Since June 2008, buildings occupied by public authorities need to have a Display Energy Certificate or DEC.
The rules apply to buildings where the total useful floor area exceeds 500m2 and which is frequently visited by the public.
You need to display the DEC in a prominent place, clearly visible to the public. You also need to have a valid advisory report which has recommendations for improving the energy efficiency of the building.
The regulations came into place on 9th January 2013.
For more information about DECs, visit the Government website.