Application of cool materials on solar protection devices to reduce energy consumption and improve thermal comfort conditions in residential buildings

Cooling down buildings and cities is becoming a priority as a consequence of the global increase of air temperatures. This effect determines the increase of the energy consumption for cooling, as well as the spread of the urban heat island. Cool materials are characterised by high solar reflectance and high solar emissivity. These two properties allow the material staying cool under the solar radiation. Cool materials deserved attention during the few past years and they started being used mainly to protect the building roofs. This paper presents the first results of the potential benefit of cool materials applied on solar protection devices in residential buildings. External shutters are often used, especially in the Mediterranean countries, for security reasons and for solar protection during the hot season. These components are generally characterised by high solar absorbance, due to the typical used colours: brown, deep green, grey. An experimental campaign was carried out to measure the reflectance of conventional coloured materials versus cool coloured ones. A double beam spectrophotometer was used for the testing activity. The results were used as input for typical Italian dwellings, changing some parameters according to: Climatic conditions, insulation level, the presence of a cooling system, orientation, the position of the dwelling respect to the whole building. The cooling energy demand was calculated through a dynamic simulation tool. A first assessment on the impact of the technology in the Italian residential buildings is hence carried out.