Retrofit strategies to mitigate overheating linking urban climate modeling and urban building simulations with outdoor comfort. An urban sector in Malaga (Spain)

Abstract

This work evaluates the cooling effect of retrofit strategies on urban buildings and outdoor comfort in an urban sector in Málaga on one of the hottest days. The methodology links urban climate modeling and urban building simulations with outdoor comfort. The solar reflectance (SR) of roofs, urban surfaces and green areas and their forestation increases after the retrofit. Only the SR façade remains the same, be it in the current or the retrofit scenarios: 0.3. Both façade retrofit strategies consist of an opaque double skin façade (ODSF) with ceramic or metal tiles. Energy cooling is reduced by 52.51% with ceramic and by 52.57% with metal ODSF while urban comfort improves after retrofit: Universal Thermal Comfort Index (UTCI) decreases by 0.62 °C and Mean Radiant Temperature (MRT) decreases by 2.58 °C. Simultaneously, seven points at the pedestrian level assess outdoor comfort in different urban canyons. UTCI decreases more with the metal than with the ODSF ceramic. Regardless the canyon height, the width ratio or the orientation, the UTCI decreases between 2.45 °C and 4.86 °C when under a tree and it decreases more as S/N canyons narrow. This methodology and insights help stakeholders, designers, planners, and policy-makers make data-driven decisions to mitigate overheating and UHI in Mediterranean cities with similar urban building and canyon morphology.