Understanding the global warming potential of circular design strategies: Life cycle assessment of a design-for-disassembly building

Targets for carbon emissions and energy use are set within the built environment to drive change and reach net-zero by 2050. Meanwhile, circular design strategies, including design-for-disassembly (DfD), are promoted to address waste production, raw material usage and lack of reuse, however their environmental impacts are not always measured. Therefore, a process-based life cycle assessment of a DfD building has been performed to assess its environmental impacts across 18 impact categories. The results are compared against industry target values for global warming potential (GWP100), energy use and material reuse to assess whether current targets are effective for assessing a broad range of sustainability principles. For the product and construction stages, the rank order of the main contributors to GWP100 is representative of 8 of the 18 impact categories. The superstructure and building services account for at least 75% of the total impacts for product and construction stage across all impact categories. Compared against industry target values, the case study building has a GWP100 that is 26% below baseline industry target values for the product and construction stage, operates using less energy than targets for education and office buildings, and has been designed to enable the reuse of 65%, by mass, of the substructure and superstructure at end-of-life. Current target values focus on driving reductions in GWP100 while maintaining low operational energy use, but do not fully capture the benefits from increasing material reuse through circular and DfD strategies. Patterns within assessed impact categories need to be further investigated to develop target values capable of representing a range of impact categories and material circularity.