one of the tricks that I used to do was in this window I would build a box and inside the box there would be things like curtains if it was in a room and a home, or maybe paint cans if it was in a garage or basement. and the box with then be attached to the window and the window would be left open slightly and all the ducting would come into the box which would be pushed out the window. the decorations inside the box we're nothing but deception for people walking by or who may look at the window.