Section 74(2) in West Bengal Municipal (Building) Rules, 2007
(2)In any case where light and ventilation requirements are not met through day lighting and natural ventilation, the same shall be ensured through, artificial lighting and mechanical ventilation as per the latest provisions of section 1 of Lighting and Ventilation of Part VIII on Building Services of the latest edition of the National Building Code of India :Provided that the minimum aggregate area of the openings of habitable rooms and kitchens, excluding doors, shall in no case be less than one-tenth of the floor area.
