Towards net-zero embodied carbon: Investigating the potential for ambitious embodied carbon reductions in Australian office buildings

Abstract

Embodied carbon is recognised as a major contributor to building-related greenhouse gas (GHG) emissions. In response, ambitious targets have been posed to reduce embodied carbon in the built environment, including the aspiration of ‘net-zero embodied carbon’. This research uses a life cycle assessment (LCA) methodology to explore the magnitude of embodied carbon reductions viable within a multi-storey office building in Australia. It compares a typical building with more ambitious design scenarios to determine if net-zero embodied carbon is feasible in the current context and how design, material and methological decisions impact this. The results show that upfront embodied carbon reductions of 17–45% are achieveable with ambitious design and material changes, including a full timber structure, hybrid timber-aluminium façade, reduced columns grids, straw insulation, and more. However, the magnitude of reductions is highly influenced by material data sources and methodology. Net-zero embodied carbon was achievable when considering biogenic emissions stored in timber and other biomaterials, although only temporarily, for a period of up to 19 years. In response, we propose a new term ‘temporal net-zero embodied carbon’ to identify the point in time during a building's life cycle when it can no longer be considered a temporary carbon sink. The paper concludes by highlighting the opportunties and challenges temporal net-zero embodied carbon presents in terms of transparency and reliability of metrics, the need for consistent approaches to measurement and benchmarking, and the challenges of achieving large-scale embodied carbon reductions in the office sector.