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Arboriculture & Urban Forestry Online
Volume 48, Issue 2 — March 2022

Modeling the Shading Effect of Vancouverís Urban Tree Canopy in Relation to Neighborhood Variations

Yuhao Lu, Justin McCarty, Jeri Sezto, Zhaohua Cheng, Nicholas Martino, Cynthia Girling, Adam Rysanek, Sara Barron, and Giona Matasci

Abstract: Background: Cities consume a disproportionate amount of energy for internal temperature regulation. Being able to reduce citiesí cooling load on hot summer days can decrease energy consumption while improving occupantsí thermal comfort. The urban canopy is an effective shading agent, adding cooling benefits to existing buildings and streets while providing other ecological and physiological values. Yet the building and street shading dynamic is a highly complex system that involves micro-level building components and macro-level variables. Introducing urban canopy to such a complex system creates another challenge, as urban canopy variables can also interact with buildings at both micro- and macro-levels. In order to accurately represent the urban canopy shading effect, it is necessary to account for the interactions among buildings, streets, and urban canopies. Methods: This study simulates the shading effect of urban canopy measured by aerial laser scanning (ALS) in the City of Vancouver, Canada, through the integration of a Radiance daylight simulation engine and geographic information system (GIS) data. All trees detected by ALS were included in the analysis. Results: The results indicate that street surfaces receive more solar irradiance reduction than building roofs and faÁades (i.e., exterior walls). Neighborhoods with less density and lower buildings were shaded noticeably better than areas with higher density and taller buildings. Among Vancouverís 22 neighborhoods, 2 neighborhoods, Kitsilano and the West End, demonstrated a promising sign where both building density/height and urban canopies are maintained. There was evidence of high canopy shading and high-density urban morphologies. Conclusion: Overall, this work provided an authentic canopy assessment from single building to city scale, creating opportunities to investigate intracity urban canopy variations, equality, and the balance between urban greening and urban densification.

Keywords: 3D Tree Canopy Mode; Aerial Laser Scanning; Canopy Shading; Radiance Model; Street Trees; Urban Forestry.

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