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Here's the NBC. I can't get my latest Alberta code to open right now to see if there's been any recent revisions but this should give you a starting point. They've switched to a FileOpen authorization system that rarely works.

9.33.6.11. Warm-Air Supply Outlets
1) In a dwelling unit, a warm-air supply outlet shall be provided in each finished
room that is located adjacent to unheated space.
2) Except as provided in Sentence (3), when a room described in Sentence (1) is
located adjacent to exterior walls, such outlet shall be located so as to bathe at least
one exterior wall or window with warm air, except in bathrooms, utility rooms or
kitchens, where this may not be practical.
3) Where the heating system is also designed to provide ventilation air, ceiling
outlets or outlets located high on interior walls are permitted to be installed, provided
the outlets are designed for this purpose and are installed with diffusers.
4) At least one warm-air supply outlet shall be provided for each 40 m2 of floor
surface area in unfinished basements serving dwelling units, and it shall be located so as
to provide adequate distribution of warm air throughout the basement.
5) At least one warm-air supply outlet shall be provided for each 80 m2 of floor
surface area in heated crawl spaces serving dwelling units, and it shall be located so as
to provide adequate distribution of warm air throughout the crawl space.
6) Except for pipeless furnaces, the capacity of warm-air supply outlets serving
dwelling units shall be not less than the design heat loss from the area served and shall
not exceed 3 kW per outlet.
7) In basements and heated crawl spaces, the calculated heat gain from the supply
ducts and plenum surfaces is permitted to be considered in calculating the design heat
loss.
8) The temperature of supply air at warm-air supply outlets shall not exceed 70°C.
9) Warm-air supply outlets located in finished areas shall be provided with
diffusers and adjustable openings and shall not be located on a furnace plenum.
10) A crawl space shall not be used as a warm air plenum.