In talking with neighbors with neighbors that bought a home with no A/C, I asked if they had a whole house fan. In the Denver area, Zone 1 on the map, I can pre-chill my home by opening the windows in the morning hours and dropping the temperature by 7-10 degrees. This allows me to get to evening hours with a house temp of 77F. I can then open windows in the evening hours to vent heat out again.
Now, I do this sometimes. But if I had a whole house attic fan, I would make it more routine. The nice thing about this system is getting the hot air out of your attic and replacing with cooler air. Otherwise that hot air keeps hot air in the house and causes your A/C to run longer.
For more info, check out this website: http://www.wholehousefan.com/