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.
“The Building Readiness Guide includes additional information and clarifications so that owners can avoid operating their HVAC systems 24/7,” says Wade Conlan, ASHRAE Epidemic Task Force Building Readiness Team lead in a press release. “By rolling out this updated guidance, we are providing 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- Occupancy with Outdoor Air
The intent of this strategy is to ensure that 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 percent. 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 (ERV) 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.