Only buildings occupied or part occupied either by a public authority or an institution, that provides a public service, and expect to be visited by the public to a large number of persons and who are therefore frequently visited by those persons, and with a total useful floor area greater than 1000m² are affected by this legislation.

Where a building is partly occupied by a public authority or a relevant institution, the authority or institution is responsible for displaying a DEC and having a valid advisory report. A Display Energy Certificate shows the energy performance of a building based on actual energy consumption as recorded annually over periods up to the last three years. DECs need to be updated each year.