Dynamic multi-factor approach for deriving embodied carbon limit of building structures

Establishing scientifically grounded embodied carbon limits is essential for guiding low-carbon structural design and translating macro-level decarbonization targets into actionable regulatory parameters. Here we propose a dynamic, multi-factor methodology for deriving embodied carbon limits of building structures, accounting for evolving carbon budgets and shifts in their allocation to embodied carbon-related activities in regions with a transitioning construction sector. This methodology integrates top-down budget decomposition with bottom-up benchmarking to respectively determine upper and lower bounds of embodied carbon limits for new construction, renovation, and maintenance. Furthermore, multi-factor adjustments are introduced to customize limits according to building type, regulatory stringency, regional conditions, and lifecycle design requirements. The proposed methodology is demonstrated through an analysis of urban residential building structures in China from 2026 to 2060, which reveals a declining trend in embodied carbon limits over time, and provides reasonable limit ranges corresponding to China's Five-Year Plans (FYPs), e.g., 320.8–360.8 kg CO₂/m² for new construction, 0.96–1.08 kg CO₂/(m²·year) for maintenance, and 56.3–63.0 kg CO₂/m² for renovation with a moderate level of regulation during the 2026–30 FYP. The analysis also highlights the benefits of construction management in providing a buffer period for limit relaxation, examines the impact of regional disparities on carbon mitigation feasibility-based adjustments, and offers recommendations for low-carbon lifecycle design to ensure compliance with mitigation targets while providing further design flexibility.