Designing nature based solutions for the built environment in the future climate: a case study in Barcelona

Climate change poses significant risks to urban areas, particularly the phenomenon of urban heat island (UHI) effect, which exacerbates thermal stress and environmental degradation in densely populated cities. The Climate Change Committee (CCC) has identified rising urban temperatures as a critical challenge, with projections indicating that by 2050, 68% of the global population will reside in urban areas, further increasing vulnerability to extreme heat events. Nature-Based Solutions (NBS) provide a holistic and sustainable alternative, incorporating green infrastructure, vertical greening systems, and natural ecosystems to simultaneously address UHI impacts and enhance urban ecological balance.
This study investigates the potential of NBS in mitigating urban heat in Barcelona, a city characterized by its dense urban fabric, Mediterranean climate, and high levels of tourism. The research examines strategies for creating biodiverse urban forests, strengthening green corridors, and reducing UHI effects while advancing sustainable urban development. Employing a research-by-design methodology, this study develops urban forests as a highly sustainable development approach for future climates. The research process consists of three main stages: (1) an evaluation phase, which involves analyzing the site model for projected conditions in 2050, focusing specifically on changes in heatwave patterns. (2) a design phase, where scenarios are developed to enhance the urban environment through nature-based approaches across multiple scales, and (3) a retesting phase, involving simulation-based experiments to evaluate the effectiveness of each design strategy. Simulations compare the environmental impacts of the enhanced nature-based design scenarios, both with and without the inclusion of vegetation. The findings show the importance of developing nature-based solutions in the architecture and planning strategies, as a means of promoting more sustainable and resilient cities in the face of global climate change. The findings of this study underscore the urgency of adopting innovative approaches to urban regeneration that leverage nature-based solutions to enhance the connection between nature, humans, and cities.