March 4, 2021

ASHRAE Updates Building Reopening Guidance for HVAC Systems during COVID-19

New updates to ASHRAE’s “building readiness” document (PDF) address guidance for heating, ventilating, and air conditioning (HVAC) systems intended to help mitigate the transmission of SARS-CoV-2 as buildings reopen during the COVID-19 pandemic. The ASHRAE Epidemic Task Force, which updated the guidance, has added information related to the pre- and post-flushing strategy that is meant to help reduce the time and energy needed to clear indoor spaces of contaminants between periods of occupancy. The updated guidance includes a link to a downloadable “Equivalent Outdoor Air Calculator,” which is intended to be used to determine the available equivalent outdoor air changes and time required for a pre- or post-occupancy flush. According to Wade Conlan, the ASHRAE task force team lead, the guidance now includes information on “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.”

ASHRAE has also added data to consider for the heating of outdoor air and requirements for minimum outdoor air supply and filter efficiency.

Building owners and operators will find guidance related to the development of a building readiness plan, increased filtration, air-cleaning strategies, domestic and plumbing water systems, and system improvements to mitigate virus transmission.

The complete building readiness guide is available as a PDF. Other COVID-19 response resources from ASHRAE, the American Society of Heating, Refrigerating, and Air-Conditioning Engineers, are collected on the society’s website.