Regenerative Architecture: Carbon Sequestration and Habitat Provisioning through Building Design

The urban built environment is one of the most significant contributors to global carbon emissions, and the annual increase in atmospheric carbon dioxide is one of the core environmental issues driving global climate change. Rapid urbanisation is also causing natural ecosystems to be replaced with a heterogeneous urban matrix and patches of built-up areas, resulting in fragmentation, habitat degradation, and damage to biodiversity and ecosystem functioning. A fundamental rethinking of architectural and urban design could move towards the halting of ecosystem degeneration and an increase in their regenerative capacity. As the world is becoming increasingly urbanised, there is a growing need to incorporate nature-based solutions into building design to minimise or offset the harm they create. Increasing green spaces within urban built environments through building-integrated vegetation, such as green roofs and green walls, is primarily adopted for the purposes of stormwater management, evapotranspiration cooling and shading. Biodiversity conservation and carbon capture are often generated as a by-product of integrating vegetation into building design and are not the main focus. This research integrates vegetation into architecture by emulating the natural ecosystem to create a built ecosystem that could generate quantifiable carbon sequestration (the process of actively removing CO2 from the atmosphere) and habitat provisioning (providing living space for plants and animal species). On the one hand, building-integrated vegetation and urban green spaces have the potential to sequester atmospheric carbon and store it in the above- and below-ground biomass. On the other hand, these same green spaces, if strategically vegetated, provide important habitats for a wide variety of species, including insects, birds, and mammals and can act as potential stepping stones which connect habitat patches and reduce fragmentation. The relationship between these two ecosystem services is multifaceted and complex dependent upon vegetation type, substrate type, environmental conditions, and management strategies. This research thus explores the relationship between two aspects of regenerative design, i.e., carbon sequestration and habitat provisioning, to address the interrelated issues of climate change and biodiversity loss. Such projects that aim to regenerate urban ecosystems through architectural interventions need a context-based design evolution approach, as ecology is specifically location-dependent. The CO2BIRD (Carbon sequestration and Biodiversity-Integrated Regenerative Design) framework, prepared as an outcome of this research through a combination of literature review, quantitative and qualitative research methods, considers this context-based approach through holistic thinking: seeing a building and its surroundings as a unified system. And because biodiversity is location-specific, this research explores the practical implementation of the CO2BIRD framework by conducting a case study of an existing urban built environment, i.e., Wellington City, New Zealand. Birds are regarded as the primary species for biodiversity monitoring in urban built environments in New Zealand and globally due to their ease of identification and significant role in ecosystem functioning. However, this research focused on the keystone bird species found in Wellington, which are tūī, kererū, korimako and hihi, due to their greater ecological impact than other bird species. This CO2BIRD framework includes research-led data-gathering approaches to understanding the ecological, cultural, climatic and legal contexts. A catalogue of strategies is prepared that compares each strategy in terms of its carbon sequestration and habitat provisioning potential and the mutual benefits they provide to humans and nature. The indicators, which consider the dynamics of carbon sequestration and habitat provisioning ecosystem services, are identified to quantify the carbon sequestration rates and habitat provisioning levels, and guide the design development and implementation. Post-occupancy monitoring and management guidelines are also suggested, introducing building occupants to a regenerative culture and adaptive management approach that emphasises the need for flexibility and openness, ensuring that the built environment is able to adapt to the impacts of climate change. The results of this research encourage leading-edge professionals and decision-makers to concurrently design for enhancing biodiversity and decarbonising buildings through integrating vegetation. The strategies defined in this research could be upscaled to apply at regional, national and global levels and could be applied to different ecological, climatic and cultural contexts. The benefits are greatest when these approaches and strategies are integrated into broader regional-level green infrastructure networks and thus avoid further biodiversity loss and mitigate the impacts of climate change on the urban built environment.