In New York right now, it’s insanely hot, so I’ve been out shopping for air conditioners. I was thus tickled to read about the ultimate low-tech cooling unit, created by a Canadian engineering student who was too broke to pay for an A/C. For $30, he wrapped a regular fan with copper tubing, then filled a garbage can with water and ice. He pumped the water through the tubing, using gravity as a free source of energy. Presto — it cooled the room for up to three hours per filling, as he describes on his site:

If you look closely, you can see the condensation from the incoming icewater, but no condensation on the tubing leading out. This is perfect, as it means that heat is being transferred from the room to the water.

I love low-fi hacks like this.!

(Thanks to Boing Boing for this one!)