What is a Display Energy Certificate?

A display energy certificate (DEC) shows the energy performance of a building based on its actual annual energy consumption and the CO₂ emissions that result from that energy use. This is shown as a rating from A to G, where A has the lowest CO₂ emissions (best) and G the highest CO₂ emissions (worst).

The rating is also shown as a number. A typical building of its type would have a rating of 100. A building with twice the typical CO₂ emissions would have a rating of 200 (or G). A DEC must be accompanied by an advisory report containing recommendations for improvement of the energy performance of the building. The DEC must be renewed every year. The advisory report is valid for seven years.

DECs are produced using Operational Rating software. Buildings may also require an Energy Performance Certificate (EPC) if it is sold, built or let. The EPC rating shows the performance of the building’s fabric and fixed services. By contrast the DEC rating shows how well the occupier is using energy within a building and the trend over the last three years.