Since I started brewing my own beer, one thing that has cast a shadow over all my brews is fermentation temperature. I live in Hawaii and the weather here is usually on the warm side. On top of that, I live on the second floor of the house which must get up to 85-90?. We have no air-conditioning and only a few fans.
To tackle this problem, I placed my fermenter in a small enclosed space and used ice packs to try to cool the small space. I was replacing the ice packs twice a day. This was only to get my beer to a steady 75?. Not quite optimal. I made two batches like this and both showed signs of high temperature fermentation.
My next plan, also a low budget plan, was to use evaporation to keep my beer cool. I found that in general, it was cooler outside than it was in my house, so why not set up a space outside to put the fermenter? That is what I did. I set up a corner of my porch to accommodate my needs.
First, I made a small tub and filled it with about 6 inches of water to place the fermenter in. After placing the fermenter in the tub of water, I took an old towel and cut a hole in the center of it. I then wet the towel and draped it over the fermenter with the airlock fitting through the hole in the towel so that the ends of the towel were lying in the water. To finish it up, I put up cardboard walls to keep it out of the light.
With any luck the cooler outside temperature along with the towel evaporation will lower the temperature of the beer enough to acquire fermentation at the proper temperature.