Achieving suitable airflow rate in New Zealand classrooms: a CFD approach to inform on potential retrofitting solutions

During the COVID-19 pandemic, besides sanitising, masking, and increasing social distancing, opening classroom windows was the NZ Ministry of Education's main requirement for reopening schools. However, a pre-COVID-19 survey showed that only a third of the NZ teachers opened windows during teaching time. Achieving a suitable ventilation level could not rely on humans to open windows. Heating, Ventilation, and Air Conditioning (HVAC) systems are not affordable for most NZ schools.