Buildings requiring a Display Energy Certificate (DEC)
Public authorities, and institutions providing public services to a large number of persons, who occupy space in a building with a total useful floor area greater than 1000m2, must display a valid display energy certificate ("DEC") at all times and have a valid advisory report in their possession.
A DEC shows an operational rating which conveys the actual energy used by the building as opposed to an EPC which conveys an asset rating showing the intrinsic performance of the building.
Only public authorities or public institutions (those providing services traditionally associated with local or national government) occupying a building must display a DEC. Other private occupants of the same building are not required to display a DEC.
If the building is sold or let, it will additionally require an EPC. If the building has an EPC, the asset rating will need to be included on the DEC. Further guidance on DECs is available see: www.communities.gov.uk/epbd