I know IABU but in my defense MIL is two weeks into a stay (length of which still unconfirmed)
We live overseas and it is very very hot at the moment.
My house is not a traditional UK layout, three floors (entry via the middle floor, which has living room and two bedrooms, down to "basement" where we have the kitchen, dining room and a big patio onto the garden and two more bedrooms on the top floor.
Even if we are in the living room in the evening, we leave the patio door open downstairs because it cools the house down, and less need for aircon (and horrific electric bills) It is perfectly safe to do so.
MIL doesn't want the patio door left open.
(this is the woman who locks all her doors and windows and draws the curtains by 4.30pm winter and summer) - I remember we stayed with her for two nights last year (in UK) and sweltered in her living room with the curtains closed on two of the most glorious summer's evenings of the year.
She keeps coming up and downstairs from the living room to the basement and back again, asking if she should close the door, dh says no mum, leave it. OK, she says, sits down for 5 minutes, lather, wash repeat.
There is loads of other stuff going on, but the doors thing is making me very stabby.