Effect of Infectious Disease Risk Management on Indoor Environmental Quality in Lecture Rooms: Current Performance and Future Considerations

The global COVID-19 pandemic has resulted in significant and accelerated developments in ventilation practises, where the need to ventilate buildings has been put centre stage. Longer-term ventilation approaches are now more likely to utilise hybrid ventilation strategies to address the challenge of ensuring resilient indoor thermal environments that are carbon neutral while also minimising the risk of long-range airborne infectious spread of viral pathogens. In the short term, there are many existing buildings which may not undergo retrofit for some time, and consequently, risk mitigation strategies have been implemented in these buildings by utilising existing systems. This paper will present an indoor environmental quality evaluation of ten university lecture rooms both before, during and after changes in ventilation management behaviour and systems that were accelerated due to the COVID-19 pandemic. The results indicate a mean reduction in internal carbon dioxide levels of between 46% and 67% when pre-COVID-19 and COVID-19 datasets are compared and between 11% and 62% when pre-COVID-19 and post-COVID-19 datasets are compared. Changes in behaviour and systems have reduced the time spent above thresholds conducive to virus growth by between 8% and 54%, depending on the lecture room. Despite this, a “rebound” can be observed in many rooms, with CO 2 levels appearing to be trending toward pre-pandemic levels. This work indicates the effect of behavioural and system changes on ventilation and the potential risk for virus spread. The results indicate a need to retrofit existing lecture rooms with more advanced natural or mechanical systems to ensure consistent indoor environmental quality.