dude just cause its a closet doesnt mean you can let the air stand still. even with cfls that need to venting(for heat) your plants still need fresh air. heres what i did years ago. hang 2 pieces of black and white poly over the door frame with the door open. cut fan holes, one in the top, one in the bottom(exhaust and intake). that way you cont have to cut holes in your door. when the lights on, open the door, turn the exhaust and intake fans on(could be house fans whatever u find), and then when your lights turn off, turn the fans off and close the door. be creative, these people here were just giving you examples so YOU could work with them.