Box fans are installed in the windows along the walkway and carry the cooled air into the barn down the center of each isle. The north side has misters about 8 feet away to avoid getting nests wet but still cooling the air. Sprinklers running parallel to or on top of outdoor hutches work as well although it tends to waste a lot of water and makes a mess in poorly drained areas. When leaving on vacation it is best to take the bunny to someone who will be able to tend to the cooling process. Don't leave the rabbit unattended for more than 12 hours without someone checking on it to be sure it has plenty of COOL water to drink and adequate cooling in the form of frozen bottles or misters etc.
Rabbits become overheated very easily and can die in a matter of hours.
As the earth rotates, the position of the sun changes as well. Pour the water over his ears. Rabbits cannot pant or sweat and exchange heat through their ears so cooling the ears is critical. When normal breathing resumes, remove him from the water and towel dry. Lay the rabbit in a shower stall or tub until normal activity resumes and fur is dry.