COVID-19 Ventilation Strategy

Updated: March 25, 2022

Due to the airborne nature of COVID-19, Laurier has taken significant steps to update our ventilation to ensure the health and safety of students, faculty and staff.

Facilities Asset Management (FAM), with support from Safety, Health, Environment and Risk Management (SHERM), began making updates on the ventilation in the summer of 2020.

Laurier has been following the best practices in building design by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), which provides guidance on the control of COVID-19 in schools and universities. FAM and SHERM have reviewed this guidance along with guidance from provincial and federal health agencies.

What Has Been Done


Filtration has been increased from MERV 8 to MERV 13 in all buildings that have forced air systems. MERV 13 has been recommended by the American Society of Heating, Refrigeration, and Air Conditions Engineers (ASHRAE) and American Industrial Hygiene Association (AIHA). Both the CDC and Health Canada recommend the highest filter rating without affecting airflow; MERV 13 is the highest filter rating that can be installed without significantly affecting airflow in our systems. 


Ventilation and specifically increased outdoor air and air exchanges are far more important than filtration to reduce transmission risk of airborne viruses. Laurier has increased both in buildings that have forced air systems. In addition, Laurier is performing air flushing, one hour before and one hour after occupancy every day, to replace indoor air with outdoor air.


Laurier continues to conduct HVAC testing throughout Waterloo and Brantford campus buildings, insuring that the ASHRAE-recommended target ventilation rate of six air exchanges per hour is met. We are working with third-party contractors to verify that systems are being properly maintained and are operating optimally.

Controls are being adjusted to bring in the correct amount of outdoor air and provide the recommended air flow For some of our older building systems. Laurier is also installing permanent airflow monitoring units to conduct real-time measurements.

Focus on Prevention Practises

While filtration and ventilation play a role, our vaccination and face-covering policies, as well as staying home while sick, are more effective in reducing the spread of COVID-19.

Laurier will continue to follow public health guidelines as they evolve to keep faculty, staff and students safe.

Frequently Asked Questions

Can building air filtration protect me from getting COVID-19?

Filtration in building heating, ventilation, and air conditioning (HVAC) systems can be part of an overall risk mitigation approach, but is not generally regarded as a solution by itself.

There is no direct scientific evidence of benefit, but some reduced exposure can reasonably be inferred based on the ability of some filters to remove particles that contain a SARS-CoV-2 virus.

More importantly, in most buildings and in most situations, filters may be considerably less effective than other infection control measures including physical distancing, isolation of known cases, and hand washing.

Why haven’t HEPA filters been installed at Laurier?

There are several reasons why Laurier has not installed HEPA filters in our air filtration systems. The most important reason is that our systems were not designed to handle HEPA filters.

If we were to put HEPA filters in these units, the pressure drop would be so great that our rooms would no longer be getting the air exchanges needed to support staff and classes. The air would be clean, but the carbon dioxide levels would be much higher and the temperature would be too high in the summer or too low in the winter. Our HVAC units also cannot physically handle HEPA filters due to the increased size.

Commercial buildings are not designed to handle HEPA filters and Laurier systems are no different.

What about portable air cleaners?

Similar to building filtration, there is no direct clinical evidence of the benefit of portable air cleaners for reducing infectious disease risk, but some benefit can be reasonably inferred for appropriately sized (e.g. their removal rate is appropriate for the room), maintained, and operated portable HEPA filters.

As with building filtration, the details are important (e.g. efficiency and airflow rate of the air cleaner, sizing and placement within the space, maintenance and filter change, nature of space that is being cleaned), and appropriate portable filtration is only likely to be effective in concert with other measures.

At this time, SHERM is not recommending the use of portable HEPA filters in spaces served by an HVAC system. The data on the effectiveness of domestic units on the reduction of transmission is limited. These units are only truly effective if they are properly sized for the room, placed in a central location in the room, have the filters changed regularly, and are in a room with no HVAC system. If many units were running, the electrical demand would also become an issue.

Why shouldn’t I just use the highest-efficiency filter that I can find?

High-efficiency filters may be appropriate for your building, but they can also be counterproductive. The higher the MERV rating, the higher the resistance to allow proper airflow through the filter. A high-pressure drop filter can also diminish the amount of air supplied into the environment, making the filter less effective as well as causing other problems with other parts of the HVAC system.

Most importantly, the fan in the system may not run often and the efficiency of the filter will be less effective.

What about ionizers, ozone generators, plasma, and other air cleaning technologies?

None of these technologies have been proven to reduce infection in real buildings, even if they have promise based on tests in a laboratory or idealized setting. Some of them have substantial concerns about secondary issues (such as ozone production).