Have you ever put on a shirt in your closet only to notice it doesn’t match your slacks when you step outside?  How about walking into a doctor’s examination room….does it often feel cold and sterile?  These color qualities of light play a significant role in lighting design and are important to note when selecting CFLs.

Color quality is measured with two metrics: Correlated Color Temperature (CCT) and Color Rendering Index (CRI).  We often perceive the color quality of light by saying the light is warm and inviting or cool and sterile.  How we measure that warmth is through CCT or color temperature, labeled in degrees Kelvin (K).  Incandescent lights have a CCT of 2700K which is considered warm white.  Most lighting manufacturers will label their products as warm white, white, cool white or daylight as an intuitive guide. 

If you would like to match the color of your CFLs to the incandescent lights you have always used, be sure to select a CFL that’s labeled warm white.  For aging eyes and for task lights it may be a good idea to choose a higher temperature light (3000k-4100k range) labeled as white and cool white as these lights will enhance the contrast of objects being lit.  You may even choose daylight options for a very cool light (5000k – 6500k).

While color temperature measures the color of light coming out of the bulb, CRI is a measure of the affect the light has on the surfaces it strikes.  CRI measures how well the light source renders the colors of the objects being illuminated such as the shirt in your closet.  Incandescent lights have a perfect CRI rating of 100 while CFLs and LEDs are available in a range of CRI options. 

A CRI rating of 80 or higher is considered undetectable by the human eye and will be a safe bet for use inside your home.  ENERGY STAR qualified CFLs are required to have a minimum CRI of 80 or above.  Be sure to check all CFL and LED labels for a CRI rating of 80 or better.