Designing climate-resilient urban environments : an empirical assessment of urban morphology and street trees on microclimatic regulation in Dresden, Germany

Abstract

Urban heat risk is increasingly recognised as a critical challenge in the context of climate change, particularly in densely built environments where the Urban Heat Island (UHI) effect amplifies thermal stress and impairs outdoor thermal comfort. This study examines how urban morphology and vegetation characteristics - particularly tree maturity - influence microclimatic conditions at the parcel scale and explores the potential for climate-positive densification in Dresden, Germany. A mixed-method approach combining in-situ field measurements and three-dimensional ENVI-met simulations was employed to quantify spatial variations in air and surface temperatures, as well as relative humidity, across a representative range of land cover typologies. To further evaluate potential mitigation strategies, an intervention scenario was simulated involving the introduction of mid-rise buildings alongside a structured increase in tree canopy cover. The results reveal that mature trees substantially mitigate heat exposure, with surface temperature reductions exceeding 15°C between sealed and vegetated zones, thus highlighting the critical role of urban green infrastructure in regulating surface energy balances. Moreover, the integration of compact urban form with targeted greening demonstrated a capacity to improve diurnal thermal conditions while avoiding significant increases in nocturnal heat storage - a frequent drawback of conventional densification models. These findings emphasise the significance of synergistic urban planning approaches that balance morphological efficiency with ecological functionality. Nonetheless, the study is limited by its reliance on a single-day observation during peak summer and the temporal constraints of the modelled scenarios, suggesting the need for longitudinal and seasonal analyses to capture a broader range of climatic variability and ensure the robustness of climate-adaptive design strategies.