Colored Cool Materials

This chapter provides a discussion on colored cool materials. The relationship between the solar spectral irradiance and the solar spectrum reflectance for colored cool paints is important for the performance of these paints. The majority of the Japanese paint market is occupied by dark colored paints, which have an average solar reflectance of around 20%. Paints with a solar reflectance of more than 20% probably contribute to the urban heat island effect. However, reduction of solar reflectance by adhesion of atmospheric particles is found to occur immediately after application of the paints, and the solar reflectance of some colored cool paints is found to reduce to 60% of the initial value within one year. The roofs of most detached houses in Japan are covered with tiles; it is therefore important to examine the effect of tiles on the urban heat island measures. The average solar reflectance of areas of detached housing is estimated to be around 16%. Roof materials with a solar reflectance of more than 20% probably contribute to urban heat islands. Solar reflectance of an uneven tiled surface can be estimated from the surface shape and the solar reflectance of a flat surface.

Keywords: Colored cool materials, spectrum solar reflectance, luminosity and solar reflectance, revelation, japanese roof tiles, surface shape, market in Japan.