Return Air Plenum
A return air plenum is a space within a building that is used to facilitate air circulation by providing a pathway for air to return to the heating, ventilation and air conditioning (HVAC) system 1. Return plenums can play a role in promoting environmental health, building health and building biology by helping to regulate indoor air quality. With a ducted return—instead of a ceiling or attic plenum—a testing, adjusting and balancing (TAB) technician has the capability to maintain the duct as well as adjust room pressures, modify airflow patterns and stay safe from exposure to biologically active pathogens within the airstream and on the surfaces around them 2. Besides providing a level of thermal control, return ducts also help avoid reducing building occupants’ immune responses by providing conditioned air at a controlled indoor temperature and relative humidity optimal for occupant health