I'm new to this thread, but with the cold weather and obvious focus on energy use, have been trying to watch our indoor temperature.
The thermostat in previous years has generally been set at 21-22c (sometimes my missus - though she denies responsibility - has turned up up to 25c, then soon after compained it's too hot). This year it's at 20c (we tried 18c first, but that felt too chilly).
Heating traditionally in use October'ish to April'ish (weather-dependent) and set to be on a couple hours in the morning and, depending on time of year and weather, between 2 and 7 hours late afternoon/evening.
Was working from home yesterday and by lunchtime (heating had gone off around 7.30am), the temp where I work was down to 15c and I was cold. Had to put the heating back on.
I've read about the overnight temp in some people's houses falling to 11/12c so checked mine last night when I woke at just after 5am for a wee. Was 15.4c. So my insulation seems to be working alright.
I'm keeping the heating on today (again W'ingFH). i think keeping the heating on all day (periodically firing up for a brief time) won't be that much more expensive than having it off for 7/8 hours then having to work hard and for a prolonged time to heat the house from cooler. But I might turn the thermostat down to 18c.