Urban Green Spaces and Their Role in Responding to the Heat Island Effect in Historical Urban Context

Urban vegetation is a proven and natural solution for cooling cities and providing comfort, clean air, and social, health, and economic benefits. Among many ecosystem services (ES), urban vegetation plays a major role in protecting biodiver- sity and providing passive thermal comfort conditions. Urban parameters, such as urban typology, building materials, and density interact with urban vegetation, which influences the microclimate of the built urban environment. The multiple services offered by urban vegetation are lessened because of the urban heat island (UHI), an extensive phenomenon caused by urbanization, which leads to higher air tempera- tures in urban centers. This occurs because of the prevalence of low-albedo surfaces, construction materials with high thermal capacity, and a lack of transpiring vege- tation, which results in greater absorption of solar radiation. Heat accumulates and causes an increase in air temperature. While dense and large urban green areas have several effects on their surroundings, the extent to which vegetation lowers local temperatures has not been quantified yet, especially in future weather. This paper presents a microclimatic evaluation of two green areas in the city centers of two dense and compact cities in Italy. The evaluation will compare the current situation with a projected future scenario (2050). Air temperature, wind speed, mean radiant temperature (MRT), and the physiologically equivalent temperature (PET) are simulated using ENVI-met to investigate the current and future role of urban green spaces in mitigating the urban heat island effect.