[wruza]

Curious if that saves any significant energy, if you visit home regularly. The same with summertime AC. I believe that allowing a properly insulated room to get hot/cold and then reheating/recooling it takes the same work, because half a day is barely enough for it to get equilibrium with the environment. For a week probably yes, but then again you don’t want your home to cross a freezing point too often. Am I right or naive here?

[jaclaz]

You are half-way right (or half-way naive, it depends on points of view).

Generally speaking (but it depends greatly on the specific home thermal properties and on the kind of heating or AC you have) it is usually less energy intensive to keep in winter your home at a certain temperature (lower than normal but not too lower) than to switch off completely heating and then when you get home boost to the wanted temperature.