Architectural Green Infrastructure: Enhancing habitat provision and climate regulation in urban environments using vegetated building envelopes.
Authors:   , MacKinnon Maggie 
Published: July 2024

<p><strong>As urban environments expand and densify, their destructive habitat loss and degradation impacts will continue to worsen the interlinked issues of global biodiversity loss and climate change. While protecting pristine natural habitats remains essential to biodiversity conservation efforts and climate change mitigation, advancing the practices of reconciliation ecology is crucial to addressing habitat loss and degradation within cities. Increasing the amount of vegetated habitat and the essential ecosystem services it provides is crucial to stopping/reversing species loss and improving resilience to climate change impacts in urban environments. Though current reconciliation ecology and climate change adaptation practices are restricted by limited ground-level space, vegetated building envelopes could present an opportunity to utilise the abundance of building envelope surfaces in cities for quality vegetated habitat and the species it supports. This research seeks to address the gaps in knowledge related to the role vegetated building envelopes could play in providing quality, connected habitats for native species in cities while enhancing urban climate regulation. Because habitat provision (habitat quality, biodiversity, etc.) is rarely measured at the same time as climate regulation (cooling, rainfall management, etc.), the relationship between these two ecosystem services has not been well characterised or quantified at the building or urban scale for vegetated building envelopes. The overall goal of this research is to identify and optimise the co-benefits between habitat provision and climate regulation for vegetated building envelopes at both building and urban scales. The overarching question for this research is: how can vegetated building envelopes optimise the co-beneficial relationship between habitat provision and climate regulation outcomes and contribute to reconciliation ecology and climate change adaptation practices in urban environments? Site and species specificity are important for research related to biodiversity and ecosystem services; therefore, central Wellington, Aotearoa New Zealand, was selected as a case study for this thesis. Four endemic birds in the study area were selected as the focal species due to their ecological importance. Interviews with local ecological experts were first conducted to refine the methodological approach and gain insights into the behaviours of and threats to the study species. With the aim of improving the quality and diversity of living wall habitats for native species while enhancing their cooling and rainfall management effects, this thesis used an experimental living wall setup, with supplemental simulation research, to measure a number of habitat provision and climate regulation indicators. With the aim of enhancing urban habitat connectivity for native species and flood mitigation using vegetated building envelopes in the areas where they are most needed, GIS-based spatial analyses were used to assess habitat connectivity and flood mitigation in the study area based on current and proposed green infrastructure networks. An evidence-based design approach was used to identify co-benefits between vegetated building envelope design strategies for habitat provision and climate regulation at both the building and urban scales.</strong></p><p>This thesis contributes to advancing reconciliation ecology practices at the building scale by identifying design strategies that optimise the co-beneficial relationship between habitat provision and climate regulation services for living walls: (a) plant communities with high leaf coverage and above-ground biomass; (b) deep, mixed-media substrates; and (c) irrigation regimes that facilitate high transpiration rates. Though they do not contribute to co-benefits between habitat provision and climate regulation, several other important features were identified to optimise habitat provision (fauna features and pest control) and climate regulation (extra insulation, air gap, vapour barrier, and gutters and cisterns). At the urban scale, key sites for implementing vegetated building envelope networks to enhance habitat connectivity and flood mitigation were found to share the common characteristics of being primary transportation arteries located near the outlet of watersheds and lined by mixed-use/commercial buildings. A more holistic approach to designing vegetated building envelopes that considers multiple target species and ecosystem service co-benefits could enhance their performance and uptake in urban environments, helping cities transition into more biodiverse and climate-resilient places. Advancing the practices of reconciliation ecology will be crucial to stopping/reversing the destructive relationship between urban environments and the interlinked issues of biodiversity loss and climate change.</p>