The Ontario Building Code | Indoor Design Temperatures
9.33.3.1. Indoor design Temperatures
(1) At the outside design temperature, required heating facilities shall be capable of maintaining an indoor air temperature of not less than,
(a) 22°C in all living spaces,
(b) 22°C in unfinished basements, and
(c) 15°C in heated crawl spaces.
In Plain Language
Indoor design temperatures used for heating system sizing calculations are set out in this article.
This is a plain-language summary of the 2012/2017 Ontario Building Code text above, for general understanding only and not a substitute for the Code. Always confirm current requirements against the 2024 edition (O.Reg. 163/24) or a qualified professional before construction.