Thermal impact of a redeveloped area on localized urban microclimate: A case study in Rome

Abstract The increase in urbanization leads to an intensification of the heat island effect, due to several factors: reduction in green areas; high solar absorptance of construction materials; waterproof surfaces; low sky view factors and natural ventilation effectiveness. Urban heat island characteristics have vast impacts and implications on energy efficiency, environment, and at last on human comfort and health. The development of urban fabric involves the modification of the thermal fluid-dynamic field of the whole area around the new buildings. This factor leads to worse the energy performances of all the structures affected by the phenomenon. The study investigates on the impact of a new building complex as result of a redevelopment process on the thermal and energy performances of the actual surrounding urbanized area sited in Rome. The purpose is to provide results to better understand the urban heat island effects on climate inside cities and population health. The assessment was carried out through a monitoring campaign and numerical analyses. The temperature field and the Universal Thermal Climate Index (UTCI) were calculated for the current scenario of the area, for the redeveloped configuration and for a proposed scenario characterized by the adoption of mitigation strategies against urban heat island countermeasures, such as vegetation improvement and cool materials able to limit the surface temperature rise under solar radiation. The new redeveloped configuration of the area induces an increase in average air temperature up to 3.5 °C in the central part of the day and a worsening of the maximum UTCI index up to 2.7 °C. This is caused by the increase of the number of obstacle to the natural ventilation, the replacement of soil and spontaneous vegetation with low albedo materials. The application of cool materials and vegetation determines a temperature decrease up to 2 °C, while the maximum UTCI reduction is moderate, about 1 °C.

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