Experts examined reduced pathogen transmission using a building’s original mechanical design, original installation, design intent, and proper maintenance in a new white paper.
Return Ductwork Requirement for Airborne Pathogens Through the Airstream, discusses two approaches: pressure barriers and airflow distribution. The paper looks at the pros and cons of using the cavity above a finished ceiling as a return air plenum combined with supply air to the air handler as a proper ventilation technique.
Considerations include how ventilation systems affect the health and well-being of building occupants. A ceiling plenum provides some fan-specific energy efficiency and reduced material and labor costs, but it could put occupants and workers at risk and result in unintended energy losses. An open ceiling plenum is difficult to clean and disinfect, while ductwork can be easily cleaned.
A ducted return system allows a testing, adjusting, and balancing professional to adjust room pressures and airflow patterns to accommodate a change in use or mitigate pathogen transmission during a pandemic. Authors of the white paper include members of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Technical Committee 5.2 Duct Design.