Current building code ventilation requirements in Canada are generally based on comfort and odour control, rather than illness prevention or reduction.Footnote 143 Commercial buildings are often built to meet a ventilation standard called ASHRAE 62.1. However, this doesn't provide enough clean air to address airborne illnesses,Footnote 144 and many older buildings are not even up to code.
Recent best-practice standards and guidelines for healthier indoor air include:
- ASHRAE 241 for airborne illnesses (free read-only copy here)
- ASHRAE 44 for wildfire smoke
Currently, following these standards in Canada is voluntary. There are many ways to improve the function of an existing HVAC system even if a building cannot comply with all aspects of the standards, such as:
- Using higher grade filters (e.g., MERV-13) if the system can handle them
- Adjusting outdoor air intake (increasing it to address airborne illnesses, reducing it to address wildfire smoke)
- Ensuring the system runs whenever the building is occupied, instead of switching off automatically at a target temperature
- Ensuring regular maintenance, including filter replacement
Learn more:
- Ventilation system guidelines | OSPE
- Find your provincial or territorial OHS regulations about minimum ventilation and air quality | Canadian Centre for Occupational Health and Safety (CCOHS)
Footnotes (2)
- WHO, Indoor Airborne Risk Assessment, 4. Back to text
- OSPE, Ventilation System Guidelines, 13; Joey Fox, “Equivalent Clean Airflow Rates from ASHRAE 241 Control of Infectious Aerosols (Part 2),” It's Airborne (blog), July 7, 2023, https://itsairborne.com/ashrae-241-control-of-infectious-aerosols-part-2-equivalent-clean-airflow-rates-76a511769d4d. Back to text