A composite cool colored tile for sloped roofs with high ‘equivalent’ solar reflectance

Abstract

Mediterranean cities are characterized by sloped roofs with ceramic tiles of traditional colors such as brick red in different tones. Their solar reflectance is generally low and can cause overheating of the building due to solar gains during the hot season.In this work, an innovative approach is tested to achieve roof tiles with high capacity of rejecting solar radiation. It consists of using a cool-colored tile with relatively high solar reflectance, combined with a thin insulating layer attached below the tile and made of a silica-gel super-insulating material. An aluminum foil with very low thermal emittance is also applied below the insulating layer. Along the perimeter of each tile, line brushes are attached in order to enclose an almost sealed air space between the aluminum foil and the roof slab below when the tiles are supported on wooden battens.Composite tiles like that outlined here can provide a strong increase of roof thermal resistance, helpful to control either heat loss in winter, or building overheating in summer. They can be installed onto an existing roof, for instance the sloped tile roof of a historical or traditional building, with no need to modify the roof height and structure.