Numerical Experimentation to Study the Influence of Various Urban Features on Microclimate Using Different Urban Scenarios

Rapid urbanization, compounded by climate change, exacerbates temperatures in urban regions by intensifying the urban heat island (UHI) effect. This study explores the influence of urbanization patterns on urban microclimate in Turin, Italy, through numerical simulations. Various urban design scenarios were investigated using weather research and forecast models integrated with a multilayer urban canopy model (MLUCM) over the June 2019 heatwave period. High-resolution urban land use/land cover data derived from local climate zone (LCZ) maps generated through the World Urban Database and Access Portal Tools (WUDAPT) were utilized. Results indicate a significant impact of urbanization on UHI, demonstrating an average nighttime temperature reduction of 2.4°C and daytime temperature reduction of 1.6°C in urban areas when urban built-ups are replaced with vegetation. Replacement of compact-rise buildings alone notably impacts local climatic conditions, decreasing average temperatures by 1.75°C in the city center, with an overall urban temperature decrease of 0.9°C. Conversely, the substitution of industrial zones yields a 1.4°C average urban temperature decrease, with minimal impact in city centers (0.14°C reduction). Substituting compact-rise buildings with open-rise buildings slightly reduces urban nighttime temperatures and significantly reduces the critical velocity required to mitigate UHI. Furthermore, the adoption of open-rise buildings fosters enhanced wind flow in downstream rural areas, potentially contributing to a reduction in urban temperatures on windy days by facilitating ventilation and other cooling processes. This research emphasizes the critical role of specific urban features in mitigating UHI and improving thermal comfort. By strategically incorporating green spaces, open-rise buildings, and wind-channeling designs, urban planners can create more resilient and thermally comfortable cities.