Healthy and resilient HVAC design for public buildings in post COVID-19 pandemic era

Abstract

People spend around 90% of their lifetime in buildings that serve important physiological, psychological and social functions, especially when considering public and occupants' health. 1,2 Public buildings, such as offices, hospitals, schools, shopping malls, hotels and transportation spaces, are places where people carry out various public activities with relatively large amounts of space and high flows of people, which can easily lead to airborne disease transmission. The outbreak of COVID-19 since 2019 has raised intense focus on the indoor air quality in these public buildings. Even if the COVID-19 pandemic is at an end as announced by the World Health Organization (WHO), 3 conventional heating, ventilation and air conditioning (HVAC) systems in public buildings are still not capable of coping with potential future severe epidemic situations, and a resilient HVAC would be needed to provide a meaningful retrofit measure to cope with the future epidemics. [4][5][6][7] Back in 2012, the UN responded to natural disaster risk management by referring to the concept of 'resilience', 8,9 which referred to the ability of a system to predict, absorb, adapt and recover from changes in events in a timely and effective manner while retaining its basic structure and function. 10 With reference to this definition, the concept of 'resilient HVAC' was proposed during the pandemic of COVID-19 to develop healthy and energy-efficient HVAC systems for buildings, which aimed to increase the adaptability of buildings in response to this disease. 11 In the post-pandemic period of COVID-19, when public buildings encounter similar public health emergencies, HVAC systems should be able to timely, quickly and reasonably transform into an emergency state to cope with challenges. Flexible design and construction of these HVAC systems by considering both peacetime and epidemic periods will be an important new development direction.This special issue is a continuation of the Special Issue that was published in June 2022. 4 The special issue addresses the issues of ventilations, HVAC, distribution of airborne and droplet transmissions, restriction control to prevent the spread of COVID-19, community settlement in response to COVID-19 and effects on learning. This editorial paper focuses on the problems of HVAC systems and the resilience of HVAC systems in response to epidemic/pandemic episodes.