Instead of having a heat pump an alternative option is a wood burning stove. The concern about the heat pump is the running costs. Even though the efficiency is 1 to 4 (1kWh in gives 4kWh out), the economics & CO2 savings are somewhat different.

Now if I burn wood, then apparently, this is carbon neutral (providing the wood is coming from sustainable forests). If I maximise the efficiency of the house insulation then I will need even less energy to keep warm.

A Clearview stove can have its own air intake, so even if the house is sealed (i.e. no drafts like a passive house) air can be supplied to the stove box. They claim to be 88% efficient and some heat could be recovered from the pipe. If I can find a way of prewarming the incoming air from this pipe for a heat recovery system, I might be able to get some of the 12% back.

Having a back boiler reduces the efficiency of the stove, and it has to run on a “fast burn”. Obviously more wood is required. Not having a back boiler means I have to look at an alternative solution for heating my hot water tank for winter.