The lighting power density or LPD is the lighting load in watts/sq ft (or watts/square meter). If the building has a plenum, it is important to know how much of this load is delivered to the space and the plenum. Lights consume electricity, and are a source of sensible load
Example:
The lighting power density was 1.2 watts/square foot, but when updating to new efficient lights, the new LPD was .7 watts/square foot