A: The less the window area the better the thermal envelope will be. Often houses have about 15-20% window area compared to wall area (without the windows) but our house has 42% and we still have a zero carbon footprint. This is one of the main reasons we need so many solar panels to get to a zero-carbon footprint. Overhangs are great for allowing the sun in in winter and keeping it out in summer. The optimal width of the overhand is about 3’ at 9’ height and 6’ at 18’ height.