Thermal performance of coupled cool roof and cool façade: Experimental monitoring and analytical optimization procedure

While UHI mitigation potential of cool roofs has been deeply investigated compared to cool façades, still not sufficient research effort has been dedicated to quantify the benefits of combined cool building products. The present work evaluates the thermal performance of an innovative cool roofing membrane and a cool façade painting applied on a prototype building. Moreover, an analytical procedure able to predict the cool coating thermal performance is elaborated. Such methodology can be used to determine the passive cooling potential of each product as a separate envelope component and as a combination. To this twofold aim, a preliminary in-field monitoring is developed. Therefore, a sensitivity analysis is performed to evaluate the separate and combined passive cooling contributions of the roof and the differently oriented façades. Finally, the analytical procedure is developed to define external surface temperature profiles able to predict the building coating thermal performance by minimizing the number of temperature measurements. Results show the major contribution of cool roof membrane in reducing indoor operative temperature. Nevertheless, a non-negligible cooling effect in terms of outdoor surface temperature is imputable to the South cool façade. Moreover, the analytical model shows an acceptable accuracy in representing the behavior of the building coating.