Ottawa By-law 2013-416, s. 66 — Property Standards By-law

1) Every room where people work in a non-residential property shall be provided with natural ventilation which shall,

• a) consist of an opening or openings with a minimum aggregate unobstructed free flow area of 0.28 m (3 sq. ft.); and
• b) be located in the exterior walls or through parts of skylights which are capable of being opened. BY-LAW NO. 2013-416 2) Despite subsection (1), an opening for natural ventilation is not required if mechanical ventilation is provided which changes the air once each hour. 3) Every room containing a water closet shall be provided with an opening or openings for natural ventilation located in an exterior wall or through skylights which are capable of being opened, and all such openings shall have a minimum aggregate unobstructed free flow area of 0.09 m (1 sq. ft.). 4) An opening for natural ventilation as required in subsection (3) may be omitted where a system of mechanical ventilation has been provided, such as an exhaust fan with a duct leading to outside the building. 5) Where mechanical ventilation is used, the ventilating duct which is on the exterior wall shall be located not less than 1.8 m (6 ft.) from a window located in an adjoining building. 6) The exterior exhaust ventilation ducts for commercial kitchens or restaurant kitchens shall be located not less than 3 m (10 ft.) from any skylight, window, ventilator, doorway or other opening located in an adjoining building and shall be directed in such a way as not to constitute a nuisance. BASEMENT, CELLAR OR UNHEATED CRAWL SPACE