Section 420.150 - Natural LightingThe operator shall provide for each room used for human habitation
(A) transparent or translucent glass or other equivalent material which admits light from the outdoors and which is equal in area to no less than 8% of the floor area of that room, and(B) windows, doors, skylights, or transoms in the exterior walls or roofs that can be easily opened to a minimum of 4% of the floor area of that room; provided, that a skylight which, if open exposes the interior of the dwelling to direct rainfall shall not qualify.