i have found the key to temp control (in my case) i got a box fan as a trap door it fits perfect! then i got exhaust fans that are puashing air out an unused chimney. this creates a little low speed windtunnel across the grow area, and controls odor. the temp in the attic is always only slightly watmer/cooler than the inside temp (depends on outside) thus far i have had far more trouble with cold than heat. luckily i am situated at over 4,000 feet or so (in the east). we don't even need any A/c inside, but i think i'll have one in my attic.