Yall should check out saskatchewan in summer. It's hot as fuck but humidity is low. Great place to vacationNone. However contrary to popular belief Canada can get very hot in the summer. Vancouver is much better but our house does often get intolerably hot some months. We face south and our attic doesn't cool well.
Nothing. No need. We have insulation, and that's it.
For upstairs, the insulation is for heat, since the roof cavity is like an oven. But for the ground floor it's for the cold, really.It certainly helps. My friend's shit house from the early 1970s has horrible insulation. It gets hooooot. He has 3 air conditioners and the damn thing is still unbearably hot. It just can't keep the heat out.
Open windows and window fans at night. Closed windows and shades during the day. Works just fine as long as it isn't in the 90's. Fortunately, I don't live where it's a near approximation to hell during July and August.
