Synergistic approaches to structural and thermal retrofitting via external envelopes for existing buildings: a state-of-knowledge

Retrofitting existing masonry and Reinforced Concrete (RC) buildings remains a critical challenge in advancing both structural resilience and energy efficiency. This paper provides a comprehensive review of state-of-the-art techniques that integrate structural and thermal upgrades through interventions applied to the building envelope, with the main aim of classifying them. These multifunctional solutions may enhance structural performance while simultaneously improving thermal efficiency, particularly in regions with significant seismic risk and a rigid climate. Key innovations include − among the others − composite panels, externally bonded Fabric-Reinforced Cementitious Mortars (FRCMs), ventilated façades or with embedded insulation, and hybrid systems that combine mechanical anchorage with thermal layers. Special attention is given to the synergistic interaction between materials, emphasizing both their potential and their limitations. By coupling passive energy strategies with structural reinforcement, these approaches not only improve building performance but also contribute to sustainability objectives and compliance with evolving regulatory frameworks.