I say, I say, I say, what is the difference between an EPC and a DEC?

Unfortunately there is no punch line, the rather tedious and simplistic answer to this question is:

An EPC (Energy Performance Certificate) is required for a commercial property over 50 square metres at the point that it is marketed for sale or let. It shows an asset rating for the building which conveys its potential to be operated efficiently and is updated every ten years.

A DEC (Display Energy Certificate) needs to be displayed by public buildings with a floor area greater than 1,000 square metres. It shows an operational rating which conveys how efficiently the building is actually being run and is updated on an annual basis.

This however begs the question; why distinguish between the certificates that are produced for public buildings and those that are produced for commercial properties? What is an even greater puzzle is why public building certificates should focus on operational efficiency whilst commercial buildings are only concerned with the asset rating and not the actual energy use.

After all when the Carbon Reduction Commitment comes in to force in April next year both public and private sectors will sit on the same league table, and their position on it will be determined by their ability to reduce carbon emissions, which will involve improving both the asset and operational ratings of their building stock.

In reality the answer to the original question is that DECs and EPCs are two halves of a larger picture and without both halves it is difficult to make any meaningful evaluation. For example, by way of an analogy, if Bill gets 40 miles to the gallon from his car and Ben gets only 30 it would be tempting to suggest that Bill is the more efficient, until that is you learn that Bill is driving a Ferrari and Ben a Honda Civic.

So if we are going to have any kind of certificate (and as an accredited energy assessor I am not suggesting that we shouldn’t) lets have one that is the same for all buildings and provides a rating based on both the asset and operational efficiency of the building.

One puzzle however remains. Both DECs and EPCs are born out of the European Performance of Buildings Directive (EPBD) the redrafting of which is currently the subject of a piece of government consultation. As part of this consultation answers and opinions are sort on a whole range of issues including whether or not DECs should be extended to all public buildings over 250 square metres, and whether EPCs should be included as part of advertisements for properties. None of the questions however are concerned with whether or not the existing system of producing DECs and EPCs provides any useful or meaningful information. It is rather like asking if jelly should be fixed to the ceiling using nails or screws.

Next week…..Why it doesn’t matter what the difference is between an EPC and a DEC.