RUOLO DELLE AREE VERDI NELLA MITIGAZIONE DELL'ISOLA DI CALORE URBANA: UNO STUDIO NELLA CITTÀ DI FIRENZE

The Urban heat Island (UHI) it’s a phenomenon that matters several subjects, from phenology to human health. City green areas have an UHI mitigation role that is much more important during summer, when air temperatures in the cities remain high during the evening. The air temperature distribution in the city of Florence was studied in this work according to three different settings: street, garden and courtyard, that is little gardens (less than 500 m2) surrounded by walls. Furthermore, air temperature was analysed according to the distance from the center of the city, the mean number of buildings per km2 and their mean high. As a result of this study, the higher air temperatures were found in the center of the city and just near of it. These zones are even characterized by a smaller quantity of green areas, by a higher urban density and by higher mean high of buildings. Moreover, it is in these areas that the higher air temperature differences between streets and gardens were found. It is important to underline that green areas inside the city behaves, as to air temperature, as rural areas surrounding the city do: in fact, at the beginning of the day (up to 8 am), air temperature keeps high fast in the gardens than in the street, to maintain the same value or nearly lower during the afternoon and to reduce suddenly in the evening, when in the street they keep high for many hours.