As many buildings are preparing to reopen during this pandemic, the ASHRAE Epidemic Task Force has updated its reopening “Building Readiness” guidance for HVAC systems to help mitigate the transmission of SARS-CoV-2.
Specific updated recommendations to the building readiness guidance include the following:
Pre- and post-occupancy with outdoor air: The intent of this strategy is to ensure infectious aerosol in the building at the end of occupancy is removed prior to the next occupied period. 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 (three times the building volume) of outdoor air (or three equivalent air changes including the effect of filtration and air cleaners) as detailed in the calculation methodology. There is also guidance on methods to increase the quantity of outdoor air introduced by systems.
Energy recovery ventilation systems operation: Guidance is provided to assist in determining if an energy recovery system using an energy wheel is well designed and maintained and whether it should remain in operation. Based on the assessment of ERV conditions, it may be possible to fix problems and return it to service.
Building readiness modes of operation for the building: These should include the following:
Epidemic operating conditions in place
- Occupied- at pre-epidemic capacity
- Occupied- at reduced capacity or unoccupied temporarily
- Operation during building closure for indefinite periods
Post-epidemic conditions in place
- Prior to occupying
- Operational considerations once occupied
The guidance still addresses the 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 learn more, visit ashrae.org/COVID-19.
