"People who leave the windows open all day/night long - do you do this when it’s minus 2 degrees outside?"
Thick duvets, thick socks, hot water bottle. I cannot sleep without a window (preferably wide) open. I have central building heating (I'm in an apartment - I don't pay on usage but a flat fee for heating all winter) but often turn it down to minimum and open the windows as much as possible. I have a pile of fleeces in the sitting room and lots of hot water bottles. Last winter I shut the window one night because it was just too cold to have it wide open and I can't set my windows to "a little open" it's all or nothing, I think it was -6°c
If I have guests over and it's very cold I'll begrudgingly close the windows to be a good host, but once people have left - I open everything again, on both sides and block doors open so the breeze comes through. Very good friends know and get a hot water bottle and a fleece and clean fluffy socks! I cannot stand "shut in" or musty smells or even the smell of a bedroom after a night with the windows closed. I'm single know but it was one of the only issues I had with my ex who liked bedrooms sauna like hot.
I don't like artificial air freshener smells but have an essential oil spray in the loo and sometimes light candles ( but they have to be nice, either dyptique or rituals).
If I cook something smelly I'll clean up straight away and if thats not enough I'll put a big pan of water with some white vinegar, some cloves, some bay leaf, some citrus peel and a couple of drops of essential oil or vanilla in it and leave it on a rolling boil for a bit.