I know that question is too open ended to really answer. Each house will behave different. Each room will behave different depending on windows, exterior walls, etc. But I'm just looking for some sort of estimate.
Say it's -15C outside and +20C inside at midnight. If i left the furnace off (gas forced air) all night, what kind of temperature could be expected at 8am? I guess a "If it drops lower than X then you may have issues" is the kind of answer i'm looking for.
The reason i ask is because i'm an insanely over-critical person who wants to squeeze every bit of efficiency out of this house until the next one which i will have built properly. :-)
I'm in the middle unit of a 3 unit townhouse. So i share a wall with each nieghbour on the sides and only my front/back walls are exposed to the elements. However I have a 2nd story which neither of my neighbours do, so upstairs is exposed on all four sides. Because the vast majority of my main floor walls are shared with neighbours i figured that my heat loss should be significantly better than any detached house. But i have nothing to compare against. Buit new in
2001 according to ontario building code. I think that's r-34 in the attic and only r18 in the walls. All the windows are double paned. I can't feel any air leakage and no condensation or ice ever forms between panes but the bedroom windows ice up like hell every night along the bottom edge. (35% humidity inside at 19C with -15C outside).I haven't done any tests to see how quickly the temperature drops but i was just looking for some sort of general numbers to compare against once i do.
any thoughts appreciated.