Three things: an emergency escape opening, ceiling height, and alarms. The window needs at least 5.7 square feet of net clear opening, at least 24 inches of clear height and 20 inches of clear width, with the sill no more than 44 inches above the finished floor, and the well outside needs at least 9 square feet of area, a 36 inch minimum projection, and a permanent ladder if it is deeper than 44 inches. The room also needs 7 feet of clear ceiling height, hardwired interconnected smoke alarms, and a carbon monoxide alarm outside the sleeping area. A room without egress can be an office, a gym or a den, but it cannot be inspected or listed as a bedroom.