How well can a model capture human thermal sensation? Bridging high-resolution simulations with thermal walks

Abstrakt

Outdoor thermal comfort is one of the key factors affecting human well-being and health in urban environments. Despite threatening billions worldwide, urban heat remains difficult to mitigate effectively. Cities struggle to pinpoint intervention priorities at the pedestrian scale where thermal stress is most acutely experienced. Furthermore, how people perceive and cope with heat extends far beyond thermal exposure; psychological and behavioural responses play a crucial yet often overlooked role. Meanwhile, the variables driving thermal stress remain highly variable at the microscale, falling well below the resolution of conventional monitoring networks and weather-based warning systems. This study presents an integrated approach coupling high-fidelity PALM simulations (1-metre/1-minute resolution) with thermal walks (n = 3,666 georeferenced thermal sensation votes, TSV), applied to Prague-Holešovice (Czech Republic) on a hot summer day. By directly linking human thermal perception with modelling outputs, we assess which variables best explain what people actually experience outdoors and whether a model can reflect human thermal sensation. Our results identify modelled Mean Radiant Temperature (MRT) as the dominant predictor of TSV, exhibiting the highest spatiotemporal variability across the study area, with UTCI showing a similarly significant relationship owing to its strong dependence on MRT. In contrast, air temperature showed minimal spatial variation (≤ 0.3 °C within streets) and substantially lower predictive power, with direct implications for urban warning systems that continue to rely predominantly on air temperature. Distinct spatial patterns were evident at street level. The northern sides of east–west-oriented unshaded streets were systematic thermal hotspots. Mature street trees reduced reported severe thermal discomfort by more than half. Open impervious surfaces amplified heat stress to levels matching the worst street conditions, yet accessible green spaces just tens of metres away offered substantial thermal refuges. The findings highlight radiation exposure as the priority target for urban heat adaptation, with microscale precision as the standard for directing interventions. This approach enables cities to communicate heat risk effectively and act where it matters most.