A systematic review on COVID-19 related research in HVAC system and indoor environment

The on-going COVID-19 pandemic has wrecked havoc in our society, with short and long-term consequences to people's lives and livelihoods - over 651 million COVID-19 cases have been confirmed with the number of deaths exceeding 6.66 million. As people stay indoors most of the time, how to operate the Heating, Ventilation and Air-Conditioning (HVAC) systems as well as building facilities to reduce airborne infections have become hot research topics. This paper presents a systematic review on COVID-19 related research in HVAC systems and the indoor environment. Firstly, it reviews the research on the improvement of ventilation, filtration, heating and air-conditioning systems since the onset of COVID-19. Secondly, various indoor environment improvement measures to minimize airborne spread, such as building envelope design, physical barriers and vent position arrangement, and the possible impact of COVID-19 on building energy consumption are examined. Thirdly, it provides comparisons on the building operation guidelines for preventing the spread of COVID-19 virus from different countries. Finally, recommendations for future studies are provided.