Variations in classroom ventilation during the COVID-19 pandemic: Insights from monitoring 36 naturally ventilated classrooms in the UK during 2021. (1st January 2023) - Burridge, Henry C.
Abstract: Seasonal changes in the measured CO 2 levels at four schools are herein presented through a set of indoor air quality metrics that were gathered during the height of the COVID-19 pandemic in the UK. Data from non-intrusive environmental monitoring units were remotely collected throughout 2021 from 36 naturally ventilated classrooms at two primary schools and two secondary schools in England. Measurements were analysed to assess the indoor CO 2 concentration and temperature . Relative to UK school air quality guidance, the CO 2 levels within classrooms remained relatively low during periods of warmer weather, with elevated CO 2 levels being evident during the colder seasons, indicating lower levels of per person ventilation during these colder periods. However, CO 2 data from the cold period during the latter part of 2021, imply that the per person classroom ventilation levels were significantly lower than those achieved during a similarly cold weather period during the early part of the year. Given that the classroom architecture and usage remained unchanged, this finding suggests that changes in the ventilation behaviours within the classrooms may have altered, and raises questions as to what may have given rise to such change, in a year when, messaging and public concerns regarding COVID-19 varied within the UK. Significant variations were observed when contrasting data, both between schools, and between classrooms within the same school building; suggesting that work is required to understand and catalogue the existing ventilation provisions and architecture within UK classrooms, and that more work is required to ascertain the effects of classroom ventilation behaviours. Highlights: Environmental condition data in classrooms throughout the pandemic year of 2021 presented. CO 2 data indicate seasonal variations in per person classroom ventilation rates. Significantly lower per person ventilation rates towards the end of 2021. Inter-school differences underscore need to openly catalogue school estate facilities. Significant intra-school difference suggest classroom ventilation behaviours may be important.