I installed a whole house fan in my previous place. Automatic louvers in the attic and a massive blower that I could open downstairs windows, turn the fan on and it would pull air in from the windows, push it into the attic, and out the louvers.

Not only did it quickly replace the indoor air with cooler outside air, it would also ventilate the attic, preventing it from quickly reheating the upstairs. I could run it for 5 minutes and get the desired effect, maybe 10 minutes in an unusually hot spell.

> With this technique you can quickly cool your house down and then close the windows again perhaps an hour later.

Not unless you wake at 3AM to implement it. In summer, by the time most people go to bed the temperature has not dropped significantly yet.

That depends on where you live. I used to live in a place where the lows are night were still very warm. Most of the night was too hot. Just before sunrise there was a moment when outside air was worth bringing in - but it was only long enough to cool the air in the house, not the mass of the house itself.

Now I live in a cooler climate. The highs can still get as high in the day, but it does cool of at night - nearly as soon as the sun goes down.