Exhaust/Ventilation Question

I'm in the process of planning out a stealthy-ish grow cabinet. Right now I see the dimensions as being 32" X 14" x 20" with a 4" pc fan below plant level for a fresh air draw, possibly on a timer and a small battery operated fan at plant level just to keep the breeze across the leaves. Haven't quite decided on my order control but once I have that set do you think I need another fan for exhaust or will there be enough air flow for passive ventilation? If I do need another fan do I need to run it non-stop? Once I actually get everything sorted out I plan on starting a journal from build to bud. Any ideas or criticisms are more than welcome. I am using CFL's for light so....

Anyone? Before I go crazy on the fans some input would be nice.

20" height? ouch.. Better do a sideways grow.

And with just 1 PC fan.. as intake? No exhaust? It could work with LED, but CFLs get hot in numbers, and they're only effective in numbers, so..

I would at least double your ventilation, one on the exhaust (high aligned to one side), one on the intake intake (low, opposite side)

No 36" height 14" x 20" depth and width. Have to work with the space available. I kind of thought I need at least one more. I'm guessing they will have to run almost non stop to keep the heat down. Thanks for the heads up.

I would run an intake and exhaust. IMO the exhaust is more important than intake because heat needs to come out of the area. I always run both.

Do run them both non-stop or would something like I a working on only have to be ran for a few minutes every so often.