I live in a climate which is very dry.It can get pretty hot in the summer and many people have expensive air conditioning. I had an evaporative cooler or swamp cooler installed on my roof and it's wonderful.
You don't have to shut all the windows and doors, it cools quickly and it costs pennies to run. It can be installed in a window, a wall or the roof. I recommend it.
Gary's note: I see a lot of these in homes say 20 years old...not much to look at but they do the trick...thanks Patricia