Are required for public buildings and those occupied by public authorities which have a total floor area of 1,000m2 (GIA) and provide a public service to a large number of persons and therefore frequently attended by those people (eg hospital, community hall, school, government or local authority building).  As of the 1st October 2008 all public buildings will require a DEC.

Introduced as law, it is the responsibility of the public authority or relevant institution to display a DEC in each of their buildings and have in their possession a valid Advisory Report for each, which conveys recommendations to improve energy performance.A DEC shows the energy performance of a building based on actual  energy consumption as recorded annually over periods up to the last three years. 

The format of the DEC is likely to be A3 in size. 

 The Operational Rating is a numerical indicator of the actual annual carbon dioxide emissions from the building. This Rating is shown on a scale from A to G, where A is the lowest (best) and G is the highest (worst).  Property managers affected by this law will need to have annual energy meter readings and are advised to start collecting meter readings now to ensure they have sufficient data ready for the 1st October 2008 (date at which DEC's will need to be displayed).The Advisory Report will contain recommendations for improving the energy performance of the building. A DEC is valid for 12 months and needs to be updated annually. The accompanying Advisory Report is valid for 7 years.