A Display Energy Certificate is required by any organisation that has a usable internal area greater than 250m2 and is visited by the general public, and is wholly or partly publicly funded. The purpose is to illustrate how effectively the occupants and building is operated.

A DEC is created by an accredited assessor by firstly visiting the site to collect information on the age, structure, fabric, type of use, size and the energy using components such as heating, cooling, lighting etc. In addition to this fuel bills are needed such as gas, electric.

This information is then processed into government approved software programme called OrCALC and a certificate is produced.

The certificates are valid for 1 year and are accompanied by a recommendation report outlying areas of improvement which is valid for 7 years.