Yea I actually came up with the window reflector idea when I first started to put together the box. Then came on here and realized, I wasn't the only stoner with that idea lol.. I just didn't know if the Ir blocker under the reflector material would be necessary..
Oh and as for the passive intake, I can already tell you it works!! Its really wierd though, I was playing with the directon of my fan and it literally dropped 6 degrees with the door shut from just the direction of the fan, "mounted on the top of the cab blowing directly down at the plants/intake hole." Which is weird because I would figure this to be the least effective way.. I was getting up to 90+ aswell when the door was shut just from the fan being angled but now its holding strong at 84-85 if its 79-80degrees in the room. I'm gonna get my journal together and I'll be able to explain a little better but the point is, it worked! And I just realized this last night because I moved the fan and the temp skyrocketed then I was sitting there like wtf and realized what I did and sure enough, huge drop it temp! Hope this helps, I've been screwing with moving/changing lights for the last week. Kind of reminds me of when you started this grow lol.. Oh btw I'm only using 2 120mm 80cfm comp. fans for exhaust and one hole for the passive intake thats double the size of the exhaust hole and a 6" ocillating fan.