Ventilation of Rooms and Spaces,

(1)  Except as permitted in Sentence (2), rooms or spaces in a residential occupancy shall be ventilated by natural means in accordance with Subsection 9.32.2.

(2)  The natural ventilation of rooms or spaces required in Sentence (1) may be provided by mechanical means.

(3)  Where a room or space is not provided with natural ventilation as described in Sentence (1), mechanical ventilation shall be provided to exhaust inside air from or to introduce outside air to that room or space at the rate of one-half air change per hour if the room or space is mechanically cooled in summer, and one air change per hour if it is not.

Article 9.32.1.3 Ontario Regulation 332/12 Building Code,   Information published by oncodes.ca for educational purposes only.