A aplicação dos materiais frios na envoltória é uma técnica passiva que pode contribuir na eficiência energética de edificações. A fim de avaliar o desempenho térmico de tintas frias nacionais, mediu-se a refletância solar em laboratório e a temperatura superficial de amostras expostas ao Sol. Os resultados indicaram diferenças significativas de refletância para tintas de mesma cor, porém com menor variação de temperatura entre elas. Contudo, a reflexão no infravermelho próximo mostrou-se mais relevante para reduzir a absorção de calor nas superfícies, comprovando-se a importância da obtenção de dados medidos em laboratório para a escolha adequada de revestimentos para edifícios.

One way to contribute with reduction of greenhouse gas emissions and air pollution is decreasing energy consumption for cooling purposes in buildings, among solutions, using cool materials as coatings in buildings. Cool material has high reflectance of specular and diffuse components of solar radiation and its surface heats up less than a conventional one with same topcoat. Thus, research's aim was to evaluate optical, thermal and chemical properties of cool coatings available in Brazil and their relationship with thermal performance for buildings' envelope. Thus, coatings were chosen for use on walls and roofs buildings' which have "thermal" or "reflective" denomination from products available on national market. In this way, tiles, paints and reflective powder additive (to be added to conventional paints) for roofs and facades were evaluated. Measurements were performed of CIELab color coordinates, solar reflectance and thermal emittance were performed using standardized methods and equipment for 34 cool materials and 07 reference materials. Thermal images of samples exposed to the Sun were recorded in the city of Sao Carlos (SP) and, in addition, chemical analysis quantified chemical elements present on samples' surface. Results showed that: a) visible spectral region contributed with the greatest temperature reduction by multiple regression analysis. Therefore, lighter-colored surfaces heat up less, into a greater level, because of their greater visible reflectance and had the lowest surface temperatures; b) dark reflective materials, despite greater reflectance in the near infrared than visible, did not obtain lower surface temperatures in relation to the conventional ones; c) all evaluated materials presented high thermal emittance with insignificant variations concerning conventional ones and d) correlation analyzes indicated that higher concentration of metallic element titanium decreases thermal emittance, however, no statistical significance was found between greater amounts of titanium or silicon, from inorganic oxides, with increased near-infrared or solar reflectance. This research aimed for identify which chemical components present on cool materials surface interfere with solar reflectance and thermal emittance highest values and therefore contribute with information to assist in most appropriate choice of reflective coatings for building envelope.