You don't if you have floor to ceiling double ended ventilation. Ie a door on one side and a door on the other....
I have my miners in my garage and this will be the first hot weekend of the summer. I'm hoping that by opening my garage door a few times a day I can recycle the air. Its north facing and thats where the cool wind comes from. If that doesnt work I have a 12000 BTC portable AC unit ready to go. Would rather not use it though.
Exactly! For the vast majority of the year I cool my miners passively, with 0W. In the summer I simply add a 60W fan to help aid the ventilation to ambient. Its 40x more efficient than using AC.