HPAC Magazine

ASHRAE updates Building Readiness Guide

“New information includes the theory behind the use of equivalent outdoor air supply, method for calculating the performance of filters and air cleaners in series, and filter droplet nuclei efficiency that help evaluate the systems’ ability to flush the building.”

February 3, 2021   By HPAC Magazine

ashraeThe ASHRAE Epidemic Task Force has updated its reopening guidance for HVAC systems in buildings to help mitigate the transmission of SARS-CoV-2.

“The Building Readiness Guide includes additional information and clarifications to assist designers and commissioning providers in performing pre- or post-occupancy flush calculations to reduce the time and energy to clear spaces of contaminants between occupancy periods,” said Wade Conlan, ASHRAE Epidemic Task Force Building Readiness team lead, in a media release.

“New information includes the theory behind the use of equivalent outdoor air supply, method for calculating the performance of filters and air cleaners in series, and filter droplet nuclei efficiency that help evaluate the systems’ ability to flush the building.”

Major updates to the guidance includes:

  • Pre- or Post- Flushing Strategy Methodology: The strategy has been updated to include the use of filter droplet nuclei efficiency, which is the overall efficiency of filter based on viable virus particle sizes in the air, to assist in determining the impact of the filter on the recirculated air on the equivalent outdoor air.
  • Flushing Time Calculator:  There is now a link to a view-only Google Sheet that can be downloaded for use, to help determine the available equivalent outdoor air changes and time to perform the flush.  
  • Heating Season Guidance:  the guide now includes data to consider for heating of outdoor air and the potential impact on pre-heat coils in systems.
  • Adjustments to Align with Core Recommendations: The Core Recommendations were released in the last month and this guidance document needed to be updated to ensure that the information provided aligned with the intent of those recommendations. This included minimum outdoor air supply and filter efficiency requirements and their role in an equivalent outdoor air supply-based risk mitigation strategy.

 The guidance addresses the tactical commissioning and systems analysis needed 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 ashrae.org/COVID-19.

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