Thermal Impacts of Stationary Vehicles on Urban Microclimates: Insights from Field Measurements and Exploratory 3D Modelling

Urban microclimates are traditionally interpreted and modelled based on permanent built surfaces, while semi-permanent elements such as stationary vehicles remain largely overlooked in urban climate studies. Despite their distinct radiative and thermal behaviour and increasing spatial prevalence in contemporary cities, parked vehicles are rarely represented in urban microclimate modelling frameworks. This study provides an exploratory assessment of a commonly used three-dimensional modelling workflow to approximate near-vehicle air temperature patterns at the micro-scale by comparing simulated results with field measurements collected in Lisbon, Portugal. Air temperature was measured in an open parking environment with unobstructed sky exposure, at multiple heights above two black and two white parked vehicles during summer, and corresponding simulated values were extracted at matching locations. Simulated mean air temperatures showed reasonable agreement with observations (MAE = 0.6–0.9 °C; RMSE = 0.7–1.3 °C), suggesting that simplified modelling approaches can reproduce general air temperature patterns under controlled conditions. However, larger localised deviations were observed near vehicle surfaces and rear positions, particularly for dark-coloured vehicles, highlighting limitations in resolving fine-scale radiative and aerodynamic processes. The findings indicate that stationary vehicles can be represented as distinct urban surfaces, while emphasising the need for improved parameterisation to enable their integration into urban microclimate models at larger spatial scales.