Tuesday, 12 October 2010

Energy Performance Certificates

My letting agent has just sent through the Energy Performance Certificate I had to have done in order to let my house in Exeter. The consultant was very nice and let me tag along while she measured and made notes, and explained what she was doing.

The building's performance is "rated in terms of the energy use per square metre of floor area, energy efficiency based on fuel costs and environmental impact based on carbon dioxide (CO2) emissions". Here are the headline figures for my house. I suspect Broad Marston Manor would come out as H, but Mucknell should be very good.

The Certificate also lists recommendations to improve the house's energy performance to the "potential" ratings given in the right-hand columns. In my case, this was just to replace the boiler with a condensing boiler. It then suggests "further measures to achieve even higher standards" - solar water heating and photovoltaics, which would improve both the energy efficiency and CO2 ratings to B86 and B82. It gives more information about all of these measures, and a list of simple actions that can be taken today to "save money and reduce the impact of your home on the environment".

The problem with the recommended measures is the old landlord-tenant conundrum: if the landlord makes the investment, the tenants benefit from the savings on bills; and if the tenants make the investment, they might not stay in the property long enough to realise the benefits, and the landlord benefits from the property's increased value. So unless the Certificate gives suggestions for how to get round this problem (e.g. where the landlord could get grants or about the companies that are fitting PVs for free and taking the Feed-in Tariffs) it's a bit of an academic exercise. I do hope, though, that my tenants at least follow the simple actions.


  1. This energy efficiency data is useful, but as with all over-simplifications is somewhat flawed. The problem is that it does not take into account the number of occupants. I am not a physicist but I imagine the correct units should be something like Joules per hour per metre squared per number of occupants to get a truer idea of the energy efficiency of the impact of families, individuals, or groups of individuals occupying a house or flat. Larger buildings are clearly going to be less energy efficient, unless they are occupied by more individuals. I will now rapidly re-confirm that the radiators are off in our various unoccupied rooms.

    Stephen T.

  2. The software assumes number of occupants depending on the size of house. The other numbers given for typical usage and bills are probably therefore for a 3-person household. Mine were much much lower. But this also means that the suggested savings on bills of the recommended measures are very misleading.

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