DEC – for public buildings

Display Energy Certificates are a legal requirement for buildings that meet the following criteria:

They are at least partially occupied by a public service organization such as a school, NHS, council, leisure centre or Town Hall if the occupied area is in excess of 250sqm and It’s frequently visited by any members of the public.

The aim of Display Energy Certificates is to establish how energy efficient the UKs public buildings are and to give guidance as to how this can be improved.

DECs rate the actual or operational energy performance of a building against established benchmarks and take into consideration the ways in which occupants use the building.


Many locations such as schools have multiple buildings within the premises that are not connected. Each building over 250sqm will require its own certificate and often discounted prices are made available in these circumstances.


DECs for buildings between 250m2 - 1000m2 have a 10 year validity and DECs for building over 1000m2 have a validity of 1 year.

The operational rating on a DEC illustrates how efficiently the building is using energy. To calculate this rating a DEC Assessor will require information on the:

* type of building under assessment.

* total floor area of the building.

* annual energy use of the building (gas, electricity etc).

* methods used to heat and cool the building.

Some newer buildings will have this information to hand, especially if the facilities managers have been maintaining a log book or operations and maintenance manuals (O&M); but often, this information will need to be collected from a variety of documents held with separate departments within the organization.