An experimental study of the effects of using cool materials at different building heights on the indoor and outdoor environment

Four building arrays, each comprising 25 building models, were utilized to investigate the effects of cool materials on building surface temperatures, indoor temperatures, and street microclimates in Guangzhou, China. The experiments are divided into three groups. The first group of the experimental models is used to investigate the cooling effect of the roof using cool materials on the roof surface and indoor environment. The results show that using cool materials on roofs can significantly reduce roof surface and indoor temperatures of the top floor by 13.5°C and 3.9°C at noon under an average global solar radiation (GSR) of 727 W/m2. The second group of experiments included these four arrays: one control group without cool materials and three other arrays applying cool materials on the third, second, and first floors, respectively. Using cool materials on the façades of the third, second, and first floors reduced the indoor temperature by an average of 1.9°C, 0.8°C, and 0.5°C (average GSR=404 W/m2), respectively. As a result, higher floors receive more solar radiation, and cool materials show better cooling capacity. The third group is used to investigate the effect on street air temperatures when cool materials are used on all building façades. Overall, the effect of cool materials on the street air temperature is very small, with a maximum reduction of only 0.2°C in the street air temperature.