We live in a medium-sized Victorian terrace house, which we share with (currently) four cats. Downstairs is knocked through from kitchen to dining room to living room. Upstairs has bathroom, bedroom, study.
Cats don’t like doors, so we took most of them off – there’s just a door on the bathroom, and one on our bedroom; we never close either of them fully. We have a thermal curtain across the living room/hall portal,which keeps in the heat from our woodburner (we try not to give our worldly goods to British Gas, and don’t use the heating unless we absolutely have to).
Our study is warmed by four monitors, a varying number of computers, and a load of other IT kit and, in theory, should be warm enough during the day. But the heat all leeched out into the landing, so before Christmas, Pete put up a curtain rail and we hung a curtain over the door gap.
What a difference! You can feel the difference as you battle past the curtain onto the landing. A good idea.