Electricity is 24.847p per kWh

Depending on the pattern of heating demand, it might be possible to get a better price than that. I know the old E7/E10 tariffs aren't often offered to new customers these days, but several suppliers are now offering "heat pump tariffs" with usually significantly lower unit prices for a fair chunk of the of the day (deals vary but something in the region of 10-11p/kWh for a total of 7 - 8 hrs/day usually in two or three slots, early morning, early afternoon and late evening). That's not to say you can only run the HP during those hours, but it can bring the average unit cost down quite a bit, especially when it's not quite so cold you can  weight the running times to the cheaper periods. Also if there's no other gas appliances, discontinuing the gas supply should save you the standing charge - which probably isn't huge, but adds up.

I agree 100kW sounds huge - you could probably heat 10-30 houses with that.

   - Andy.

AJJewsbury said:

I agree 100kW sounds huge - you could probably heat 10-30 houses with that.

Modest well-insulated ones!

If you heat the house in the morning until shortly before the household departs for work or school; and again from home time until bed time, you need enough to heat up the environment. That does not mean an average output of 100 kW, which is why I asked about the use of the building.

AJJewsbury said:

I agree 100kW sounds huge - you could probably heat 10-30 houses with that.

Modest well-insulated ones!

If you heat the house in the morning until shortly before the household departs for work or school; and again from home time until bed time, you need enough to heat up the environment. That does not mean an average output of 100 kW, which is why I asked about the use of the building.