*Compact Florescent Bulbs and Color Temperature*
By: Spitfire
23 January 2006
Updated: 07 October 2010

Now that so many people are converting to compact florescent light bulbs to save energy and reduce costs of alternate energy systems, I thought it might be a good time to discuss bulb color temperature. Many people donít even know that bulbs are available with different color temperatures or what that means, but weíre Rubies so letís learn something new and get the best equipment for a particular task that we can.

All light falls somewhere on a "spectrum chart" made up of all colors from infrared to ultraviolet. In the middle of this chart is a small portion of light that is visible to the human eye. In the old days, the different colors in this spectrum were defined by "Apparent Color Temperature" but scientists have now standardized on the Kelvin temperature scale so that everyone agrees for instance what the color "blue" is. Weíre only interested in the portion of the Kelvin scale that ranges from 1,000 to 10,000 degrees. Remember, this "temperature" isnít like hot and very, very hot, itís just how visible light spectrum is measured. Different temperature bulbs are better suited to different uses. Letís see how some common compact florescent bulbs pan out.

Kelvin "Temperature"

Common Wording

Useful For

10,000 or 10K

Very high daylight bulb

Grow light for plants

6,000 or 6K


Simulating outside light

5,000 or 5K

Enhanced blues and reds

Detail work

4,000 or 4K

Neutral - colors show true

Below ground detail lighting

3,000 or 3K

Slightly enhanced colors

General work lighting, reading

2,700 or 2.7K

Warm lighting

General area lighting, reading


Since most of these bulbs cost about the same, you might as well get the ones that are best suited for what you need to use them for.

If you canít find what you need locally, Iíve had good success with these folks;


Update 07 October 2010:
Here's another excellent site that allows you to SEE a room using different color temperatures,

All materials at this site not otherwise credited are Copyright © 1996 - 2006 Trip Williams. All rights reserved. May be reproduced for personal use only. Use of any material contained herein is subject to stated terms or written permission.