Reducing UHI in historical centres: the greening transformation of open small spaces in San Lorenzo district in the city of Naples (Italy)

Urban Heat Island effects intensify thermal discomfort and energy consumption in densely built areas, particularly in historical city centres characterised by compact and stratified urban fabric. Such conditions necessitate targeted greening interventions in these urban fabrics, which are the focus of this study on the San Lorenzo district in Naples, a representative Mediterranean historic city, where limited open spaces coexist with strict heritage conservation constraints. Utilising ENVI-met 5.7 simulations, the research models microclimatic conditions under current and greening scenarios, considering detailed urban morphology, vegetation types, and local climate data representative of peak summer days. Physiological Equivalent Temperature, Mean Radiant Temperature and Universal Thermal Comfort indices are employed to measure thermal comfort improvements through targeted greening interventions in small yet strategically significant spaces like inner cohorts of historical buildings. The findings demonstrate the cooling potential of integrating green transformation also in the small inner courtyards of the noble buildings by restoring the original function of these spaces as gardens and orange groves. This kind of solution can be efficiently adopted for a sustainable urban planning, helping mitigate UHI impacts and improve residents’ well-being amidst global warming challenges.