Urban and building scale strategies to cool cities: the case of a coastal city in the Mediterranean climate

The scope of this investigation is to evaluate the effects of cooling mitigation strategies on the outdoor microclimate of a neighborhood located in Naples (Italy). It is a historical district that runs along the Neapolitan waterfront and is affected by a summer overheating phenomenon, confirmed by registered temperatures higher than 35°C. The paper evaluates the cooling effect of cooling passive strategies on the outdoor microclimate, but also their efficacy in improving building energy performances and indoor comfort, focusing both on the urban and building scale. The urban scale evaluation was performed through a simulation model, whose reliability was verified by spot on-site measurements performed during a typical warm day in the summer. High solar reflectance materials for roofs, green roofs and green facades, and urban vegetation at ground level were singularly analyzed. Except for the urban vegetation, the proposed passive strategies were evaluated through BES, on two representative building typologies in the district, to analyze their effect on the buildings cooling and heating needs and on indoor thermal comfort. The results show, on an urban level, the cooling role of green lung skirting the Neapolitan seafront, and the efficacy of the mitigation strategies in reducing the peaks of air temperatures and improving air quality without compromising the historical value of the district. On the building level, the efficacy of the passive measures in reducing the cooling energy needs and improving indoor comfort is demonstrated, with a maximum reduction of the cooling need of 21% through the addition of cool roofs.