Beyond Carbon: Integrating Biodiversity Impact Assessment in Building Design Practice - A tool to evaluate off-site biodiversity impacts of the built environment

Abstract

The increasing focus on decarbonisation in the building sector has intensified the use of bio-based construction materials. However, climate-driven strategies do not fully capture broader environmental consequences, particularly regarding biodiversity loss. This thesis investigates the relationship between biodiversity impacts and global warming potential, examining how design decisions and material sourcing influence the environmental performance of buildings. A comparative case study approach is applied, assessing conventional concrete structures alongside several timber-based alternatives. The results show that reductions in carbon emissions may simultaneously increase off-site biodiversity impacts, revealing potential burden-shifting between environmental categories. At the same time, considerable variation is identified within timber-based systems, demonstrating that bio-based construction is not inherently associated with high biodiversity impacts. Cross-laminated timber (CLT) generally has higher impacts, while timber frame systems perform favourably across both carbon and biodiversity indicators. The analysis further highlights geographical sourcing as a critical factor, with Nordic and Central European timber showing substantially lower impacts than global average datasets, highlighting the importance of more detailed material considerations and structural design decisions. To explore how the biodiversity assessment can support practice, a computational tool is developed to integrate biodiversity footprint (BF) evaluations into architectural workflows. Building on life cycle assessment methods, the framework enables simplified comparison of design alternatives and identification of environmental hotspots at both building and component level, addressing the need for more accessible tools in the design process. Although constrained by methodological uncertainty and limited data availability, the study demonstrates how biodiversity considerations can support iterative evaluations and contribute to broader environmental decision-making in the building sector. Overall, the thesis shows that biodiversity impacts cannot be understood through carbon metrics alone. The study highlights the importance of integrating biodiversity as a complementary dimension in order to support more holistic sustainability strategies within the built environment.