Approaches for the Renovation of Reinforced Concrete Building Envelopes: Technical Challenges and Future Trends

The renovation of existing reinforced concrete (RC) buildings is essential to reduce the environmental impact of the existing building stock while improving its energy performance and resilience. However, existing renovation strategies are often addressed separately, making it difficult to compare their capabilities and limitations. This study presents a comprehensive review of renovation approaches for RC building envelopes, with particular emphasis on Southern European building stocks, where thermal and seismic deficiencies frequently coexist. The review examines three main renovation strategies: demolition and reconstruction, energy renovation, and combined seismic and energy renovation, and analyses representative systems identified through a structured literature review. A comparative analytical framework was developed based on four dimensions: functional integration, structural role, degree of prefabrication, and adaptability to existing building conditions. The analysis reveals a clear transition from conventional insulation-based interventions towards multifunctional and system-integrated envelope solutions. While prefabricated systems improve construction industrialization and production scalability, integrated seismic–energy solutions provide higher functional performance but require greater project-specific adaptation, reducing their large-scale applicability. The review also identifies the limited integration of spatial and architectural transformation within current renovation strategies. The proposed framework provides a structured basis for comparing existing solutions and identifies key challenges and future research directions for the development of more adaptive, industrialized, and integrated renovation systems.