I need to make an easy ventilation article, but I will attempt to explain without pictures what I did (ok, husband's idea) to make draft free ventilation. Cut a long skinny rectangular hole in the roof. Mine is about 6 inches wide and runs the length of the roof. Line it with 2x4s on the two short sides and one long side. Put a piece of plywood (or similar) on top. Cover the other long side with hardware cloth (or similar). This can be anywhere on your roof and it will be higher than all your roosts. Even if the wind blows in it will not blow directly on your chickens and will be diffused as it need to turn a corner.