A System Thinking Approach to Circular-Based Strategies for Deep Energy Renovation: A Systematic Review

Over 85% of buildings in the European Union were constructed before 2001, contributing to energy inefficiencies, material waste, and increasing socio-economic disparities. While deep energy renovations (DER) are critical to EU climate goals, their implementation remains hindered by financial, regulatory, and social barriers. Integrating circular economy (CE) principles into DER offers a pathway to enhance resource efficiency and sustainability yet requires a systemic understanding of feedback dynamics. This study applies a systems-thinking approach to examine the interdependencies influencing CE-DER implementation. Five thematic clusters—technical enablers, economic and policy barriers, social sustainability factors, environmental considerations, and digitalization for climate resilience—are identified, informing the development of causal loop diagrams (CLDs). The CLDs reveal key reinforcing loops such as innovation investment, policy learning, stakeholder co-design, operational efficiency, and balancing loops, including certification bottlenecks, financial fragmentation, and digital resistance. The findings suggest that CE-DER success relies on activating reinforcing dynamics while addressing systemic constraints through coordinated financial incentives, ethical digitalization, and inclusive governance. By visualizing interdependencies across technical, social, and policy domains, the feedback-oriented framework developed provides actionable insights for advancing socially equitable, resource-efficient, and climate-resilient renovation strategies.