Unfortunately while I purchased this unit last fall/winter I have yet to have it installed. I have a contractor coming the first weerk of May to do install. He ha measurements and is cutting a clear piece of plex-glass to allow light into window. I will speak to him about specifics but I can tell you my window is also short- no more than 15" wide and he says it will fit no problem. Sorry I cant be more specific -I will post something when installed. Thank you.