I'm currently finishing an attic that's about 450 square feet. It's rectangular shaped with 4 foot knee walls. There will be a bathroom on the north end of the attic complete with shower, sink and toilet. My contractor is recommending baseboard heat and a window air conditioner on the southside of the house. The north window will be enclosed by the bathroom. My concern is that the window air conditioner on the south side of the attic will merely spill cold air down the steps and not adequately cool the north end of the attic space. Someone suggested a PTAC unit for both heating and cooling but my concern with that is a PTAC unit might lead to frozen pipes in the bathroom in the winter. Any ideas? Thanks