Pets? One of my cats found a nice solution for that: recruit some dumb human as her heating pillow. (The “dumb human” is me, by the way.) And when I’m not on the bed she sleeps inside a blanket folded in the shape of a pocket.

…although winter here rarely goes below 0°C, subtropical region and all that shit. If I was a bit souther I’d probably have some heaters in the bedrooms, and that’s it - there’s no reason to heat the whole house.