Video Presentations: The Cross-Contaminant Risk of Different Make-Up Air Options in Multi-Unit Residential Buildings

Duncan Phillips
Principal
RWDI, Ontario

People living in tall buildings share air with lots of other people in those residential spaces. We have seen outbreaks of disease in tall buildings in the past (e.g. SARS in Hong Kong) and are starting to see this in buildings across the world with COVID-19 (e.g. Calgary, Melbourne, Göttingen). For the recent outbreaks, it is not clear at this time whether the transmission routes are through the air or surfaces. Regardless, the ventilation system is one of the tools that can be used to protect people.

One of the issues in a tall building is how to provide adequate air into the individual units and maintain adequate ventilation in the common spaces (e.g. hallways, elevators, etc). Design practices in cities across the world use different approaches for ventilation in residential buildings. In Canada, unit-by-unit energy recovery ventilators (ERVs) are common (decentralized) while some cities in the United States provide ventilation via the corridors or directly to units (both centralized). All of these have consequences with respect to approaches to controlling smoke, stack effect, and various wind issues as well as transmission of airborne contaminants. Residents would be justified in thinking that opening their windows would increase ventilation, but in some cases, this can actually reduce outside air ventilation rates and increase transfer of air between units. Relative degrees of protection are compared (e.g. delivery of clean air) of a centralized vs. decentralized ventilation system in a moderately tall residential building through case studies.