Exploring the potentialities of cool facades to improve the thermal response of Mediterranean residential buildings

Cool materials are characterized by high solar reflectance and by high thermal emissivity, the combination of these two radiative properties allows such construction materials to remain cooler than conventional materials of the same colour under the solar radiation. During the past decades there was a growing interest mainly for roofing and pavements applications, aiming at cooling buildings and cities. This study presents the potentiality of the technology for façade applications in residential buildings, focusing on the performance in the Mediterranean region, where cooling energy uses and urban heat islands are critical issues. The study analyses the performance of cooled and non-cooled buildings by means of dynamic simulations, showing the potentiality of the technology in terms of energy performance and impact on indoor thermal comfort. Calculations are carried out for several building configurations and climatic conditions; also the impact of different solar reflectance values of facades, depending on their orientation, was explored. Cooling energy savings up to 2.9 kW h/m2 per 0.1 increase of solar reflectance are calculated. The average indoor operative temperature is reduced up to 1.1 °C in non-cooled buildings during the summer period. Average exterior surface temperature reductions up to 7.5 °C, with peak reductions up to 25 °C, are calculated.