Section 121(2) in Kolkata Municipal Corporation Building Rules, 2009
(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 on Building Services of the latest edition of the National Building Code of India.Provided that in no case, the minimum aggregate area of the openings of habitable rooms and kitchen, excluding doors, shall not be less than one-tenth of the floor area.
