(1) In a room having required daylight openings, the sum of the floor areas of alcoves and the like, which are not directly visible from at least one required daylight opening, shall not exceed 10 per centum of the total floor area of the room.

(2) Portions of screens and partitions which are glazed with clear white glass from a height of 1 metre above the floor-level to the top of the screen or partition shall not be regarded as restricting visibility.