Comparative analysis between portable spectrometer and integrating sphere spectrophotometer for measuring solar reflectance of tiles

Abstract

Knowing the thermal properties of the surfaces of building envelope, such as the solar reflectance, is essential for the use of passive strategies to improve thermal performance of buildings. However, there is a lack of data for coatings produced in Brazil, because of the low availability of equipment and the need of specialized technicians. In order to simplify the access to these data, this work proposes the portable spectrometer ALTA II as an alternative to standardized measurement methods for solar reflectance of ceramic and fiber cement tiles. Therefore, solar reflectance data measured with a spectrophotometer with an integrating sphere were compared with those measured with the ALTA II for 39 tiles. Performance analyses of ALTA II from variations in the measurement method (with and without dark apparatus indoors and without apparatus outdoors) were inconclusive in determining the influence of the absence of a dark apparatus for the measurement on the selected samples. Despite the observed uncertainty, the research results showed strong correlation between the data measured on the ALTA II with the apparatus and with the spectrophotometer, indicating the spectrometer as an alternative for the solar reflectance measurement of these samples.