National Building Code of Canada: HVAC requirements

The National Building Code of Canada (NBC) is the model code on which most Canadian building regulation is based. It is published by the National Research Council of Canada (NRC) and developed by the Canadian Board for Harmonized Construction Codes. On its own, the NBC has no legal force. It becomes law only when a province, territory or municipality adopts it, with or without changes.

For HVAC designers, contractors and building owners, understanding how the NBC is organized makes it much easier to find the requirements that apply to a project, and to see why the answer often depends on the province. This guide gives an overview; it does not replace reading the code edition in force where you are building.

Editions and adoption

The NBC is updated on a roughly five-year cycle. The 2020 edition is the basis for most provincial codes currently in force, and the NRC released the 2025 editions of the national model codes around the turn of 2026. Provinces adopt new editions on their own timelines, often a year or more after publication, and frequently with amendments.

Some jurisdictions publish their own codes based on the NBC:

• Alberta: National Building Code - Alberta Edition.
• British Columbia: BC Building Code, with the City of Vancouver publishing its own Vancouver Building By-law.
• Ontario: Ontario Building Code, a regulation under the Building Code Act that follows the NBC's structure but has many differences.
• Quebec: Construction Code of Quebec, Chapter I, Building, based on the NBC with Quebec amendments.

Other provinces and territories generally adopt the NBC directly with limited amendments. See provincial building codes and HVAC for details on Alberta, BC and Ontario.

How the NBC is organized

The NBC is divided into three divisions:

• Division A: compliance, objectives and functional statements. It defines what the code is trying to achieve and allows alternative solutions.
• Division B: acceptable solutions, the technical requirements most people think of as "the code."
• Division C: administrative provisions.

Division B is organized into parts. The parts most relevant to HVAC are:

Plumbing is covered separately by the National Plumbing Code, fire safety in existing buildings by the National Fire Code, and energy efficiency for larger buildings by the National Energy Code of Canada for Buildings (NECB).

Part 3 versus Part 9 buildings

Which part applies depends on building size and occupancy. In general, Part 9 covers buildings of three storeys or less in building height with a building area not exceeding 600 m2, used for residential, business and personal services, mercantile, or medium and low hazard industrial occupancies. Everything else, and all assembly, care, treatment and detention occupancies, falls under Part 3, with HVAC governed by Part 6.

Part 6: heating, ventilating and air-conditioning

Part 6 is relatively short and largely performance based. It relies heavily on good engineering practice and referenced standards rather than detailed prescriptive rules. Key requirements include:

1. Design to good engineering practice. HVAC systems must be designed, constructed and installed in conformance with good engineering practice such as that described in ASHRAE handbooks and standards, HRAI manuals and SMACNA manuals.
2. Ventilation. Ventilation rates in Part 3 buildings are generally based on ASHRAE 62.1, as referenced by the code edition in force. See the ASHRAE 62.1 ventilation rate procedure.
3. Health care facilities. Ventilation for health care facilities references CSA Z317.2.
4. Contaminant control. Requirements for exhausting contaminants at the source, separating air from hazardous areas, and parking garage ventilation.
5. Ductwork. Duct materials, connections, clearances, insulation and access, including fire-performance requirements for duct materials and coverings.
6. Equipment installation. Clearances, access for maintenance, and requirements for fuel-fired appliances to comply with CSA B149.1 and refrigeration systems to comply with CSA B52.
7. Commercial cooking. Kitchen exhaust systems designed to NFPA 96.
8. Piping and chimneys. Requirements for hydronic piping, chimneys and vents.

Fire and smoke requirements affecting HVAC

Part 3 contains many of the provisions that most directly affect HVAC layout:

• Fire dampers where ducts penetrate fire separations required to have a fire-resistance rating, with specific exceptions.
• Smoke dampers in certain situations, such as some systems serving high buildings or interconnected floor spaces.
• Fire stop flaps at ceiling membrane penetrations in fire-rated assemblies.
• Shafts enclosing ducts that pass through floors.
• Fan shutdown on fire alarm activation for certain air handling systems, and smoke control measures in high buildings.
• Plenums requirements for combustibility of materials in return air plenums.

Dampers are required to be listed to CAN/ULC-S112 (fire dampers), CAN/ULC-S112.1 (leakage-rated dampers for smoke control) or CAN/ULC-S112.2 (fire stop flaps). See fire dampers and smoke control under Canadian codes.

Energy efficiency

For Part 9 buildings, Section 9.36 sets energy efficiency requirements for the envelope, HVAC and service water heating. For larger buildings, energy requirements come from the NECB or a provincially adopted alternative such as ASHRAE 90.1 or a step code. See NECB 2020 and HVAC compliance.

The 2020 code cycle introduced tiered energy performance levels in the NBC and NECB, allowing provinces to adopt progressively higher tiers over time on the path toward net zero energy ready construction.

Alternative solutions

Division A allows designers to propose alternative solutions that achieve at least the level of performance required by the acceptable solutions in Division B. Alternative solutions are common in complex projects, such as smoke control in atria, large data centres or unusual ventilation approaches. They require documentation showing how the objectives and functional statements are met, and acceptance by the authority having jurisdiction.

Practical tips for owners and designers

• Confirm which code edition and amendments apply on the date of permit application, not just the latest published version.
• Check municipal requirements, which may add to provincial codes, especially in Vancouver and Toronto.
• Read the explanatory notes in Division B, which often clarify intent.
• Coordinate early with the authority having jurisdiction on any alternative solutions.
• Engage a registered professional where required. See mechanical permits and engineering seals.

Key takeaways

• The NBC is a model code that becomes law only when adopted by a province, territory or municipality.
• HVAC requirements for larger buildings are mainly in Part 6, with key fire and smoke provisions in Part 3.
• Small buildings follow Part 9, including Sections 9.32, 9.33 and 9.36.
• Part 6 relies heavily on referenced standards such as ASHRAE 62.1, CSA Z317.2, CSA B149.1, CSA B52 and NFPA 96.
• Energy requirements for larger buildings come from the NECB or a provincial alternative.
• Always confirm the edition and amendments in force where the project is located.