Comparative Modeling of Greening Design Scenarios for Sustainable and Climate-Responsive Urban Regeneration: Microclimate and Thermal Comfort Effects in an Italian Case Study

Urban overheating poses major challenges in Mediterranean cities, affecting public health and well-being. This study comparatively evaluates how alternative greening configurations influence urban microclimate and outdoor thermal comfort in a brownfield regeneration site in Imola, Italy, using ENVI-met simulations under a representative extreme summer condition. Eight scenarios with varying vegetation density, structure, and spatial arrangement were modelled on the hottest day of the year, and the Physiological Equivalent Temperature (PET) was evaluated at representative times. Results show that greening reduces heat stress, though its effectiveness varies over time and across configurations. No meaningful cooling occurred at 5:00 a.m., confirming that vegetation has a limited impact during nocturnal radiative processes. At 9:00 a.m., the medium-density scenario (S2b) achieved the greatest PET reduction (~2 °C), suggesting favorable evapotranspiration conditions under moderate radiation. At 4:00 p.m., the distributed high-density scenario (S3.2b) provided the strongest mitigation (~1.8–2 °C). Distributed layouts outperformed clustered ones, highlighting the non-linear nature of vegetation cooling. Zonal analysis showed the largest cooling in public green areas, followed by parking, building, and path zones, demonstrating the influence of surface type and shading geometry. Greening also produced modest improvements in surrounding neighborhoods (up to 0.8 °C in the morning), although impacts remained localized. Overall, results highlight how vegetation quantity, structure, and spatial distribution influence cooling performance under critical summer conditions, supporting climate-responsive urban regeneration design. These findings contribute to sustainable urban planning by supporting nature-based strategies for climate adaptation and improved environmental quality in regenerating urban districts. Future work should consider seasonal vegetation dynamics and multi-objective design optimization.