@Janet_52square @IcooIey @sinituulia not heating the bedrooms was a thing also here in the north of Italy: you would have a cast metal stove like the one above in the kitchen (with an oven and range) with a fire constantly going (and a kettle of water and possibly some soup cooking on the range), maybe a fireplace if there was a separate living room, and nothing in the bedrooms.
And you only went to the bedrooms to sleep, and use extra warm blankets (and a night hat). And possibly put a perfectly safe metal container full of embers from the fire in the bed a short time before you went to sleep to warm it up. Or later on a slightly less unsafe electric blanket.
Temperatures here are a bit warmer than in Finland, but winter nights are often just below freezing even today, and of course used to be colder.