PART 9 — HOUSING AND SMALL BUILDINGSUpdated for the 2024 Ontario Building Code
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9.32.2.3.Non-Heating-Season Mechanical Ventilation
(1) Where a habitable room or space is not provided with natural ventilation as described in Article 9.32.2.2. and is
mechanically cooled, its non-heating-season mechanical ventilation system shall
(a) have the capacity to exhaust air from inside the room or space, or to introduce outdoor air into that room or space, at
a rate conforming with Table 9.32.2.3., or
(b) comply with Subsection 9.32.3.
(2) In applying Clause (1)(a),
(a) at least one bedroom in each dwelling unit shall be designated as the master bedroom,
(b) air change rates for any combined living/dining or family/dining space shall be determined as if the spaces were
individual rooms,
(c) where a basement incorporates rooms of the types designated in Table 9.32.2.3., the assigned air change rate for
each room shall be as specified for those types of rooms,
(d) basement areas used for other purposes that exceed 2/3 of the total basement floor area shall be assigned an air
change rate of 10 L/s,
(e) basement areas used for other purposes that are 2/3 of the total basement floor area or less shall be assigned an air
change rate of 5 L/s, and
(f) other habitable rooms, other than spaces intended solely for access, egress, storage, or service equipment, shall be
assigned an air change rate of 5 L/s.
(3) Where a habitable room or space is not provided with natural ventilation as described in Article 9.32.2.2. and is not
mechanically cooled, the non-heating-season mechanical ventilation system shall have the capacity to exhaust indoor air
from the room or space or to introduce outdoor air to that room or space at a rate of one air change per hour.
(4) A non-heating-season mechanical ventilation system shall be designed and installed in conformance with good
practice such as that described in the ASHRAE Handbooks and Standards, the HRAI Digest, the Hydronics Institute
Manuals and the SMACNA Manuals.
Table 9.32.2.3.
Air Change Rate
Forming Part of Clause 9.32.2.3.(1)(a)
Room or Space Rate, L/s
Master bedroom 10
Other bedrooms 5
Living room 5
Dining room 5
Family room 5
Recreation room 5
Basement 10
Kitchen 5
Bathroom or water closet room 5
Laundry room 5
Utility room 5
Other habitable rooms 5
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
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Code text is reproduced for reference from the Ontario Building Code (O. Reg. 163/24, 2024 Building Code Compendium). This page is provided for general information and is not an official copy. Always verify requirements against the official Ontario Building Code and confirm with your local building department.