Tuesday, November 15, 2011

EPC for Peveril Solar House

15th Nov 2011: Ive had an Energy Performance Certificate (EPC) for the house. We had a visit from Steve and Ed of http://www.energy-assessors-nottingham.co.uk/ last Friday. They said it was a very high assessment, but it still comes out at 91 which is a high B+ rating. It is a bit disappointing but I know why.
    I know that we start out with a disadvantage, being Brick/block with double glazing, and being detached. The existence of a Gas fire (that we have only for the pilot light and for emergencies) knocks 5 points off the rating straight away. I didn't expect the software to understand the process of storing heat throughout the summer in an earth store. The guys are very sympathetic, but this is the way the EPC software rolls it out.

The actual metered performance of the house does not get included by the software, there is a box ticking exercise that then assumes the contribution that each component makes.
     So, having a GSHP is a credit, but quite how efficiently it performs is not included. Having the PV on a 40deg pitch, not a 30deg pitch is a negative. Not having a Wind Turbine is a negative, as is not having a conventionally installed solar thermal panel and tank. We couldn't have either of these. Rushcliffe BC don't give planning permission for WTs unless they are below the roof-line, and a solar thermal tank would be a major legionella risk for my dear wife - and thermally it would be redundant as we are sending enough heat already into the main thermal store.
    As a result the software assumes that we use 45 kWh/sqm/yr for heating and hot water, whereas the real figure as metered is 26.6 kWh/sqm/yr, and the heating alone takes less than 20 of those.
    I'll have to accept this philosophically - his mention of 'Time and Zone control', refers to systems in which programmers can manage each room separately - for which there seems to be no need in a very small box-like house with good insulation values, and no swimming pools, libraries or granny flats.

Ed writes: "The specifics of the property do fair much better than what is assumed in an Energy Performance Certificate.  However, I am still impressed that without the use of the gas fire, the house manages a score of 96 which is absolutely superb!
     "I’ll just provide you with a few scenarios with the current setup and the impact they would have on the EPC.  The practical impact would be different however…  This is based from a starting point of 91 points.
  • Add wind turbine – 94
  • Time and temperature zone control – 92
  • Without gas fire – 96
  • With conventional solar water heating – 93"

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