Engineering Strategies for Airborne Diseases

H V A C S Y S T E M S T R A T E G I E S

O5

CONTROL OF AIR DIRECTION - OVERHEAD DISTRIBUTION

The majority of buildings in the USA are served by forced air systems. These systems can have either overhead or underfloor distribution systems. With overhead distribution, the conditioned air enters the space from supply ducts/diffusers installed over the occupied zone. The return air exits via return air plenums or diffusers positioned in the ceiling or full height walls. Overhead air distribution is designed to mix the entire air volume in an enclosed space and the air will circulate for longer and then reach occupants.

Any suspended pollutants or particles will linger for greater periods of time, resulting in lower air quality.