Identifying air movement pathways in and around buildings and their consequences for indoor air quality

We cannot see it moving, and we can only feel it when the velocity is perceptible.  Pressure differential, thermal forces, and wind determine where and how air moves in and around a building. All buildings have unrecognised air movement pathways, often convoluted, and often unintentional, such as through penetrations in walls and floor.

When the pressure differential facilitates it, unrecognised flows through these convoluted pathways can carry contaminants generated in one part of a building, or adjacent to a building, to unanticipated locations within the building. This is particularly true in buildings that are mechanically ventilated with multiple systems, but it also occurs in small residential buildings. These flows can and do transport contaminants over large distances within a building, and they often go unrecognised.

Using a number of case studies spanning four decades of experience assessing indoor air quality problems, Brad will discuss the driving forces and illustrate how this occurs in buildings, the often surprising pathways, and the negative impacts that can result for building occupants. Techniques for assessing airflow will also be identified. 

About Brad

Brad Prezant, Affil.AIRAH, is a public and occupational health scientist and engineer with a focus on epidemiology, ventilation, and public health focus. He recently authored an AIRAH publication on ventilation to prevent COVID transmission in schools. He is a member of ASHRAE SPC 241, Standard to Address Mitigation of Airborne Infection Transmission.

Brad assesses buildings for ventilation, achieving optimal ventilation for minimising the transmission of infection, and is the only person in Australia currently using SF6 tracer technology to measure actual air changes per hour, a true performance test of ventilation systems.