Urban heat Island effect: Thermal response from different types of exposed paved surfaces

Pavement surface temperature could reach up to be 20-30°C higher than the air temperature due to solar-energy absorption by pavement during the daytime, especially in hot climates. The heat energy absorbed by the paved surfaces is then stored inside and subsequently released as heat into the atmosphere, mostly at night. This interactive process increases the intensity of the Urban Heat Island effect: a phenomenon whereby urban regions experience warmer temperatures than their rural surroundings. In this paper, different conventional and modified paved surfaces (both cement and asphalt bound) have been reproduced and tested in exposed environment to evaluate and compare their thermal performances by calculating thermal parameters such as such as emissivity, albedo, and solar reflective index. The testing was conducted with a thermal infrared camera, a pyranometer, a weather station and with a set of thermocouples. The results showed that concrete releases internal temperatures slowly during the day and asphalt material releases superficial heat quicker than the concrete. The phenomenon of heat storage and release was also evaluated by artificial heating/cooling in the laboratory environment. It was found that painted (yellow) paved surfaces generate a positive, although a different, reflective and cooling effect on both asphalt and concrete material. The extent of respective painted surfaces could be considered in urban paving design andmanagement to reduce the Urban Heat Island phenomenon.