I would just fill a tub or kiddy pool with cold water and plop into it (or swab myself with a cold water washcloth) every time I felt warm. In fact, that's what I've been doing this week, 'cause it's stinkin' hot here. It works best if you can hit the yard or balcony afterward to catch a slight breeze, and the closer to naked you are, the more efficient this becomes.
Plus, I guess the tub of cold water would slightly cool your house because heat energy from the air/house would go into the water until it reaches equilibrium.
But I don't think any of this will make a huge difference.