A season with an override
Section 6(1) requires every landlord to ensure each rental unit "is provided with Adequate and Suitable Heat between the 15th day of September in each year and the first day of June of the following year, or as ordered by the Director of Enforcement and By-law Services pursuant to Section 15 of this By-law and posted on the City of Brampton website".
That override is rare and it matters operationally. In every other municipality on this site the season is fixed in the text; in Brampton a cold spell outside the default window can be brought inside it by an order, and the notice of that order lives on the City's website rather than arriving in your post.
The practical consequence is that a Brampton landlord cannot set the boiler schedule once and forget it. If you operate here, the City's enforcement page is a thing to check in early June and early September rather than a thing to read once.
The measurement is specified precisely
The definition fixes both the number and the method: a minimum air temperature "of twenty (20) degrees Celsius at one and one-half (1.5) metres from above floor level and one (1) metre from exterior walls in all habitable space and in any area intended for normal use".
"Any area intended for normal use" reaches past habitable rooms — a reading taken only in the living room is not the test the bylaw sets.
Section 5 frames the whole instrument: every landlord shall provide vital services for rental units as provided for in the by-law. Heat is one of several obligations in it rather than a standalone rule.