The use of cool materials for heat island mitigation has gained a lot of interest during the past few years. Cool materials are characterized by high solar reflectance and infrared emittance values. To maximize cooling energy savings, high albedo roof coatings should maintain the above properties for the service life of the coating. The aim of the present paper is to analyze the weatherisation of the cool roofs in two buildings in Athens Greece. The optical properties of the aged and new cool roofs are measured and compared. The impact of ageing in the two buildings' energy performance is estimated. A mineralogical analysis is performed in order to quantify the deposition of pollutants on the cool roofs' surface. In addition, a series of microbiological tests are implemented to reveal the impact of ageing and weatherisation in health. In both school roofs the surface temperature has a significant decrease between the part of the existing cool coating and the application of the new part with a temperature difference reached reaching 7-12 K. (C) 2015 Elsevier B.V. All rights reserved.