36. Ventilation.

(b) Unless the auditorium is air-conditioned the means of ventilation shall take the form of natural ventilation and power-driven exhaust fans suitably located and of adequate size for the purposes intended.
(c) Where natural ventilation is provided by windows or sky-lights which have to be darkened or obscured, free permanent top ventilation shall be arranged by means of ridge or ceiling ventilators. The clear opening of such ventilators shall not be less than one square foot for every 10 persons than can be accommodated.