from Nicholas in Wauwatosa, WI:
#195
What gives CFLs their different color temperatures?
Light color is measured on a temperature scale referred to as Kelvin.
Great question! Different bulbs emit different colors of light, from warm tones to cool. This is known as color temperature, and is measured in degrees Kelvin (K). In general, the lower the Kelvin temperature, the warmer (more yellow) the light; the higher the Kelvin temperature, the cooler (bluer) the light. The majority of CFLs available in the market offer soft or warm white light (2700K–3000K), which is comparable to an incandescent bulb; but you can also choose "cooler" colors with whiter or bluer light. For a whiter light, look for bulbs marked 3500K–4100K. For bluer white light, look for bulbs marked 5000K–6500K.
When selecting a new CFL, it is a good idea to use the same color type as the incandescent you are replacing. When changing out multiple bulbs in one room, select ENERGY STAR qualified CFLs with the same color and the same manufacturer to help ensure more consistent light color. For more information, check out our Lighting fact sheet.
Published Monday, May 11, 2009