DECs are designed to increase transparency about the energy efficiency of public buildings.
Where the building has a total useful floor area of between 250m² and 999m², the DEC and advisory report are valid for 10 years.
In order to produce the DEC the energy assessor needs to know the gross internal floor area of the building and the operating hours together with actual meter readings or consignment notes for all fuels used during the year of assessment.
It is, therefore, important for owners and occupiers of public buildings over 1,000m² to maintain good records of fuel used.
In the future the Government is expected to extend the requirement for DECs large privately owned buildings which the public have access to, such as supermarkets.