The standard, basic COVID-19 preventative measures, including self-screening, physical distancing, use of non-medical mask or face covering, surface cleaning, and disinfection and hand washing are key to prevention and mitigation. There is not one public health measure that can guarantee protection from COVID-19; multiple strategies are needed. 

COVID-19 has not changed code or regulatory requirements for ventilation in workplaces. Consistent with the hierarchy of health and safety controls and the precautionary principle, public health agencies and industry organizations have developed guidelines for building ventilation during the pandemic.

This tri-campus HVAC strategy includes several measures (listed above under ‘implementing ventilation measures across our campuses’ and ‘classroom-specific additional control measures during the pandemic’), that are being implemented by professional engineering and technical staff with the expertise required to interpret guidelines in relation to the variety and complexity of buildings and systems on our campuses. These guidelines have also been applied to U of T residences. 

The HVAC strategy focuses on verifying that systems are being properly maintained and operating accordingly, adjusting controls for parameters such as the amounts of total air and outdoor air where feasible, and upgrading filtration where feasible with the existing infrastructure. 

Like many other large educational institutions, we have a variety of buildings and systems. Modifications and upgrades depend on the building and system under consideration. For example, in heritage buildings, renovations and system changes may not be allowed. 

In spaces that do not have mechanical ventilation, where possible, open windows and doors and continue encouraging users to follow public health recommendations: vaccination, mask use, staying home when you are sick, finding alternatives for higher-risk activities where appropriate (for example, virtual participation in events), regular disinfection and increased hand hygiene. Many tasks at the University, such as general office activities or other administrative tasks confer a lower risk of transmission of COVID-19 compared to higher-risk workplaces such as healthcare settings where aerosol-generating medical procedures take place, for example. 

Supplemental air cleaners or air purifiers may be useful as a supplement to HVAC ventilation or if there is no outdoor air exchange. The transient nature of the population using and passing through classrooms results in greater numbers and density of people indoors compared to other spaces. As a result, an HVAC assessment of classrooms is being conducted with a target ventilation rate of six equivalent air changes per hour (ACH). Supplemental air filtration with HEPA filters will be installed in classrooms that cannot meet the target of equivalent six ACH. These HEPA filters can remove at least 99.97% of airborne particles as small as 0.3 microns and will be used to supplement the equivalent air change rate required to meet the target. The units will be managed and maintained by facilities and appropriate operational staff.

Despite significantly reduced building occupancy since the start of the pandemic, most of the HVAC systems were not completely shut off and have remained in operation. Filters have been regularly replaced based on best practices. 

Building operators continue to perform the following inspections and maintenance: 

• Ensuring filters have been replaced based on best practices. 
• Ensuring all setbacks and setup modes are set to normal. 
• Ensuring that fans are working and that air is moving in and out of the building. 
• Ensuring that dampers (outside and return) are working properly to help ensure the flow of fresh air to the building. 
• Ensuring that filters are operating appropriately. 

• Conducting an HVAC assessment on classrooms. 
• Installing air purifiers with HEPA filters in classrooms with less than six equivalent air changes per hour. Disabling demand-control ventilation to increase the amount of fresh air. 
• Performing air flushing two hours before occupancy every morning in every building to replace indoor air with outdoor air.

The University’s HVAC Strategy was based on a review of and alignment with relevant legislative requirements and credible industry guidelines, including Public Health Ontario, the Ontario Building Code, the Centre for Disease Control and Prevention (CDC) and the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). 

ASHRAE is the CDC’s and Ontario’s primary authority on HVAC, and it has published COVID-19 guidelines for the industry. ASHRAE does not consider increased ventilation rate (ACH) and percentage of outdoor air circulation as processes that clearly reduce the risk of transmission in non-healthcare facilities. U of T’s facilities groups have also worked with units to align HVAC operating hours with occupancy. In the event of an emergency, ASHRAE recommends flushing of a space with as much outside air as possible for extended amounts of time. The University defines an emergency in the context of COVID-19 as an outbreak on campus. In the event of an outbreak on campus, the University will follow the recommendations of ASHRAE and local public health authorities. 

In the event of an emergency, ASHRAE recommends upgrading central air filtration to MERV-13 or the highest compatible with the filter rack. Having a compatible filter in place is critical to ensure that filter edges are sealed to limit air bypass. 

All newer buildings and HVAC systems on-campus already use MERV-13 filters as the minimal standard for central air handling units. As a proactive measure, the University has replaced MERV-8 filters with MERV-13 filters or higher, wherever compatible with the existing infrastructure. In all cases, building operators are ensuring that filters are in good operating condition, clean and with sealed edges.

Brief interactions such as passing someone on the stairwell do not confer a material risk in the transmission of COVID-19. In addition, as outlined in the COVID-19 caretaking tri-campus strategy, high-touch surfaces such as railings and door handles will be disinfected daily, and sanitizing supplies are available in high-traffic areas. The use of a medical mask in high-density indoor spaces when physical distancing is not possible is strongly encouraged.