The Sketch I did... Well as I recall in the first room the air intake was at the bottom. Just filtered. It had a big exhaust outlet at the top of the room the went outside then when you cross into the flowering section, he ported in cool air from the low air intake, ran it through a fan, through his HPS and then up and outside. Another air vent downlow is the fresh air for the plants. So three seperate air intakes down low and three exhaust ports above. I am pretty sure that is the way he had it.