Thursday, September 3, 2009

Carbon Zero houses

The government declares that all new houses can be Carbon-Zero by 2016. I dont believe such as thing as Carbon Zero house can exist unless you go to the extremes of a scheme like Hockerton housing, in North Nottinghamshire - who provide excellent courses on carbon zero design but who use tricks in their book that normal house builders cannot use.

Our house has been Carbon-Zero since it was built solely by 'sleight of hand' because we buy our electricity from Good Energy - who only procure Wind Power and other renewable sources. But Offsetting is a trick like Carbon Trading, and as an architect seeking truth, I don't 'buy' it as an answer for all new houses, unless the whole country is able to switch to wind power.

Can we do it? If we upgrade our roof to the maximum with PV (which is 4kW), and even if we had a south roof, this would improve performance by 1500 kWhr/yr (half of its annual production). We hope to reduce our electric consumption 10% by using Solar Earth Charging, but what more can we do? We already have the best insulated house in West Bridgford, we have an efficient modern heat-pump that draws heat from the soil with a CoP of 3-4. The only thing we did not fit was a Heat Recovery system, which is one of several technologies we can use. MVHR will save a small amount of heat, but will burn yet more electricity and makes the house stuffy. We tried a full size Rainwater collection tank; this is good but doesn't save energy quantifiably. We had a planning application turned down for a Wind turbine, but this would have been able only perhaps to make 500 kWhr/yr. One fixed to the house would produce negligible amounts and shake the brickwork, and a more powerful one on a mast in our tiny garden would overpower the neighbours. We already grow vegetables. We cant keep a pig in the back as it would turn the garden into a mud yard, and what would we do with an entire pig when it has to be turned into meat? We have no pond to grow our own fish in, like Hockerton.
It seems that we shall be 'carbon zero' only thanks to the favourable Feed in Tariff on our PV roof. If anybody has further ideas on what one can do with a house in West Bridgford, please advise!

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