lighting power density

Lighting power density is the amount of electrical power used to illuminate a space, expressed in watts per unit of area. Its value results both from the lighting needs of a particular space as well as the efficiency of the lighting devices used in it.

The numerator is the power used for lighting and the denominator is the area being lit. The resulting density allows the lighting demand of differently sized spaces to be expressed on an area basis.

The value does not include a duration. Hours of lighting use affect the energy consumed, even when lighting power density remains unchanged.