Measuring energy use in buildings

Energy use intensity (EUI) is the measurement used to size up a building's energy performance. It represents the energy consumed by a building relative to its size and is expressed in gigajoules per square metre per year.

A building's EUI is calculated as follows:

total energy consumed in one year (GJ) / total floor space of the building (m2)

For example, if an 8,000 m2 school consumed 7,000 GJ of energy, its EUI would be 0.88 GJ/m2. A similarly sized school that consumed 10,000 GJ of energy would have a higher EUI (1.25 GJ/m2) to reflect its higher energy use. Generally, a lower EUI signifies better energy performance.

Energy use intensity calculations

7,000 GJ/8 000 m2 = 0.88 GJ/m2/yr

10,000 GJ/8 000 m2 = 1.25 GJ/m2/yr