Numerical Simulation of Local Climate Zone Cooling Achieved through Modification of Trees, Albedo and Green Roofs—A Case Study of Changsha, China

Abstract

By exploring the cooling potential of tree quantity, ground albedo, green roofs and their combinations in local climate zone (LCZ)-4, LCZ-5, and LCZ-6, this study focuses on the optimum cooling level that can be achieved in open residential regions in Changsha. It designs and models 39 scenarios by integrating in situ measurement and ENVI-met numerical simulation and further compares cooling effects of various combinations of the cooling factors. The results show that (1) an increased number of trees and higher albedo are more effective compared to green roofs in reducing summer potential temperatures at street level (2 m high) in three LCZs. Negative correlations are observed in the pedestrian air temperature with trees and ground albedo; (2) the effects of cooling factors vary among different LCZ classes, with the increased 60% more trees leading to lower outdoor temperatures for LCZ-4 (0.28 °C), LCZ-5 (0.39 °C), and LCZ-6 (0.54 °C), while higher albedo of asphalt surface (increased by 0.4) is more effective in LCZ-4 (reaches to 0.68 °C) 14:00, compare to LCZ-5 (0.49 °C) and LCZ-6 (0.38 °C); (3) applying combined cooling methods can provoke air temperature reduction (up to 0.96 °C), especially when higher levels of tree quantities (increased by 60%) are coupled with cool ground materials (albedo increased by 0.4). The results can contribute useful information for improving thermal environment in existing residential regions and future residential planning.

Impact of 2050 tree shading strategies on building cooling demands

“…In all future scenarios, but especially in TBS and MTC, taller buildings (predominantly mixed use, and with a larger footprint) underperformed in terms of tree-based reductions in total SRA and BCED. This observation is supported by other modelling research noting lower cooling effects in areas with tall buildings despite increasing trees (by 30% or 60%; Chen et al 2020). The lower tree shading impact for these taller/larger buildings in TBS and MTC can also be attributed to the generally smaller tree sizes associated with the climate-adapted species used.…”

Perceived Quality of Urban Wetland Parks: A Second-Order Factor Structure Equation Modeling

“…Urban nature has been widely recognized as an important part of urban infrastructure providing a variety of ecosystem functionalities and services, contributing to sustainable urban development [5]. Findings of empirical investigations have indicated that the presence of natural areas and green infrastructures in cities has the potential to fend off the adverse challenges on vulnerable urban environments and positively affects the life quality of inhabitants [6][7][8][9][10][11]. Consequently, investigations on people's comfort perception related to urban nature and green infrastructure grows steadily [12][13][14][15].…”

Ambient temperature modelling from surface characteristics and associating urban morphology with thermal discomfort

“…A total of 168 datapoints Surface parameter extraction from satellite images LST patterns have been linked with air temperature by various researchers (Anbari et al, 2019;Hooker et al, 2018;Unger et al, 2009). Few studies have elaborated the effects of albedo properties and vegetation cover on heat retention and dissipation (Akbari et al, 2001;Chen et al, 2020). Based on such previous observations, four parameters were selected as independent variables to model maximum T a .…”