6.3.1.1A.Natural Ventilation

(1) Except as permitted by Sentence (2), the ventilation required by Article 6.3.1.1. shall be provided by mechanical ventilation except that it can be provided by natural ventilation or a combination of natural and mechanical ventilation in (a) buildings of other than residential occupancy having an occupant load of not more than one person per 40 m² during normal use, (b) buildings of industrial occupancy where the nature of the process contained in them permits or requires the use of large openings in the building envelope even during the winter, or (c) seasonal buildings not intended to be occupied during the winter. (2) Where climatic conditions permit, buildings containing occupancies other than residential occupancies, may be ventilated by natural ventilation methods in lieu of mechanical ventilation where engineering data demonstrates that such a method will provide the required ventilation for the type of occupancy.