Advancing Circular Economy strategies in urban construction using a combined MFA and LCA approach

According to the IPCC, the building sector was responsible for around 21% of global greenhouse gas (GHG) emissions in 2019, with 18% of those attributed to embodied emissions, calling for urgent actions in this sector to meet decarbonization goals and reach net-zero emissions by 2050.
The growing share of embodied energy and emissions due to the increase in building efficiency
highlights the need for a transition from the current linear "build, use, demolish, dispose" model in the construction sector to a circular approach, entailing promising potentials regarding reduction of primary energy and resource consumption, waste generation, and associated GHGemissions.
This work aims to address a critical research gap regarding the application of life cycle assessment (LCA) in decision-making processes in the construction sector. It provides reliable assessments of environmental benefits associated with circular economy (CE) strategies, particularly the recycling and reuse of construction materials.
The modeling approach developed within the ERA-NET project CREATE is a scenario-based
assessment methodology combining a Material Flows Analysis (MFA) with a LCA model. The MFA component quantifies material flows for different construction and demolition scenarios, cocreated with local stakeholders including urban developers, construction companies, and city representatives. The LCA performed using OpenLCA, compares the environmental impacts of different end-of-life (EOL) scenarios and different shares of secondary materials in the
construction scenarios for the estimated flows obtained with the MFA.
The development of both circular economy and business-as-usual (BAU) scenarios is driven by
technical, economic, governance, regulatory, and social factors. The BAU scenario serves as a
benchmark for comparing the developed circular scenarios in terms of energy consumption, raw material saving, and CO2 emissions reduction. The assessment focuses on on-site recycling and reuse of building materials and components new construction and renovation works. Besides, the model also captures the benefits of material reuse and recycling beyond system boundaries, accounting for diverse applications for secondary materials. The technical scope includes processes from transportation, treatment, and disposal of waste for the EOL modeling on the one hand, and raw material extraction, building material manufacturing, and transportation to construction sites for the new construction modeling on the other.
The proposed methodology is being developed and tested within the framework of several case studies established for four cities within CREATE. The first two case studies examined in this work refer to urban redevelopment projects in Rennes Métropole and Vienna