A DEC must contain, by law, the following information:

1. the operational rating as determined by the government approved operational rating methodology
2. a reference value such as a current legal standard or benchmark

For buildings with a total useful floor area greater than 1000m² only, the DEC must also contain:

1. the operational ratings for the building expressed in any certificates displayed by the occupier during the last two years before the nominated date. In buildings where no historic energy consumption data are available, this information will not be complete until the third year of occupation after the introduction of DECs for that type of building as it will be derived from previous DECs

The DEC will also show the unique certificate reference number under which the DEC has been registered, the address of the building, the total useful floor area of the building, the name and address of the energy assessor, the name of their accreditation scheme and the date when the DEC was issued.