COVID-19 has triggered building owners and managers to focus intently upon Indoor air quality. How safe is your building? What assurances can you provide to occupants or future occupants that spaces are safe?

The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) published an article on managing the risk of spreading the virus through HVAC systems. These guidelines created by ASHRAE have been effective in mitigating pathogens and viruses prior to COVID-19 but are now much more relevant to the general public.

By following these guidelines, building owners can establish an action plan and/or establish a baseline of understanding and mitigating the spread of the virus and other unhealthy particles.

Not only do these measures promote better health, but our previous article also discusses the benefits of employee performance when delivering clean, fresh air to work areas.

    • Consider designs that promote cleaner airflow patterns by exhausting airborne particulates.
    • Use airborne infection isolation room (AIIR) anterooms in high-risk environments.
    • Employ enhanced filtration in occupant-dense spaces.
    • Install specialized UV lighting.
    • Use local exhaust ventilation for source control.
    • Use high efficient particle filtration in centralized HVAC to reduce the airborne load.

Healthcare buildings should have the following design and operation methods:

    • Capture expiration aerosols with headwall exhaust, tent, snorkel with exhaust, floor-to-ceiling partitions with door supply and patient exhaust, local air HEPA-grade filtration
    • Exhaust bathrooms and bed pans
    • Maintain temperature and humidity as applicable to the infectious aerosol of concern
    • Deliver clean air to caregivers
    • Maintain negatively pressurized intensive care units (ICU) where infectious aerosols may be present
    • Provide 100% exhaust of patient rooms
    • Use ultraviolet germicidal irradiation (UVGI)
    • Increase the outdoor air change rate
    • Establish HBAV contribution to a patient room turnover plan before preoccupancy

Non-healthcare buildings should consider the following modifications to building HVAC systems to plan for an emergency response:

    • Increase outdoor air ventilation
    • Improve central air and other HVAC filtration to MERV-13 or the highest level achievable
    • Keep systems running for longer hours
    • Add duct- or air handling unit-mounted, upper room, and/or portable UVGI devices in connection to in-room fans in high-density spaces
    • Maintain temperature and humidity as applicable to fight infectious threats such as COVID-19
    • Bypass energy recovery ventilation system that leak potentially contaminated exhaust air back into the outdoor air supply.

“Design engineers can make an essential contribution to reducing infectious aerosol transmission through the application of these strategies,” the document notes. “Managing indoor air to control distribution of infectious aerosols is an effective intervention which adds another strategy to medical treatments and behavioral interventions in disease prevention.”

VCA Green provides a variety of third party consultation services related to verifying ASHRAE ventilation standards and other best practices. For more information on how to optimize the air quality in your new or existing building, contact Moe Fakih below.

Contributing Writer: Albert Luu

Moe Fakih, Principal



  • ASHRAE Board of Directors. 2020. ASHRARE Positions Documents on Infectious Aerosols