We have a guest quarters located above our garage (roughly 230 sq. feet w/ bathroom). We'd like to install an air conditioner, but the windows won't accommodate one -- the ones in the front open like doors while the one in the rear, which is probably 70 years old, has hinges in the middle so that the middle panes can open out. So, a standard window model is not an option. If we get a portable unit, how can we connect the exhaust tube to the outside? So far, our brainstorms include: 1) knocking out a single pane of glass, 2) having a glass-cutter knock out a circle in a pane of glass, 3) replacing one of the front window doors with plexiglass and using the "spacer" provided by portable units. Are 1 and 2 too destructive to the house? Replacing a pane of glass in the event we sell the house down the line is pretty easy, no?