Nice build with water cooler jug. The only issue I see if finding a fan (if you are building something like this from scrape) that puts out a decent breeze at 5 volts. Most of the fans I have are 12 volt based from PC scraps. Oh and interesting to see you can get cheap pumps that are USB powered.
http://www.instructables.com/id/Personal-Solar-Powered-Air-Conditioner/