Experimental and numerical evaluations on the energy penalty of reflective roofs during the heating season for Mediterranean climate

During the cooling season, the beneficial effects of cool colors and cool paints are multiple and undebatable. Really, it is not well-know their impact during the heating season, when a heated external surface could be useful in order to reduce the heat losses. This paper, by means of experiments and numerical simulations, investigates the effect of high-reflective and high-emissive coatings on the building energy performance in Mediterranean climate. Four coatings are used; among these, an acrylic white paint of household appliances or automotive sector has been tested since it is characterized by very fast drying, good adhesion directly to different type of materials, greater durability than traditional paints and lower costs. The experiments have been carried out by using the test-room of the University of Sannio; the results of wintertime monitoring campaign are presented. By means of simulations, using as case study a typical office building, the effect of combination of roof reflectivity, roof technology and insulation thickness is discussed. Research results can support design strategies for optimizing the yearly energy performance of the building, reducing environmental impacts but these also demonstrate the performance of unconventional cool material, as the acrylic paint, with a lower aging and maintenance needs.