The Potential for Perennial Vines to Mitigate Summer Warming of an Urban Microclimate

Shading and evapotranspirative cooling by vegetation are important controls on moderating rise in city temperatures and mitigating urban heat islands. The purpose of this research is to evaluate the potential of Boston ivy (Parthenocissus tricuspidata) to mitigate warming of building surface temperature in an urban core. Temperature loggers were placed on vine-shaded and non-shaded walls in Toronto, Canada to collect surface temperatures over a six-month period. During peak solar access periods, average vine-shaded and non-shaded temperature differentials of up to 6.5 °C and 7.0 °C for the south and west-facing walls were measured, respectively. Predictive models were developed to estimate daily degree hour difference (DHD), a metric for capturing the temperature moderating potential of vines. At ambient air temperatures exceeding 22 °C, ambient air temperature and solar radiation were significant positive drivers of DHD. Results are important to further understanding urban plant-microclimate interactions and strategies for heat island management.