In Lighting: Two Things You MUST Know About Color

a guest post by Lisa J. Reed, Lighting Designer

Lighting Two Things You Must Know About Color

I encounter confusion about color and light almost daily. It used to be so easy to buy a “light bulb…” Now you practically have to be a scientist. Let’s break it down into two simple parts. Think of these as how the light looks and how it feels.

  1. Color – of the light
    How the light looks:

    This one is the easiest to explain and understand. We’ve probably all noticed that some “white” light looks very yellow or orange and other “white” lights look almost blue. The color of light is measured in Kelvin, and is known as color temperature. If you like warm light, use a color temperature in the 2500 – 3000 Kelvin range. If you prefer whiter (cooler) light, use a color temperature in the 3500 – 4000 Kelvin range. Some people even prefer a bluer 5000K. For now, just pick the color you like, but don’t be confused about products labeled “daylight.” That just refers to a bluer color. It doesn’t mean that light will feel like daylight or that colors under that light will look like they do outside in the sun. For that, you need to know more about the spectrum of visible colors contained within the light.

    There is fascinating current research about how color temperatures affect people. It may be that certain colors are better for productivity while other colors are better for rest, and the variation of color temperature that one would encounter outdoors (with no electric light) over the course of a 24-hour period is best for human health. While fascinating, little of this research is conclusive, and until technology catches up that will allow color changing throughout the day and the proper wavelength within each white beam of light, it is mostly just a matter of personal preference.

  2. Color – of the object(s)
    How the light feels:
    This is where more people get confused. No matter what color the light is – whether it is a cool or warm color temperature – it can render objects poorly or it can render them well. It’s all about what spectrum of visible colors are contained within a particular light source.

    The most common metric used to measure this is CRI, or Color Rendering Index. This metric tells you how accurately a light source renders colors. How “true” the colors will appear under that light. Will a red apple look red, or will it be more of an orange-ish or pink-ish color? In theory, the perfect CRI is 100, so shoot for a high CRI for the best color rendering.

When discussing the color of a light source, be sure to clarify: Are you talking about color temperature or color rendering? There is a difference, and you need both to fully understand how a light source will look and feel.

Lisa J Reed photo - Lighting Blog

Lisa J. Reed has been attracted to lighting (like a moth to a flame) for 20+ years. She is the Founding Principal at Envision Lighting Design, LLC in St. Louis, where she designs, teaches, and writes about architectural lighting.


The opinions expressed by authors herein and those providing comments are theirs alone, and do not reflect the opinions of Graybar Electric Company, Inc. or any employee thereof. Graybar Electric Company, Inc. is not responsible for the accuracy of any of the information supplied by the authors or commenters. All the information on this website is published in good faith and for general information purpose only. Graybar Electric Company, Inc. does not make any warranties about the completeness, reliability and accuracy of this information. Any action you take upon the information you find on this website, is strictly at your own risk. Graybar Electric Company, Inc. will not be liable for any losses and/or damages in connection with the use of our website.