My spouse and I have a disagreement about how to most efficiently use the air conditioning in our home. During the summer when the air condidtioning is running, he insists on putting a fan in the 2nd floor window pulling out what he says is hot air. I agree with this philosophy initially when you turn on the air in the house until it comes down to temperature, however he leaves it on 24 x 7even when it's 100 degrees outside. Heat pours into the house requiring the air conditioner to run non-stop.

I feel he is wasting money with this philosophy and insists it has to do with thermodynamics and heat rises and cool falls. Although this is an accurate statement, I feel that the hot air pours into the house though the fan in the window even though the fan is blowing out.

Who is right?

If you have vents that carry the cool air upstairs, he is pulling that cool air out with the hot air.

If you have no vents upstairs, I say his idea may be worth while, especially if you have a way to limit the amount of open space around the sides of the fan.

Sounds like my husband and we don't have AC, so... years ago when he set up fans he would do exactly your husband is doing. But, I liked the fan on me so I can feel the cooling effect. And by the way, his theory is all shot to pieces if he has AC and he ls leaving a window open to pull hot air out. Too much energy being wasted.