My closet is 4' wide, about 2' deep, and about 9' tall and just happens to have a pop out in the ceiling for access to the "attic", which is really just a crawl space between the ceiling and the roof. The opening is just the right size to mount a box fan to for exhaust. When and if smell becomes an issue, I'm gonna try charcoal filters attached to the fan and see if that works. For light I got 4 twin tube 48" fluorescent fixtures from Home Depot for like $8.00 each and $3.50 a set for the tubes. I used cool white tubes 'cause they have the most lumens (3200) and the temp is 4300k. I was looking for 5000k but the daylight tubes are 6500k and I didn't know if that was too much past 5000 or if it even mattered. They are also about twice the price but not quite as bright. I thought I'd use plant and aquarium tubes for flowering but they're dark. Only about 1700 lumens but they're supposed to be the right color. I don't know