Ideally our house would have separate heating circuits for each floor as the bedrooms do not need warming during the day. I could fit valves with timers to optimise this. The house is pretty well insulated, so the savings may not be huge.
A lot of old houses just leak heat, so it gets expensive. I know some people use heated jackets so they can turn the heating down.
Yep, this old house has a sun room with single pane windows. I put up thick curtains between the two access points between the sun room and the main part of the house to close them in times of extreme heat and extreme cold. It works well enough for now.
It's below freezing here tonight, so I'll be sure to close all the curtains as it helps. My sister lives in an old house in Scotland. I think they are limited on what alterations they can make to 'preserve the character', but homes have to be liveable.