Depending on the kind of heating system you have and the temperature differences you talk about it can be cheaper to heat the house to a constant temperature (because your heating can run more efficiently under lower load).
Depending on the kind of heating system you have and the temperature differences you talk about it can be cheaper to heat the house to a constant temperature (because your heating can run more efficiently under lower load).
Correct, or the people doing this for environmental reasons... it's probably not better to do this. It would be better spending money on better insulation (assuming it isn't up to date).