solar reflectance

Solar reflectance is the key performance parameter of cool roof and cool pavement materials. For its assessment, the measured spectral reflectivity of the sample is weighted by a reference spectrum of solar irradiance. Several standard and non-standard spectra are however available, taking into account different climate conditions, angle of incidence of the solar beam, contribution of the diffuse radiation content.  

The present study aims at investigating different methodologies and standards for measuring and calculating solar reflectance and infrared emittance, the two main properties characterizing cool roofing materials. In order to achieve this goal, an interlaboratory comparison testing has been set up among several laboratories that are members of the European Cool Roofs Council.

Energy saving in the building sector is one of the key issue to achieve environmental targets at national and EU levels. Even if characterised by a large number of different climatic conditions, Italy energy policies were aimed at reducing the energy consumption related to space heating in buildings, neglecting other relevant energy uses as space cooling, which has dramatically increased in the past years. The recent EU Directive for the State Members is to assess the energy quality of buildings taking into account all the relevant energy uses. 

This paper aims to report the solar and thermal data for various common and innovative materialsused in outdoor urban applications. The tested materials include various types of coatings, tiles andasphalt pavement. In the framework of this research, the spectral reflectance and the emissivity of thematerials were measured using a UV/VIS/NIR spectrophotometer fitted with an integrating sphere andan emissometer. The solar reflectance of the samples was calculated.