Microclimate monitoring and modelling in a regenerating urban environment: Milano (Italy)

Urban regeneration projects in densely populated areas often involve limited, small-scale interventions. The present study provides a data-driven evaluation of solutions to mitigate the urban heat island effect at microscale, integrating densely distributed multisensory and multitemporal monitoring, material characterization, and microscale modelling. A dedicated monitoring system was utilized to measure microclimatic variables during the various phases of regeneration of a compact public square in Milan (Italy). The observations were utilized to establish boundary conditions and to calibrate and validate a microclimatic numerical model for a typical summer day. Three configurations representing different stages of regeneration were analyzed: pre-regeneration conditions, post-regeneration, and a future planned condition. The results obtained from the study indicate that changes in near ground air temperature were limited, whereas surface temperatures and radiative conditions exhibited clearer contrasts linked to the optical and thermal properties of materials and to shading. Reflective paving reduced surface heating in some locations but did not improve mean radiant temperature under peak solar exposure, with local increases that may penalize pedestrian comfort. The findings of this study suggest that the most significant reductions in radiative heat load and the most marked improvements in thermal comfort are produced by mature tree shading. This highlights the importance of optimizing shade placement relative to pedestrian-use areas and of considering soil moisture and maintenance. The objective is to provide support in optimizing mitigation strategies in regeneration projects, highlighting positive aspects and critical points in the distribution of solutions designed to benefit both the microclimate and pedestrian comfort.