mitigation 4.1.1. Roof surface temperatures The temperature reached on the building surfaces strongly influences the air temperature in the urban environment. Hence, the calculation of the roof temperature is a basic step to study the effects of the proposed solutions in terms of Urban Heat Island mitigation.In particular, Fig. 2 shows – for each roof technology the hourly profile of the roof outer surface temperature resulting from the simulations in three particularly hot days in summer, namely from the 8th to the 10th of August in Catania, from the 14th to the 16th of August in Rome and from the 30th of July to the 1st of August in Milan. The curve of the solar irradiance on the horizontal plane is also reported.