Counteracting Urban Thermal Hot Spots in Florence, Italy: The Combined Effects of Vegetation and High-Albedo Surfaces

As cities increasingly face extreme heat, urban planning plays a crucial role in mitigating the urban heat island effect through sustainable cooling strategies. This study investigates the combined potential of vegetation and high-albedo surfaces to reduce urban heat while providing additional ecological benefits in a public square in Florence (Italy). Currently dominated by asphalt, the square represents a summer thermal hot spot, with surface temperatures reaching 50 °C. Using QGIS, ENVI-met, and i-Tree Eco, existing conditions were compared with a redesign scenario including 87 new deciduous broadleaf trees (resulting in a total of 90 trees in the design scenario), 37% permeable green surfaces, 12% semi-permeable parking areas, and 51% high-albedo pavements. Simulations show summer average reductions of about 0.7 °C in air temperature and 6 °C in surface temperature, with maximum reductions of 1.3 °C and ~13 °C on average across the square (up to 20 °C locally under tree canopies and over high-albedo surfaces), reducing “strong” thermal stress areas by 50–60%. Additionally, the new trees provide ecological benefits, including pollutant removal, oxygen production, carbon sequestration, and stormwater interception. This study highlights the importance of predictive microclimatic assessment to optimize urban design and prevent unintended consequences.