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ASHRAE epidemic task force releases updated building readiness guide

The ASHRAE Epidemic Task Force has updated its reopening “Building Readiness” guidance for HVAC systems to help mitigate the transmission of COVID-19.

“The Building Readiness Guide includes additional information and clarifications so that owners can avoid operating their HVAC systems 24/7,” said Wade Conlan,  ASHRAE Epidemic Task Force Building Readiness Team lead. “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%.

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.
  • Building Readiness Modes of Operation for the Building: These should include the following:
  • Epidemic Operating Conditions in Place (ECiP)
  • Occupied- at pre-epidemic capacity
  • Occupied- at reduced capacity or Unoccupied temporarily
  • Operation during building closure for indefinite periods
  • Post-Epidemic Conditions in Place (P-ECiP)
  • 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 systems ability to mitigate virus transmission.

To view the complete ASHRAE Building Readiness guide and other COVID-19 resources, visit

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