Designing for nature doesn't cost the Earth

Jacinta Ellesse Humphrey , Holly Louise Kirk , Victoria Cook, Dom Blackham, Matthew Bradbury, James Horwood, Celeste Morgan, Clancie Shorter, Ray Verratti, Bethany Kiss, Sarah Bekessy

1. A key barrier to the development of nature positive cities is the unknown cost of implementing novel urban design elements. Strict budgets and government approval processes make it challenging for developers to trial new approaches, meaning most developments rarely deviate from ‘business-as-usual’ (BAU). Further research is urgently needed to overcome this barrier to innovation and help mainstream concepts like Biodiversity Sensitive Urban Design (BSUD).
2. We sought to estimate the relative cost of BSUD actions intended to enhance habitat and mitigate threats for native fauna, while also providing health and well-being benefits for people. We shortlisted 18 actions proposed for public greenspaces including alternative planting designs, habitat analogues and elevated watering points for wildlife. We employed expert elicitation to estimate the cost of implementing these actions in a greenfield community development in peri-urban Melbourne, Australia. We recruited six practitioners whose expertise spanned engineering, landscape architecture, urban planning and design, integrated water management, urban heat mitigation and public lighting. Participants were primed with background information and asked to independently assess the feasibility, opportunities and challenges of each action, and estimate the relative cost of implementing each action compared to BAU. We then facilitated an online workshop where participants were encouraged to reach a consensus on the relative cost of each action. We also conducted a literature review on the potential co-benefits of integrating nature into urban developments.
3. Our experts concluded that 15 of 18 actions (83%) were likely to cost the same, or only slightly more, than a BAU approach. Actions that focused on creating diverse habitat structure were deemed particularly valuable, as they were likely to result in biodiversity benefits and were estimated to cost the same as BAU.
4. Cost-benefit analysis should also consider the substantial co-benefits of prioritising nature; we summarise these benefits and argue that their economic valuation could further motivate the uptake of BSUD.
5. These results suggest that BSUD is both feasible and relatively affordable to incorporate into a community development. We conclude that cost need not be a barrier to innovation in the design of urban spaces that benefit people and nature.