All of the exterior doors in the main office/apartment building are actually not exterior if that can possibly make any sense. They all lead to the outside, but are in fact hollow core uninsulated interior doors. We replaced the first of the doors that leads to the heated living quarters with a new insulated metal door yesterday. The weatherstripping on the old door was in poor condition with small cracks of light from the outside visible when the door was closed. The top half of the new door is double pane glass that lets in light to a poorly lit staircase. Having the staircase lit with natural light will allow the stair lights left off during the day, while having significantly more light. The glass should also allow a modest amount of solar heat gain during the afternoon.