And this shows how internationally building codes can be very different. In Italy a room, any room for residential use, not only needs a window, but the window

And this shows how internationally building codes can be very different. In Italy a room, any room for residential use, not only needs a window, but the window(s) surface must be at least 1/8 or in some cases 1/12 of the floor surface of that room, a windowless room can only be a bathroom (with a compulsory exhaust fan) or a closet/corridor/storage/utility room. But this comes not from fire related laws, but rather from minimal health requirements (natural light, ventilation).