I'm not sure buster, maybe i'm a bit too paranoid but i'd insulate. However good your fan is for good growing conditions you'll want your temps around 75-80F and thats gonna be hotter than most lofts. I'd also think about cooling your exhaust before it goes outside i've heard on infra red it shows up like a waterfall. But i don't know if all police copters have infra red, or maybe you dont get copters where you are?