A mathematical model for a rapid calculation of the urban canyon albedo and its applications

Abstract

Urban canyon albedo (UCA) is a primary indicator used to evaluate the impact of urban geometry on radiation absorption. A rapid and effective theoretical calculation for the UCA is helpful in urban design. This research establishes a simplistic but robust mathematical model for calculating the UCA. The model was validated using prior observational studies showing that the maximum root mean square error (RMSE) is 0.03, and the minimum Pearson correlation coefficient (r) is 0.63. The model was then used to evaluate the influence of urban canyon geometry and materials on UCA. The results show that the canyon aspect ratio controls the UCA, especially when the canyon aspect ratio is less than 4. Furthermore, high-albedo facades can effectively increase UCA, and high-albedo pavements are recommended only if the urban canyon aspect ratio is less than 1. Finally, the solar performance of urban canyons on an urban scale was estimated by combining our model with digital elevation model (DEM) data. This study can be used in urban planning to estimate the radiation performance of an urban canyon quickly before full-scale urban thermal environment simulation.