The 10,000-Btu GE Profile Clearview PHNT10CC is an Energy Star-certified inverter air conditioner that can fill a room up to 450 square feet while taking up only about 4 inches of window space. Instead of balancing precariously on top of the sill, this N-shaped model hangs down over the wall, freeing up the window above it. The AC does stick out into the room (about 9 inches), and you may need assistance lifting it over the windowsill.