INFLUENCE OF PAVEMENTS ALBEDO ON THERMAL CONDITIONS IN URBAN CANYONS: STUDY IN A REDUCED SCALE MODEL

Abstract

The urban climate is directly influenced by the growth of the cities. By means of infrastructure expansion, the road network becomes a constituent part of this scenario and proportionally responsible for the interferences in local microclimate. This way, urban layout and morphology should promote ventilation, shading and temperature control of the built environment in order to reduce climatic effects, such as the urban heat islands. Thus, this research seeks to analyze the effect of pavement albedo on temperature reduction of urban canyons, through a reduced scale model. The method consists of monitoring thermal variables in a physical model. This model was constructed with four different colours of pavement 8 cm thick, 120 cm wide and 500 cm long, separated laterally by 40 cm and 80 cm high barriers, in two urban configurations. The material taken as reference will be the flexible dark asphalt pavement, in relation to the interlocking semi-permeable concrete floor, in the gray, red and graphite colours. The choice of asphalt material as the reference is justified by its wide use in built urban space of Brazil, which provides a better characterization of the real environment. In the instrumentation step, anemometers and hygrometers were installed to evaluate the air movement and the relative humidity of the period; and thermocouples to collect surface temperature, air temperature, and radiant temperature data at different levels and morphologies. Through the results analysis, it is seen that the orientation of the canyon, the increase of the aspect ratio, albedo differences and the surface moisture content, can cause temperature variations in the built environment. Finally, the albedo of urban pavements can contribute to the mitigation of urban heat islands.