Why would you do something like that? I don't see how idle curiosity could possibly warrant wasting energy like that...I was going away for a couple of days, so I decided to leaves the windows open in the flat to see how cold it was when I got back, it was 5degrees! (this is with sub zero temps outdoors).
That's extremely dangerous. If you get ice in your water piping you'll end up with some very expensive repair bills...Last year I often had temperatures of 0 degrees indoors, it usually was colder inside than outside
How could you even get indoors temps that low, don't you have any heating at all in your rooms? And how could you LIVE like that?
I myself had a somewhat uncomfortable winter this past season, the rooms below my apartement aren't heated so when there was a long cold-spell of sub-zero temps, sometimes down to more than -20C that lasted several months my floors crept down towards 16C, despite PCs roaring all day long crunching folding@home and radiators on full burn...