October marked the end of the first year with the heat pump and the other energy saving measures we have put in place. The results are very interesting and to some extent surprising. We can look at them in a number of different ways.
Our baseline was 2004 when our heating oil cost £2,431 and our electricity £2,292, giving a total energy cost for the house of £4,732. Incidentally, this corrects the figure for electricity use we were using back in August
Now in 2006 (Oct 2005-Oct 2006) we have only electricity to consider. This breaks down as non-heat pump £1,481 and heat pump £1,663, giving a total energy cost of £3,144.
So we may conclude that we have a crude saving of £1,579 on the year, about half from using less general electricity and half from using the heat pump instead of oil.
Perhaps more interestingly, the cost of oil in 2006 would have been £3,403, which would have made us another £1,000 worse off.
So we could say that the heat pump (cost £13,000) will pay for itself in seven years at 2006 oil prices.
However, before generalising these findings, we must recognise that the initial energy requirements of the house are so high that other people find them implausible. In particular the typical UK house is reckoned to use 3,300 kWhs a year, whereas we are using 14,700 kWhs without the heat pump and even after the savings we have made. So there is plenty of scope for reducing this total. We should probably start with more efficient fridge, freezer and washing machine. And more care in turning off gadgets on standby.
As to the heat pump itself, it has clearly been an excellent move in terms of both carbon and cost savings. However, there is also considerable scope to reduce further the annual cost of £1,663 in the electricity it uses. We are planning further insulation, as well as more fine tuning of the pump itself. For the full year it ran for 4,755 hours, or 54% of the time, using 3.2 kW when it was on. That is a percentage we must reduce.