Impact of Cool Materials on Ambient Temperatures in an Urban Area

The urban heat island is a problem that affects our cities and results in a warmer climate in the urban and residential areas compared to the surrounding rural areas. One solution to this problem involves the use of materials with high solar reflectance and high thermal emissivity, the so-called “Cool Materials”. Their surface temperatures are much lower than those of typical building materials. Usually Cool Materials are used to decrease heat flow entering in a building, but if used on an urban scale, their lower surface temperature lead to a lower heat exchange between air and surfaces, helping to decrease the air temperature of the urban environment. The paper reports the results of a study carried out on a densely populated area in Rome of about 500.000 m2. The study was divided into three parts. The first part involves the comparison and the analysis of data collected by weather stations of airports and public agencies located both in urban areas and in peripheral areas in order to monitor the magnitude of the heat island effect. The second part includes measurements of the thermal properties of some Cool asphalts. The third part is focused on numerical analysis of the phenomenon through the creation of a model included in a S.V.A.T. software that allows to compare the outdoor air temperature of an area before and after a hypothetical use of Cool Materials on external surfaces of buildings and street pavements. The results of this study demonstrated the significant influence of cool materials on the reduction of the heat island phenomenon