Thermal performance of different glazing surfaces in a hot climate

This paper describes an experimental study about thermal performance of different glazing materials in prototypes. In Brazil, due to its low latitudes and predominantly hot and humid climate, high solar radiation provokes strong heat gain in almost all the regions of the country. The worst building exposure conditions are on north and west facades. In previous work, the transmissivity to solar radiation for the more frequently used window glasses in buildings in Brazil was obtained through spectrophotometric analyses. The aim of this work is to study the behaviour of transparent materials regarding solar heat gain, through measurements in prototypes. Thermal properties of different float and reflective glass samples were analyzed, through data collection of ambient and surfaces temperatures. Glazing facade was west-oriented. There was no ventilation indoor. Results show that in all cases, during daytime, the internal air temperatures stay below external air temperature. A difference of up to 3oC in the indoor air temperatures of prototypes was observed. Thermalabsorbent glasses present high surface temperatures, due to absorption of solar radiation, but in spite of that, they show a significant decrease in indoor air temperature.