COVID-19 HVAC Best Practices

reduce virus transmission and air contaminants

The Centers for Disease Control has issued an updated “Interim Guidance for Businesses and Employers Responding to Coronavirus Disease 2019 (COVID-19), May 2020”.  An excerpt from this guidance related to HVAC system operation is provided below.

Consider improving the engineering controls using the building ventilation system. This may include some or all of the following activities:

  • Increase ventilation rates.
  • Ensure ventilation systems operate properly and provide acceptable indoor air quality for the current occupancy level for each space.
  • Increase outdoor air ventilation, using caution in highly polluted areas. With a lower occupancy level in the building, this increases the effective dilution ventilation per person.
  • Disable demand-controlled ventilation (DCV).
  • Further open minimum outdoor air dampers (as high as 100%) to reduce or eliminate recirculation. In mild weather, this will not affect thermal comfort or humidity. However, this may be difficult to do in cold or hot weather.
  • Improve central air filtration to the MERV-13 or the highest compatible with the filter rack, and seal edges of the filter to limit bypass.
  • Check filters to ensure they are within service life and appropriately installed.
  • Keep systems running longer hours, 24/7 if possible, to enhance air exchanges in the building space.

Note: Some of the above recommendations are based on the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) Guidance for Building Operations During the COVID-19 Pandemicexternal icon. Review these ASHRAE guidelines for further information on ventilation recommendations.

Click Here to see the full COVID-19 Guidance from the CDC.


The HVAC systems in most non-medical buildings play only a small role in infectious disease transmission, including SARS-CoV-2 (Coronavirus, COVID-19). However, transmission of SARS-CoV-2 through the air is still possible, so there are steps that should be taken to reduce airborne exposure. Changes to building operations, including the operation of heating, ventilating, and air-conditioning systems, can reduce airborne exposures.

Ventilation and filtration provided by heating, ventilating, and air-conditioning systems can reduce the airborne concentration of SARS-CoV-2 and thus the risk of transmission through the air. Unconditioned spaces can cause thermal stress to people that may be directly life threatening and that may also lower resistance to infection. In general, disabling of heating, ventilating, and air-conditioning systems is not a recommended measure to reduce the transmission of the virus.

HVAC filters, along with other strategies, help to reduce virus transmission while removing other air contaminants that may have health effects.

Read our complete statement on COVID-19 Best Practices


General HVAC system recommendations include:

  • Increase outdoor air ventilation (use caution in highly polluted areas); with a lower population in the building, this increases the effective dilution ventilation per person.
  • Disable demand-controlled ventilation (DCV).
  • Further open minimum outdoor air dampers, as high as 100%, thus eliminating recirculation (in the mild weather season, this need not affect thermal comfort or humidity, but clearly becomes more difficult in extreme weather).
  • Improve central air filtration to the MERV-13 or the highest compatible with the filter rack, and seal edges of the filter to limit bypass.
  • Keep systems running longer hours, if possible 24/7, to enhance the two actions above.
  • Consider portable room air cleaners with HEPA filters.
  • Consider UVGI (ultraviolet germicidal irradiation), protecting occupants from radiation,13 particularly in high-risk spaces such as waiting rooms, prisons and shelters.
  • Consider adding bipolar ionization to existing HVAC systems.

Please see our COVID-19 HVAC Best Practices document for additional information.


ASHRAE has compiled general information and best practices for different building types that can be accessed by following the links below:

Read Geauga Mechanical’s COVID-19 Best Practices for Schools


If you have specific questions about how these HVAC Best Practices can be applied to your facility, please reach out to your Geauga Mechanical Service Account Manager. We are here to help!

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