An investigation of the influencing factors for occupants' operation of windows in apartments equipped with portable air purifiers

Abstract

As operations of windows by occupants can greatly affect building energy consumption and indoor air quality, understanding the driving factors of this adaptive control behaviour is of great importance. The present paper reports on an investigation into the influencing factors for window operation behaviour in eighteen newly-built, low-energy apartments in London, UK. A range of indoor and outdoor environmental variables (including temperature, relative humidity, CO2 and particulate matter) as well as the window status (open/closed) were monitored for 6–11 months. About half of the apartments included monitoring for nearly three months during a national pandemic lockdown. Additionally, each apartment was provided with a portable home air purifier (HAP) to use during most of the study period. The effects of environmental variables and the use of HAPs on occupants' operations of windows in the main bedroom were analysed according to different periods (free-running, heating and lockdown period) and occupancy stages (arrival, departure and intermediate occupied times). Results indicated that analysing the heating period alone could lead to explanations of window operation behaviour that were contradictory to those from analysing other periods, and separating the dataset based on different occupancy stages to develop behaviour models was of little value. The results of statistical significance tests showed that indoor temperature was the leading driving factor for occupants’ window opening and closing behaviour, whereas neither air quality-related variables nor the use of air purifiers had a statistically significant impact on window operation behaviour.