Building ventilation & safety measures


Last updated: September 9, 2022



Heating, ventilation & air conditioning (HVAC) systems are important supporting systems that further ensure healthy indoor air quality.

Our teams continue to follow public health measures to ensure buildings are properly cleaned, operating, and maintained to provide a safe environment for students, faculty, and staff. The following public health measures continue to be the primary controls to effectively reduce transmission of COVID-19:   

  1. Receiving vaccination.
  2. Performing a daily health self-assessment and staying home if feeling ill.
  3. Practicing proper respiratory etiquette (e.g. cough into elbow).
  4. Practicing good hand hygiene.
  5. Regular environmental cleaning and disinfecting.


To ensure high prioritization of heating, ventilation and air conditioning (HVAC) issues in learning spaces (classrooms, lecture theatres, etc.), please call the Facilities Service Centre at 604.822.2173

The HVAC working group 

UBC established a COVID-19 Heating, ventilation & air conditioning (HVAC)  working group to review and consider implementation of technical recommendations to enhance building ventilation systems and reduce the risk of airborne infectious aerosol exposure in UBC owned and operated buildings. As the university prepares to resume on campus instruction and ensure a safe indoor environment, the working group has prioritized our campus teaching spaces.   

The working group team, which includes professional engineers and subject matter experts in the design, maintenance and operation of building mechanical systems included Facilities and Safety & Risk Services from UBC Vancouver, Campus Operations and Risk Management from UBC Okanagan, and Faculty from the School of Population & Public Health, Occupational and Environmental Health Division. 

There are numerous sources of information regarding ventilation and transmission. The working group principally consulted with the BC Centre for Disease Control (BCCDC), WorkSafeBC, and American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE)   

The reference sources consistently recommend an approach of:

  • Increasing air ventilation rates (both recirculated and fresh) while still maintaining comfortable indoor air temperature and humidity.   
  • Regular maintenance of building HVAC systems.   
  • Opening windows or doors where possible or feasible.  

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UBC’s HVAC approach 

The COVID-19 Heating, ventilation & air conditioning (HVAC) working group had many discussions around best practices and took a balanced approach providing practical solutions that will ensure safe building environments and can be effectively implemented based on the complexity and limitations of our campus buildings.

The below measures, in addition to already established operations and maintenance practices, will enhance the functionality of building HVAC systems to ensure a high standard of safety for students, faculty and staff at UBC. 


Measures implemented 
  • Increase ventilation on all main air handling units (AHU) with an additional 2 hours of pre- or post-occupancy flush of air, this will result in an additional three air exchanges per day. These air handling units serve all spaces within a building including classrooms, offices, lunchrooms, hallways, corridors, etc. AHU’s that serve laboratory spaces are designed to bring in 100 per cent of outdoor air and operate 24/7.
  • The current schedule of air handling units that are not scheduled to be on 24/7 the times that the building is primarily occupied mirror the times the units are on.
  • Outdoor air has been increased above American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE) design quantity during occupied hours; the level of increased outdoor air will depend on equipment design limitations to provide the best possible occupant comfort and humidity levels.
  • Highlight to occupants about where to open windows/doors.

Measures implemented
  • The majority of main AHU’s on campus are equipped with ASHRAE recommended MERV13 filters. Where mechanical system design allows, any filters that were not MERV13 have been upgraded. AHU's that are not designed to accommodate a higher filtration rating it is not advantageous to increase the MERV rating as the airflow will be restricted and the fan systems will deliver less air to the space which is counterproductive.
  • Building AHU filters are changed based operating context, inspection results, diagnostic readings and time-based replacements. We have a dedicated team of National Air Filter Association (NAFA) Certified Technicians that are certified NAFA Certified Technician Level 1 (NCT) trained professionals

Measures implemented
  • Physical inspections to ensure function of outdoor air dampers and HVAC controls on main air handling units.
  • Reviewed the feasibility of upgrading teaching spaces without mechanical systems (<5% of teaching spaces) by adding fans or portable filtration units to increase air in teaching spaces without mechanical ventilation.

Measures implemented

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Air exchange rates / Air changes per hour ACH

Building ventilation systems are designed for occupant health and comfort and take into account factors such as the space use, number of people that will occupy the space, and heating/cooling requirements.  Air exchange rates or air changes per hour (ACH) are generally not used as a principle design target except in special areas such as laboratories and animal care facilities, which have regulated ACH rates.

In addition to various other measures to improve ventilation to mitigate COVID-19 risk, experts on the ASHRAE pandemic task force recommended three equivalent ACH’s per hour. This is UBC’s minimum target. There are many factors that need to be considered to determine an equivalent ACH rate. The equivalent air exchange rate is based on the outside air volume and a pro-rated volume of return air which varies with filter efficiency.

The information required to perform ACH rate calculations include, but are not limited to room volume (cubic feet), volume of air delivered to the room (cubic feet per minute), volume of outside air (cfm), volume of return air (cfm) and filter efficiency (MERV rating).

UBC Vancouver campus has calculated the equivalent ACH rate on a subset of the 900+ teaching spaces on campus. Spaces were chosen to include factors such as building age, size and across a range of faculties. The calculations are as follows:

ACH equivalent o/a = ACH o/a + ACH filter
ACH filter = (ACH r/a) x (Filter Droplet Nuclei Efficiency)

Below are examples of calculated ACH results for teaching spaces:

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Types of spaces and recommendations for occupants

Teaching spaces: Classrooms and teaching labs


  • Updated September 6, 2022: Teaching Spaces evaluation summary [PDF]
  • The Heating, ventilation & air conditioning (HVAC) working group has created the Teaching Spaces evaluation summary of teaching spaces, and categorized the ventilation type for teaching spaces on the UBC Vancouver campus. This document is updated as teaching spaces get upgraded with additional measures.
  • Limited or no mechanical ventilated spaces have been upgraded with additional measures and/or have specific occupant instructions posted in the space. For questions, please contact the Service Centre at 604-822-2173.
Mechanically ventilated spaces: Spaces designed with mechanical or forced ventilation that is driven by fans or other mechanical equipment within a building.
  • UBC Facilities is maximizing outdoor air intake by increasing main air handling units above ASHRAE design quantity during occupied hours, the amount of increased outdoor air will depend on design limitations while providing the best possible occupant comfort and humidity levels. Where mechanical system design allows, main air handling units are equipped with MERV 13 air filtration.
  • UBC Facilities is operating HVAC systems for an additional two hours of pre or post occupancy flush, and reviewing the time of day main air handling units are scheduled to turn off and on and mirror them with the times the building is primarily occupied. Systems continue to run at low levels after hours.
  • Laboratories are designed with systems with no recirculated air and operate from 100% outside air.
  • Doors and windows should remain shut as much as possible to optimize the mechanical design.
Naturally ventilated spaces: Spaces that are designed to induce the flow of outside air into the building or room caused by wind or stack effect.  
  • Occupants should open windows and doors to bring in as much fresh air without compromising occupant comfort (temperature) or security.
  • If equipped, open up any designed vents, such as trickle vents or occupant-controlled louvers.
  • Do not leave windows open when you vacate the room or overnight as it may result in too much cold air, security risks and rodents entering the building
Non-mechanically ventilated spaces  with windows: Spaces without mechanical ventilation systems equipped with openable windows.
  • Occupants should open windows and doors to bring in as much fresh air without compromising occupant comfort (temperature) or security.
  • Do not leave windows open when you vacate the room or overnight as it may result in too much cold air, security risks and rodents entering the building.
Non-mechanically ventilated spaces without windows: Spaces without mechanical ventilation systems and are not equipped with windows or where windows don’t open.
  • Limit amount of time spent in space with more than one occupant.
  • Usually equipped with vents in doors or above doors, ensure clear of posters, furniture
  • Open doors in area as long as possible without compromising security.

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For questions regarding your building, please contact your Building Administrator. They will submit a request to the Service Centre on your behalf, or work directly with your Facilities Manager. If the matter is urgent or for emergencies, please contact the Service Centre at 604-822-2173.

For information on UBC’s Communicable Disease Prevention Framework  and UBC Campus Rules, please visit

For UBC’s latest response to COVID-19, please visit

For inquiries regarding COVID-19, campus return planning, and health and safety, please contact