Mitigation strategies of the urban heat island intensity in Mediterranean climates: simulation studies in Rome (Italy) and Valparaiso (Chile)

The Urbanocene, a proposed new geological epoch characterized by the urban living condition, is pressing the humanity to respond shortly to important challenges. Cities are at the same time the places where we live in and the big dissipators of the final energy to the environment. The simultaneous rules of heat dissipator and place to live are quite contradictory, because of the increasing temperatures of the dissipator surfaces, phenomenon known as Urban Heat Island (UHI). Mediterranean climates should suffer, in the next years, changes in the thermal needs of buildings and in the outdoor comfort sensations. A change in the energy demand from heating to cooling is probable and overheating reduction could be a priority in the future. Many mitigation strategies of UHI are being discussed in these years, such as the city greening, the use of cool materials for roofs and soils, the reduction of automobile dependence, the shift to new urban morphologies. In this paper an evaluation of impacts of different possible strategies is done, by using computational simulations for various sectors of Rome and Valparaiso. Results show the importance of greening and traffic reduction to achieve better comfort; while to reduce building energy consumption changes in urban morphology and traffic are suggested as the best strategies.