For those reopening buildings, ASHRAE updates ventilation and occupancy guidelines so you can avoid running your HVAC 24/7

by Brianna Crandall — September 7, 2020 — As many buildings are preparing to reopen during this pandemic, global building technology society ASHRAE’s Epidemic Task Force has updated its reopening Building Readiness guidance for heating, ventilation and air-conditioning (HVAC) systems to help mitigate the transmission of the SARS-CoV-2 coronavirus that causes COVID-19.

Wade Conlan, ASHRAE Epidemic Task Force Building Readiness Team lead, explained:

The Building Readiness guide includes additional information and clarifications so that owners can avoid operating their HVAC systems 24/7. By rolling out this updated guidance, we are hoping to provide a more robust structure for building owners to complete the objectives of their Building Readiness Plan and anticipate the needs of building occupants.

Specific updated recommendations to the building readiness guidance include the following:

  • Pre- and Post- Flushing Strategy: The intent of this strategy is to ensure the ventilation assists in removing bioburden during, pre-, and post- occupancy of the building. The building is flushed for a duration sufficient to reduce concentration of airborne infectious particles by 95%. For a well-mixed space, this would require three air changes of building volume based on outside air cfm (or three equivalent air changes including the effect of filtration and air cleaners), as detailed in the calculation methodology.  There is also some guidance on methods to potentially increase the quantity of outdoor air introduced by systems.
  • Energy Recovery Ventilation (ERV) Systems Operation: This helps determine if your energy wheel is well designed and/or well maintained and whether it should remain in operation. Keep in mind that if any issues are fixed, it could be reengaged. Helpful links and information to the ERV Guide will help owners and facilities managers (FMs) determine if their energy wheel should remain in operation.
  • Building Readiness Modes of Operation for the Building: These should include the following:

As with the previous version, the updated guidance still addresses:

  • Tactical commissioning and systems analysis to develop a Building Readiness Plan;
  • Increased filtration;
  • Air-cleaning strategies;
  • Domestic and plumbing water systems; and
  • Overall improvements to a system’s ability to mitigate virus transmission.

To view the complete ASHRAE Building Readiness guide and other COVID-19 resources, visit the ASHRAE website. Founded in 1894, ASHRAE is a global professional society committed to serve humanity by advancing the arts and sciences of heating, ventilation, air-conditioning, refrigeration (HVAC/R) and their allied fields through research, standards writing, publishing, certification and continuing education.