When the QuietCool salesman told me that I could save up to $1,800. per year on my electric bill if I would buy the QC-1500 whole house fans from him, I was very skeptical, but I wanted to cool my upstairs, regardless of the cost.
I have had them in my home now for ten months and it looks like the savings are true. I've already saved more on my electric bill than I paid for the fans, and the rebate from So. Cal. Edison Co. was like money from heaven (and my upstairs is now nice and cool in the evening).