A DEC and advisory report are required for buildings with a total useful floor area (see definitions at Annex B) over 250m2 that are occupied in whole or part by public authorities and frequently visited by the public. 

Only buildings, with a total useful floor area greater than 250m2, occupied by a public authority and frequently visited by the public are affected by this legislation.

Private organisations, including those that may share a building with a relevant institution, do not need to display a DEC, but may elect to do so on a voluntary basis.