Our Barn was built in 1667 and we are the first humans to live in it 4 years back. 2ft stone walls and then water/vapor barrier and then 18" of herdwick wool insulation betwen the interior metal skeleton which has all the interior floors and walls fitted to it. So inside it is square and outside is just a facade.
The only room that ever gets cool is the main bedroom as one side is made of glass, so that and the dining room (lowest floor) are the only ones that ever have the underfloor heating used, and that's turned off now it's above zero.
Wood burner is all we need to keep the whole house hot... but 19° is the max I will ever set it to... any more than that and the Golden Retriever passes out!
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