Understanding Lighting Colors and Light Output
"Warm," Cool," Daylight," etc.
Yellowish white light, reminding people of a fireplace, is called "warm" while bluish white light is
called "cool." These are based on associations with these colors. "Daylight" is supposed to
mimic light coming in from a window. These are crude, but useful classifications. However, we
can have differing degrees of "cool" and "warm": and therefore we need a quantitative measure,
the Correlated Color Temperature, described below.
Correlated Color Temperature (CCT) measured in Kelvins (K)
Correlated Color Temperature (measured in Kelvins)-or simply Color Temperature-is a scientific
scale to describe how "warm" or how "cool" the light source is. It is based on the color of light
emitted by an incandescent source. As a piece of metal (a theoretical Blackbody) is heated, it
changes color from reddish to orange to yellowish to white to bluish-white. The color of light
emitted by an incandescent object depends only on the temperature. We can use this scale to
describe the color of a light source by its "Color Temperature."