i feel like a creep... im dooing the same thing with a closet that looks just like yours and my parents agree with me aswell ..... they want some of the dope though... lol
keep your door open... bye a sheet of thick plastic or some sort of tarp material.... stick some foil or mylar to it.... then replace where your door was.... cut the tarp like material in half use some strips of mesh that sticks to its oopposite side... place where you cut it in half to seal...