Abstract

Throughout human history, nothing has killed more people than infectious diseases. Natural pandemics are ever-present and the next pandemic is a matter of ‘when’, not ‘if’. The event frequency for pandemics caused by natural and synthetic pathogens are likely to increase due to human encroachment into natural environments, bio-terrorism threats, high population density urban settings, lifestyles, and global connectivity. Covid-19 has clearly demonstrated the lack of understanding of airborne disease transmissions: we have been caught responding too late to the situation, and there is an urgent need to develop fundamental understandings and improve preparedness at all levels (Bhagat et al. 2020; Bhagat & Linden 2020; Burridge et al. 2021).

Essentially, indoor airborne disease transmission is a fluid dynamics problem; the formation of potentially contagion laden droplet/bio-aerosols is an interfacial flow problem and their subsequent transport in the indoor environment is a building ventilation flow problem. Dealing with Covid-19 has clearly demonstrated the need for a better understanding of these problems and, most importantly, dissemination of existing knowledge for their real-world application (Bhagat et al. 2020; Bhagat & Linden 2020). We all accept the need for higher ventilation rates to reduce the risk of transmission; however, tension prevails between working towards greater energy efficiency, achieving net-zero, and meeting ventilation needs.

Most of the buildings where we will live in the coming decades have already been built; in my presentation, I will show how field experiments allow us to understand these buildings. The work we have done and the solutions we have proposed – for example, how to ventilate makeshift hospitals in extremely resource and time limiting situations (Bhagat & Linden 2020) – are relevant for retrofitting existing buildings in order to create a resilient and sustainable built environment. I will talk about window types and how they influence ventilation. I will present our recent work on the relative importance of wind and buoyancy-driven natural ventilation.