Heating when the power is off.

[Joe]

True BP but my suggestion is to use the existing heat already in the hot water storage tank. A lot of houses have this tank at the top of the stairs and if you open the door and remove the insulation jacket you have a fair amount of heat for a few hours. In fact we use the cupboard for storing laundry as it’s always warm.
I have other options but this might be a quick source of heat in a short duration power cut.