well my closet is 5'x4'.......and the height of the ceiling is 12 feet(I hang the lights at 6'), huge closet! i cut it off to make it 5ft with wood board. well using your calculations i need a 240cfm. I will have a 170 on the lights exaust. and i have right now a 6'' 440cfm bringing cool 70 degree ac air into the closet, and plan to install ambient room individual exaust with a carbon sok. I mean i might be lagging on the cfm's for the reflectors, but i am gonna have a lot of cool air coming in for the room.