I used one of those in college. I lived in an un-air-conditioned apartment in Denver, and during the summer it could easily get over 90 degrees inside. The swamp cooler would bring the temperature down to about 75 (so long as I closed the blinds). Also, one of my friends had a whole-house swamp cooler, mounted like an air-conditioner on the roof of his home. They work beautifully in dry climates.