Thermal comfort on the move: Understanding thermal alliesthesia on urban walking routes

Walking outdoors exposes pedestrians in urban settings to diverse and complex sequences of microclimates which can potentially prompt experiences of thermal alliesthesia: transient feelings of thermal pleasure (positive alliesthesia) or discomfort (negative alliesthesia). While adventitious spatial microclimatic variations hold potential to enhance pedestrian thermal comfort, their practical application in urban design contexts remains underexplored in the literature to date. This study investigates how thermal alliesthesia can be leveraged to enhance the subjective thermal experiences of urban pedestrians. To address this question, 51 human subjects were recruited to walk along a designated outdoor route in Beijing, specifically selected to present thermal transitions that could potentially stimulate thermal alliesthesia during winter, spring and summer. As the residual heat accumulating in or depleting from body tissue when its heat inputs and outputs are unbalanced, thermal storage (TS) is utilized to characterize the objective thermal status within the human body and quantify the boundaries of the thermoneutral zone. Results identified a moderate thermal alliesthesia potential zone within the range of 8.05–93.23 W/m² thermal storage. Within this zone, the variations of TS and thermal comfort vote (TCV) follow a quadratic relationship, while in strong thermal alliesthesia potential zones, they follow a linear relationship. Both temporal and spatial variations in thermal conditions influence TCV. This study demonstrates how spatial microclimatic variations can be curated to enrich the subjective experience of pedestrians in urban settings, providing a framework for purposively applying thermal alliesthesia principles in urban design and pedestrian environments.