Integrated BIM–LCA–optimization for decarbonizing curtain wall façades under carbon pricing uncertainty

Curtain wall façades contribute substantially to upfront embodied carbon in new buildings, and early design choices constrain long-term decarbonization options. Many jurisdictions are introducing embodied-carbon caps or carbon pricing; designers still lack tools that link these policy drivers to early façade decisions. This study develops an integrated concept-stage workflow linking BIM-based curtain wall modelling, life-cycle carbon assessment, a façade circularity indicator, discounted life-cycle costing, deterministic optimization and Monte Carlo uncertainty analysis. Façade quantities were derived from eight curtain wall panel models in Autodesk Revit, embodied-carbon factors from Australian Environmental Product Declarations (EPD) and the Environmental Performance in Construction (EPiC) database in One Click LCA, and private-cost from the project’s dataset and normalized to AUD/m². Deterministic optimization indicates that carbon prices of approximately 100–420 AUD/tCO₂e shift optimal solutions from aluminium-intensive to higher-circularity timber-hybrid systems, reducing façade life cycle global warming potential (LC-GWP) from approximately 380–400 kgCO₂e/m² to 270–300 kgCO₂e/m² with modest cost increases. Monte Carlo simulations confirm that outcomes are largely governed by the carbon price level rather than price-path uncertainty, with limited cost risk. The workflow enables design teams to test façade options under explicit policy scenarios and align concept-stage decisions with net-zero and circular-economy goals.