Solar reflectance of cool concrete and fiber cement tiles and thermal performance analysis

Refletância solar de telhas de concreto e fibrocimento frias e análise do desempenho térmico

Abstract

Cool tiles are more durable and resistant roofing materials and have high solar reflectance, therefore, their surfaces have lower temperatures compared to conventional tiles. Thus, the objective was to evaluate the reflective behavior and thermal performance of cool tiles that are available in the Brazilian market considering that these data are not available. To achieve that, the color parameters and the spectral reflectance of seven cool concrete and fiber cement tiles were measured and their surface temperatures were monitored during the period of greatest sun exposure on a hot and dry day in the city of São Carlos, in the state of São Paulo. The cool tiles of darker colors, despite the reflective coating, are the most heated even compared to conventional finishing tiles. White tiles have better reflective performance and have presented the lowest surface temperatures because of the higher reflectances in the visible region due to their coloration. Despite this, the near infrared is the spectral region with the highest predicted surface temperature reduction, which was confirmed in the Pearson correlation analyzes that were performed with the thermal camera and the infrared thermometer used in the surface temperature measurement.

Keywords
Cool tiles; Solar reflectance; Surface temperature; Thermal performance