This is a legacy version of the WELL Building Standard. Please check the latest version here.

Color quality

Color quality is a function of the spectral output of a light source, the spectral absorbance/reflectance of an object, and the sensitivity of the eye’s cone photoreceptors to different wavelengths of light, which we perceive as color. Color quality impacts visual appeal and can either contribute to or detract from occupant comfort. Poor color quality can reduce visual acuity and the accurate rendering of illuminated objects. For instance, foods, human skin tones and plants may appear dull or unsaturated under lights that have low color quality metrics. Color rendering index (CRI) is a common way to measure color quality, capturing R1-R8 metrics. R9, while not always reported, is also included as part of this feature, as R9 values further take into consideration how we perceive the saturation of warmer hues.

Part 1: Color Rendering Index

To accurately portray colors in the space and enhance occupant comfort, all electric lights (except decorative fixtures, emergency lights and other special-purpose lighting) meet the following conditions:

a.80 Color Rendering Index Ra (CRI, average of R1 through R8) of 80 or higher.
b.80 Color Rendering Index R9 of 50 or higher.

Applicability Matrix

Core & Shell New & Existing Buildings New & Existing Interiors
Part 1: Color Rendering Index - O O
Commercial Kitchen Education Multifamily Residential Restaurant Retail
Part 1: Color Rendering Index O O O O O

Verification Methods Matrix

Letters of Assurance Annotated Documents On-Site Checks
PART 1 (Design)
Color Rendering Index

U.S. General Services Administration (GSA). Facilities Standards for the Public Buildings Service. March 2014, Washington, D.C., pp. 135-136.


The U.S. GSA's Facilities Standard for the Public Buildings Service Tier 1 High Performance rating requires CRI of 80 or higher.


The GSA's Facilities Standard for the Public Buildings Service Tier 2 High Performance requires a Color Rendering Index R9 of at least 50.