Embodied Carbon Reduction Performance in the Adaptive Reuse of Existing Public Buildings: A BIM-Based Life Cycle Assessment Framework

Adaptive reuse can preserve carbon-intensive building components while avoiding material production associated with demolition and reconstruction, but its carbon benefit depends on structural retention, retrofit intensity, and future replacement cycles. This study develops a BIM-based life cycle assessment framework for 20 existing public buildings evaluated under adaptive-reuse and demolition-and-reconstruction scenarios. Autodesk Revit 2025 and Dynamo 3.2 are used to construct element-level material inventories, and openLCA 2.4 with ecoinvent 3.10 quantifies emissions across A1–A5, B4, and C1–C4 over 50 years. Illustrative analytical results show that adaptive reuse decreases embodied carbon from 842.3 ± 78.6 to 470.0 ± 61.4 kg CO₂e/m², giving a mean saving of 44.1 ± 5.8%. Structural retention contributes 59.8 ± 7.1% of avoided emissions and is the strongest predictor of carbon saving performance (β = 0.671 ± 0.112, p < 0.001). Monte Carlo analysis produces a median saving rate of 42.8% with a 95% uncertainty interval of 31.6–53.7%. The framework provides a reproducible basis for carbon-informed public-building renewal decisions.