Microclimate Mitigation for Reducing Summer Overheating in Historic Districts
Abstract
In the context of dense cities, which typically suffer from the Urban Heat Island (UHI) phenomenon, environmental quality is strongly affected by urban design choices and can significantly vary depending on the local boundary conditions and local climate phenomena. In this scenario, the present work analyzes the complex relation between the urban built environment and its local microclimate at neighborhood-urban scale, by means of both experimental field monitoring and numerical analysis. To this aim, an historic urban district in the city center of Perugia (central Italy) was continuously monitored during summer 2015 and the UHI intensity was assessed. Therefore, the validated numerical analysis of the area was carried out through ENVI-met simulation engine in order to quantify the thermal benefits achievable by applying specific tailored mitigations strategies, i.e. green façade, cool roof, and cool pavement, in both summer and winter conditions. The monitoring campaign confirmed that buildings’ density and greenery percentage are able to considerably affect outdoor microclimate even in historical districts where the design choices are relatively limited compared to the new urban developments. The numerical analysis highlighted the major role of green façade in generating the most important air temperature drops in a summer day. Moreover, the effectiveness of the proposed mitigation technique is demonstrated also in winter conditions.
Keywords
Outdoor microclimate, Urban heat island, Experimental monitoring, Numerical analysis, Local boundary conditions