REFLETÂNCIA SOLAR E O DESEMPENHO TÉRMICO DE TELHAS EXPOSTAS AO TEMPO

Abstract

A simple and effective solution to reduce the effects caused by the increase of surface and air temperatures in the built environment, and consequently to improve the conditions of thermal comfort of people, is the use of external coatings with high solar reflectance combined with high thermal emittance. If used in roofs, this type of material can contribute to minimize the undesired heat gains into buildings in a more relevant way than in vertical surfaces, since the incidence of solar radiation on the roofs is much more intense than on the other faces of the constructive envelope. Changes in the solar reflectance of coatings have already been identified because of the exposure over time to weathering conditions, which impacts on the thermal performance of it. In this sense, this work in progress aims to analyze the aging of 31 tiles of 4 different groups (ceramic, glazed ceramic, concrete, and metal) and their direct impacts on the thermal gains of buildings through changes in the values of solar reflectance of the samples analyzed after exposure to weathering conditions. The tile’s thermal performance will be evaluated from spectrophotometer reflectance measurements every 3 months and the continuous monitoring of surface temperatures of the exposed tiles over 12 months. Up to the present moment, reflectance measurements for new tiles were carried out, without aging, and the results indicated that ceramic tiles have higher solar reflectance to the other types, with a mean difference in reflectance of about 40% higher than concrete tiles, for example.