A study of indoor environment and window use in French dwellings monitored during a summer with heatwaves

Heatwaves are extreme events that will become more frequent and intense with climate change. Maintaining a comfortable and healthy indoor environment becomes crucial during these periods. The occupants are not just passive individuals who undergo the evolution of their environment. They can act to ensure their thermal comfort, in particular by opening or closing windows in summer.
This article thus aims to examine the thermal environment and indoor air quality during the summer period in French dwellings. Window use is studied in order to identify the physical and contextual factors influencing the occupants’ behaviour thanks to a feature selection algorithm.
Four dwellings, three in a multi-family building and one in a single-family house, were monitored between June and September 2022. Three heatwaves occurred during this summer in the French region Auvergne-Rhône-Alpes. In addition to measurements of the indoor and outdoor environments, occupant actions on windows, fans and air conditioners were recorded. Three types of surveys were conducted with the occupants to understand their perceptions, experiences, and overall use of the dwellings.
The results show that the four households have different window use behaviours. Analysis of the data revealed that the variables influencing occupants’ window behaviour are indoor and outdoor air temperatures, indoor CO2 and light VOC concentrations, global horizontal irradiation and time of day.