Growing Energy Conservation Through Residential Shade Tree Planting

Michelle Sawka

doi:10.32920/ryerson.14654319

Abstract

Urban residential shade trees extenuate the heating of buildings in the summertime by intercepting insolation and by evapotranspirative cooling of their immediate surroundings. By modifying location-specific climate data, and tree growth characteristics, this research adapts the Sacramento Municipal Utility District’s (SMUD) Tree Benefits Estimator for application in Toronto, Canada. This tool is then put to use modeling the energy conservation savings delivered by 577 trees planted in Toronto backyards between 1997 and 2000. This study’s results estimate that the trees contributed 77,139 kWh of electricity savings as of 2009, 54.4% of which was due to shading of neighbouring houses. This study’s findings indicate that urban residential tree planting programs should not focus exclusively on location-driven strategic planting to yield large energy conservation benefits. Instead, it is argued that priority should be given to selecting planting locations that will maximize tree survival as neighbourhood energy conservation benefits of a tree that achieves mature stature often outweigh the homeowner-specific benefit of a strategically planted tree.

Highlights

Urban dwellers often view the city as distinct and separate from nature (Hough, 1989)
After discounting for existing canopy cover, and making adjustments to estimates for air conditioning, the total cumulative energy conservation benefit delivered by the 461 surviving trees as of 2009 was 77,140 kilowatt hours (kWh) (167 kWh per tree)
During its first year following planting, the greatest energy conservation associated with a single tree was 112 kWh

Summary

Introduction

Urban dwellers often view the city as distinct and separate from nature (Hough, 1989). Concern for climate change and energy conservation have led many urban municipalities to seek approaches to land use planning that integrate ecological sustainability by encouraging the preservation and creation of resilient natural systems within their cities (Grimm et al, 2008; Dwyer et al 2003). These efforts emerge in contrast to a traditional North American perception of the urban environment as distinct from nature (Hough, 1989). Trees modify urban microclimates by altering airflow, affecting the diffusion and transport of thermal energy and water vapour (McPherson and Rowntree, 1993)

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Conclusion