EPCs for Commercial Buildings

5.1 What contributes to the energy performance of a building

Energy rating a building is a complex calculation that is based on a combination of factors. The key factors are:

• the type of construction of the building (including walls, roofs, floors and glazing)
• whether parts (zones) of the building are used for different purposes eg office, factory etc, and the occupancy profile for each zone
• heating, cooling, ventilation and hot water systems used
• lighting.

The energy performance of non-dwelling is shown as a CO² based index.

The CO² based rating a building receives depends on the energy used for space heating, water heating, ventilation and lighting, less any energy generated from energy generation technology installed in the building (such as solar water heating). The lower the number (on a scale of 0-150+), the lower the typical CO² emissions.

The rating is adjusted for the total useful floor area of a building (see glossary of terms for a full definition) so it is independent of size for a given type of building.