HVAC for Dwelling Units

NEW for the 2024 OBC:

Section 9.32. Ventilation has been reorganized and expanded.

  • Houses are no longer categorized as Type I, Type II etc. 
  • Ventilation requirements have been split into “heating season ventilation” and “non-heating season ventilation” (see 9.32.2. and 9.32.3.)
  • Prescriptive requirements for make-up air are now provided (see 9.32.3.8.)
  • An additional 15 pages of appendix notes have been added showing acceptable arrangements of equipment for different mechanical ventilation approaches. (See multiple appendix notes starting with A-9.32.1.2.(2))

NEW for the 2024 OBC:

Section 9.33.Heating and Air Conditioning has been expanded.

  • Residential duct system requirements previously found in 6.2.4. are now in 9.33.
  • Additional requirements for radiators and convectors, chimneys, piping and refrigeration systems are also found in 9.33.
  • Ducts serving a dwelling unit in a house with a secondary suite are specifically prohibited from serving any other part of the house. (see 9.33.1.1.(3))


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