summer. it is no fans. i have a problem with fans because they could keep the birds to cool. what i mean is, fans work so well that when they are taken off, the birds get really hot and die. i have found other ways that in my opinion work better than fans. one is (and my favorite) water. you all know that chickens don't like water, but i found that if i put my hose on mist or sprinkle it cools them off quite a bit. i put it on a couple times a day, usually not at a specific time just when i feel they are really hot. 