Actually its more like this.
Room Air--->light--->fan--->filter--->outside
This way you pull the old, stale, STINKY air out of the room over the light and it cools the light, then it goes through the fan (duh
), then it goes through filter to get rid of smell, then it goes outside. This is how mine is set up, it works perfect. See the duct runs out of the room just makes a uturn and comes right back in. It is towards the top obviously. There is a 6in hole at the bottom of the room so it also pulls in cool, fresh air as it removes old air at the top. Then all this air goes through filter which is attached to the side of the shed. You could keep it inside or hide it somewhere else if you wanted to. There you have it. The air coming out is clean. The air inside is fresh. See in the top left of the first pic. The duct runs outside, makes a u and comes in right beside itself. The second one is just another view of that. The third pic shows the fan sucking all of this air across the light. The left side of the fan is the big hole, the right side is the small hole. It sucks from the right to left. Not sure of exact cfm, ill find out today. This is a active exhaust, passive intake. There is a 6in hole on the bottom right side. This is where it sucks in nice cool, fresh outside air. Covered with a filter
And the third pic is the filter on the outside of the building. Buy doing this not only am i clearing all the air every so often, the air in the rooms is changed constantly. This fan is sucking in fresh air non stop and pulling out the hot, stale, stinky air non stop. Works like a charm! What doyou guys think of this?