Systemic Barriers to Sustainable Building Renovation: A Life Cycle Thinking-Based Fuzzy AHP-DEMATEL Analysis

Sustainable building renovation requires understanding both the relative priority of implementation barriers and their perceived interdependence across the building life cycle. This study combines fuzzy analytic hierarchy process (AHP), fuzzy decision-making trial and evaluation laboratory (DEMATEL), and life cycle thinking (LCT). The AHP priorities for 15 barriers are derived from 30 aggregate comparison-frequency rows, each totalling 12. DEMATEL analyses a single recorded seven-barrier influence matrix; the original consensus procedure cannot be verified. Financial barriers receive the largest cluster weight (0.471), and upfront cost ranks first globally (0.157). Within the selected network, fragmented responsibilities (+0.851) and stakeholder misalignment (+0.424) have the largest net outgoing influence, while upfront cost is slightly net incoming (−0.100). Upfront cost remains first across 120 single-comparison perturbations and two alternative defuzzification conventions. Adjacent ranks and financial-node classifications are more sensitive to numerical specification and network membership. DEMATEL-based practical implications are restricted to the seven assessed barriers; no influence relationships are available for excluded payback uncertainty (F2). The framework links relative priority, conditional perceived influence and life cycle decision stages to formulate testable financing and coordination hypotheses. LCT structures whole-life interpretation without constituting a quantified life cycle assessment.