Dartington, Droridge, Brook House
- Cavity wall insulation using mineral wool fill
- 95% UPVC double glazed windows
- Ground source heat pump from a 40 metre bore hole
- 250mm loft insulation added
- All appliances A-rated
- 95% low energy lighting
- 2.8 kWp Solar PV system on east facing roof. 4kwp PV on west facing roof (total 6.8kwp PV)
- Solar thermal – 4 sq m evacuated tubes
- Double usage of water: through the heat pump to heat the house in the winter, then through a second tank and via a UV filter for all domestic purposes
We are both Drama Teachers and I run a private practice training adults in Presentation Skills. We have two boys aged 8 and 11, one of whom is at the new eco school in Dartington, the other has just started at KEVIC. We had some money left over from the sale of our previous house in Sussex when we moved down here which is where the initial investment came from.Motivations:
In the beginning our main motivation was a green agenda one – to see what energy savings could be made in a small detached house. Could they be done in a way that was economically viable? We were not so motivated by financial benefits initially because the payback times we were looking at when we first started were pretty long (although they have now dropped).
It’s a 1960s small detached, 4 bedroom house on an estate. It was built with cavity walls and large windows, other than that there’s nothing particularly special about it. We moved in 8 years ago and started the retrofit over 6 years ago.
Our brief was to see what was possible in a little house – an ordinary house like this. We started with the idea of solar because we didn’t think anything else was possible. I think it was the solar chap that told us about heat pumps – which sold us down that route. So we started by fitting 2.8kw of solar power. Then we decided to take the plunge and we drilled a bore hole and installed a ground source heat pump that uses the temperature of underground water to heat our house and domestic water. The heat pump itself runs on electricity. The input output ratio is one kw electricity used produces 4 kw equivalent. The bore hole also supplies all our domestic water usage. Then we fitted a solar hot water panel as well. We have put another 4kw PV array on the west facing roof so we’ve now got 6.8kw of PV.
There were many pitfalls that in retrospect could have been avoided or at least mitigated. Once it was finally all up and running, only then did we became aware of the huge benefits. This is one of the reasons we are prepared to share our experience with anyone else contemplating a similar project.Benefits:
From a practical point of view there isn’t much difference in living in our house prior to and following the retrofit, it’s basically the same, and that’s the point. It’s not a question of feeling benefits, other than that we would rather our energy was coming, as much as possible, from alternative sources rather than from conventional ones. The alternative energy is doing the same job as the fossil fuels were doing before.
One of the advantages of the ground source heat pump is that it just fits in with a conventional radiator system. So it heats the house in exactly the same way as our gas central heating system did.
We were quite pleasantly surprised with the financial benefits. We are a family of 4 with 2 young children so our energy usage was quite high before we fitted anything. So the combined saving of electricity bills and £800 on water, is between £3000 – £4000 pounds a year. We now have no energy or water bill and in fact make a small income from the solar PV. Therefore we are completely insulated form the increasing energy prices, so even though there has just been another 10% hike in prices across the board it makes no difference to us.
The other interesting thing on the financial front is that when we first did this you were lucky to get 5 pence a unit for exporting PV electricity. Even the tariff on the old PV array has gone from 5p to 14p. So as energy prices have gone up that has meant what we get for the electricity has gone up – now we get 43p a unit for the 4KW array via the initial feed in tariff that was offered. So in one sense, an increase in energy prices has resulted in quicker pay back time for us, which is something that we could not have predicted.Favourite Feature:
I suppose the favourite feature is that we are saving money. The major dividend it’s been for us is it’s around £4000 a year that we don’t have to find in cash. The 4kw array generates about £1300per year and the other one which is paid at a lower rate probably generates another couple of hundred. So you’re talking about £1400 – £1500 coming in with an energy bill of between £1000 and £1100, so as I say it comfortably takes care of both the energy and what little there is left of a water bill. Our water bill 6 years ago was £8 – £900.00 per annum and it is now about £130.00.