Altura is committed to advancing our collective understanding of the role building systems, and specifically ventilation systems, play in confronting the infectious disease challenge we face today.
First and foremost, we recognize the guidance from CDC and WHO that emphasizes social distancing and isolation of at-risk populations as the primary mechanisms for slowing the spread of COVID-19 and protecting vulnerable populations. While building ventilation systems may play only a minor role, if any, in this overall equation, it is important to keep basic principles in mind as we all review operations and maintenance practices in light of the rapidly changing operating environment.
We offer the following summary points to consider:
- We are not aware of any research that supports changing building HVAC operation as an effective means of impacting the spread of a virus such as COVID-19. No standard air handling equipment can be guaranteed to be effective in filtering biological diseases. Altura can make no recommendation of a safe level of filtering or outside air rates to guarantee personal safety.
- Certain medical facilities are designed holistically to contain airborne pathogens. These systems require an integrated approach based on dedicated outside air supply, engineered exhaust rates, and precisely located supply and exhaust locations to draw airflow across critical care rooms in a predetermined direction. Simply changing a standard HVAC system to 100% outside air supply does not accomplish the effect of a space designed for medical care.
- Altura strongly recommends that outside air ventilation rates are being maintained at or above ASHRAE 62 minimum ventilation rates. Consistent outside air ventilation is often one of the first elements of air handling systems to be degraded during operations. If you have questions or concerns about your ventilation system meeting ASHRAE and other local ventilation standards, please don’t hesitate to contact Altura for assistance.
RESOURCES AND FURTHER DISCUSSION
ASHRAE have published an online repository of information regarding air handling equipment and infectious disease available at: https://www.ashrae.org/technical-resources/resources
Notably as of 3/17/2020 none of the recommendations on the ASHRAE website or its linked resources include modifications to the operation of air handling equipment.
It is always best practice to maintain air filtration per the original equipment design. Changing air filters at appropriate pressure differential is recommended to avoid damage to filter banks or reduced air quality from bypassing filter banks. Substitution of the originally specified air filters with higher efficiency filters can cause air flow and unit capacity to be reduced if not selected properly. It is best to consult a mechanical design engineer before substituting a higher efficiency air filter. ASHRAE positions on filtration and sterilization technologies are available on their website. (1)
While maintenance of existing systems is not currently believed to have a potential for exposure to maintenance personnel, out of an abundance of caution you may wish to avoid unnecessary maintenance of air distribution systems until such time as the outbreak is contained.
Medical air handling equipment are the only systems designed for the containment of airborne pathogens. Even in a medical environment, limited to no studies of filtration or disinfection of air streams have been conducted (2). No conventional air handling equipment can be guaranteed to be effective in filtering biological diseases. Altura can make no recommendation of a safe level of filtering or outside air ventilation rates to guarantee personal safety.
RESOURCES AND FURTHER DISCUSSION
ASHRAE published a memo on building operation during the COVID-19 epidemic available at:
The recommendations underscore the value of always maintaining effective ventilation rates and appropriate filtration.