A Display Energy Certificate and Advisory Report is required for any building occupied in whole or part by public authorities and frequently visited by the public where the floor area is greater than 250m2. The Certificate must be displayed in a prominent place clearly visible to the public.
They may also require Energy Performance Certificates if they have been recently constructed, modified, sold or leased.
DECs show the public how much energy a building uses and how energy efficient it is compared with other similar buildings. They are accompanied by advisory reports that list cost-effective measures to improve energy ratings.
For buildings with a total useful floor area of more than 1,000m², the DEC is valid for 12 months. The accompanying advisory report is valid for seven years. Where the building has a total useful floor area of between 250m² and 1000m², the DEC and advisory report are valid for 10 years.