In energy modeling, Lighting Power Density (LPD) refers to what?

• A. The total annual building energy use.
• B. The amount of electrical power used for lighting per square foot; lower LPD reduces energy consumption.
• C. The color temperature of lighting.
• D. The cost of lighting per square foot.

Answer: (B)

LPD is the amount of electrical power used for lighting per unit area, expressed as watts per square foot (or watts per square meter). In energy modeling, this load-density metric captures how much lighting power the building uses for each square foot of space. Lowering LPD reduces the overall lighting energy, since you’re shrinking the instantaneous power drawn by lighting systems.

It’s different from total annual building energy use, which sums all energy across systems over time. It’s also not about color temperature (which describes the light’s color) or about lighting cost per area (which is an economic measure, not a load metric).