Assessing the influence of neighbourhood-scale vertical greening application

Abstract

The warming climate is expected to increase environmental thermal loading on urban buildings. Green infrastructure enhancements have been widely supported as a means to address the resulting heat-related risks, with the challenge of realising enhancements in densely built cities necessitating the consideration of vegetated architectural features. Early efforts promoted horizontal greening, although in recent years ‘vertical greening’ has gained increased prominence. This paper examines the hypothesis that the wider implementation of the latter typology could serve to enhance urban climate resilience, and does so by applying an analysis pathway including the coupling of a novel one-dimensional vertical greening model (VGM) with an urban climate simulation framework to estimate the microclimate and energy-use implications of neighbourhood-scale vertical greening. The simulation results highlighted immediate thermal relief to canyon pedestrians, as well as net annual space-conditioning energy savings for the canyon buildings. These benefits, however, were modest, with a relatively pronounced influence offered for the urban neighbourhood than suburban, and with the living wall category than green facade application. Although the annual savings present potential for the wider implementation in temperate climates, the influence is insufficient to offer it as an exclusive solution, with any widescale application also requiring assessment against other ecosystem benefits and maintenance costs. Practice relevance The study contributes to the evidence base supporting both policy and practice targeting the delivery of green infrastructure enhancements, by presenting evidence that addresses widescale evergreen vertical greening application potential in temperate climates. It emphasises the need for key decision-makers considering such strategies to acknowledge the magnitude of thermal and energy-use benefits that can be reasonably expected, and identifies the most appropriate application typology and siting to prioritise. Finally, the study demonstrates the application of a novel VGM-coupled analysis pathway, which allows for such considerations to be frontloaded to building and urban design approaches. This in turn will offer technically sound reasoning when specifying such strategies and prevent costly failures of future installations.