The trick is to run the whole-house fan all night, and shut it off when the temperature starts to rise in the morning (effectively "banking" the cold night air

The trick is to run the whole-house fan all night, and shut it off when the temperature starts to rise in the morning (effectively "banking" the cold night air by cooling the building mass). Turn the fan back on when it gets hotter inside than outside (usually 4-7 pm). Wireless indoor/outdoor thermometer are cheap nowadays! A "cheater" whole-house fan can be made by putting a box fan exhausting in a window (fill in the rest with cardboard etc), and opening windows on the opposite (ideally coolest, usually North/East) side of the structure. Remember: locate the wireless thermometer sensor outside the cool intake window[s], otherwise your temperature reading will be off. On sticky wet days, I find it helps to run the AC for a couple hours in the morning, after shutting off the fan. This dehumidifies the indoor air while it's still cool outdoors, so the AC runs more efficiently. Pro-tip: running an AC on LOW fan speed makes it dehumidify more effectively. Later in the day, I use AC set at 75-80 to "shave off" the worst of the heat in the afternoon/evening, prior to turning on the fan. Using only the fan without any AC, this results in a ~90% reduction in electricity used for cooling (at the cost of a few less-than-comfortable evening hours). Using the fan+AC technique, I yield about a 75% energy reduction (but with higher comfort).