Mitigating intensity of urban heat island by better understanding on urban morphology and anthropogenic heat dispersion. (June 2020)

• Record Type: Journal Article
• Authors: Yuan, Chao; Adelia, Ayu Sukma; Mei, Shuojun; He, Wenhui; Li, Xian-Xiang; Norford, Leslie
• Is Part Of: Building and environment. Volume 176(2020)
• Publication Date: 2020-06
• Subjects: Anthropogenic heat dispersion -- Semi-empirical model -- CFD simulation -- Urban planning -- GIS mapping; Buildings -- Environmental engineering -- Periodicals; Building -- Research -- Periodicals; Constructions -- Technique de l'environnement -- Périodiques; Electronic journals; 696
• DOI: 10.1016/j.buildenv.2020.106876
• Languages: English
• ISSNs: 0360-1323

Abstract

Abstract: Anthropogenic heat is one of the key factors that causes intensive Urban Heat Island (UHI) due to its direct impact on ambient temperature in urban areas. Stagnated airflow due to closely packed tall buildings causes weak dilution and removal of anthropogenic heat. Consequently, research is critically needed to investigate the effect of urban morphology on anthropogenic heat dispersion and provide effective planning strategies to reduce UHI intensity, especially at the extreme scenarios, such as with very low wind speed and high heat emission. This study provides scientific understanding and develops a Geographic Information System (GIS)-based modelling tool to support decision-making in urban planning practice. We start from a computational parametric study at the neighbourhood scale to investigate the impact of urban morphology on heat dispersion. Site coverage ratio and frontal area density are two urban morphological parameters. Ten parametric cases with two heat emission scenarios are designed to study representative urban areas. Furthermore, based on the energy conservation within urban canopy layers, we develop a semi-empirical model to estimate spatially-averaged in-canopy air temperature increment, in which the exchange velocity between street canyons and overlaying atmosphere is estimated by the Bentham and Britter model. The performance of new model is validated by cross-comparing with Computational Fluid Dynamics (CFD) results from the parametric study. By applying this new model, the impact of anthropogenic heat on air temperature is mapped in residential areas of Singapore for both long-term annually averaged and short-term extreme low wind speed to improve urban climate sustainability and resilience. Highlights: Urban morphology significantly affects anthropogenic heat (AH) dispersion. Air temperature increment caused by AH can be estimated by site coverage ratio. GIS semi-empirical model is developed to support decision making in planning. Model performance is evaluated by cross-comparing with CFD simulation. The effect of AH on air temperature in Singapore residential areas is mapped.