Is it possible to ‘pandemic proof’ your HVAC systems?

The short answer to this question is “no!” There are too many variables to uncover — the infectious dose of SARS-CoV-2, the virus that causes COVID-19, is still unknown — or consider, such as the various modes of virus transmission. However, as our industry recovers from the effects of COVID-19, we highly recommend preparing ourselves, our systems and our buildings for the next epidemic. The first step for heating, ventilating and air conditioning (HVAC) systems is preparing a building readiness plan by reviewing the systems and equipment to mitigate the transmission of pathogens.

The World Health Organization (WHO), Centers for Disease Control and Prevention (CDC) and other health authorities believe COVID-19 is mainly transmitted by short-range large droplets. The CDC states that transmission by aerosols (droplet nuclei) is uncertain and airborne transmission is unlikely, but the WHO states that airborne transmission might be possible. The current research offers mixed results regarding airborne transmission. ASHRAE’s position indicates that to control the impact of this virus, “transmission of SARS-CoV-2 through the air is sufficiently likely that airborne exposure to the virus should be controlled.” The risk of airborne or aerosol transmission can be reduced by HVAC systems by reducing the airborne concentration, such as through increased ventilation and air management, filtration and air cleaning.

Conducting an HVAC risk assessment to create an HVAC systems operational plan will help mitigate virus transmission, monitor systems’ performance and record any adjustments to operate the systems during the pandemic. The analysis includes assessing outside air ventilation, filtration levels, developing an air cleaning strategy (like ultraviolet energy), reviewing the systems’ operating hours and assessing the building automation systems’ capabilities. In addition, the readiness team should create work orders to correct issues with the systems and ensure preventative maintenance is completed. During this process, we document pre-correction, post-correction and post-event operation and airflows and work with our customers to develop a building readiness plan, which will hopefully help them occupy their buildings today and identify methods to future-proof their buildings.

As we complete the risk assessment with our clients, we verify that they understand the various modes of operation (e.g., shutdown, preoccupancy, partial and full occupancy and epidemic or post-epidemic) and work with them to provide training for their tenants on safety measures. As they prepare to reoccupy the building, we recommend that they flush it with outside air for at least four hours, then operate the HVAC systems for 24 hours prior to occupancy and review the systems’ trend data. We also recommend that the water systems are flushed to avoid contamination and check various water systems for appropriate levels of water treatment. It is also important to verify the supply chain to obtain needed HVAC parts. And do not forget to update your systems manual to have a record of what was done and how the systems should operate.

We hope to never have to worry about another epidemic or pandemic; however, looking at the Council on Foreign Relations’ article, “Major Epidemics of the Modern Era,” there have been several epidemics and pandemics in the past two decades.

While it is not possible to “pandemic proof” your HVAC systems, these steps can help you mitigate potential problems.

For more information, contact Bill Bradford at or Wade Conlan at

Posted on June 11, 2020