What is energy use intensity (EUI)?

• A. The total energy use of a building per year.
• B. The energy use per square meter or square foot per year; a measure of building energy performance.
• C. The energy usage of only lighting systems per year.
• D. The energy production per year from renewables.

Answer: (B)

Energy use intensity is about measuring energy use relative to building size. It expresses how much energy a building consumes per unit of floor area each year, usually in units like kWh per square meter per year or Btu per square foot per year. This normalization is essential because it lets you compare energy performance across buildings of different sizes and designs, focusing on efficiency rather than just total consumption. A lower EUI means a building is using energy more efficiently for its size.

This differs from the total energy a building uses in a year, which doesn’t account for how large the building is. It also isn’t about energy used by a single system like lighting, and it isn’t about energy produced by renewables. EUI is a benchmarking metric used to assess and track overall building energy performance.