower electric energy, which should be formally regulated by the governments.

However, lighting regulatory policies usually try to combine efficacy and color rendering elements, which is basically misguiding. Some policies are even found to be flawed. These policies try to modify the efficacy guidelines with a color rendering index (CRI) requirement, which is important to ensure quality of lighting. Such policies that aim to have strict restrictions on light source luminous efficacy (lumens per watt) should not penalize color quality.

Regulatory policies should not use CRI…

CRI is a calculation that compares the chromaticities of color chips lighted by a source with its chromaticities. The greater the chromaticity shift, the lower the CRI. But with lower CRI the color quality of illumination will not be able to satisfy the users.

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But on the other hand, higher CRI do not necessarily mean better color quality. Going by this theory, the policies should not use CRI as a patch to luminous efficacy requirements that ensures that light sources like LEDs will provide all the benefits of color quality.

Here the problem is not replacing one color quality patch with another, (example GAI). Rather, the solution should be to give a new dimension to the existing definition of luminous efficacy that is based on lumens per watt.

What can be the solution

Rather than adding color quality patches to photopic luminous efficacy requirements, the definition of the luminous efficiency should change, and include all photoreceptors found in human retina. The universal luminous efficiency function, U(λ) is a more accurate representation of the spectral sensitivity of human vision, so using it for defining the lumen in luminous efficacy would be more sensible.