Activity hours: Assessing liveability during heatwaves

As climate change increases the frequency and severity of heatwaves, understanding their impact on the well-being, health, and permissible activities of building occupants becomes crucial. Existing work focuses primarily on the thermal comfort of an average individual, neglecting both the impact of extreme heat on liveability and variability in resilience of different population groups. To address these gaps, we introduce the Activity hours (Ah) metric, which quantifies the liveability of indoor environments during heatwaves while taking into account air temperature, humidity, occupant age, permissible activity levels, and duration of exposure. We also present the Heatalyzer tool that allows the computation of Ah for different geographies, building archetypes, and heatwave durations. Through a case study of residential housing in London, we compare Ah with established thermal comfort metrics, highlighting Ah's ability to quantify heatwave impacts on occupant liveability for different building types and demographic groups. Our results are made widely accessible through the Heatalyzer dashboard, an intuitive website that enables London residents to evaluate their exposure to heat-related risks.