An integrated framework for enhancing energy efficiency and environmental sustainability in historic buildings and sites: A comprehensive overview of policy, certification protocols and research perspectives

Historic buildings embody the cultural identity of cities and societies, making their preservation a fundamental component of sustainable urban development. At the same time, current energy transition targets and greenhouse gas reduction goals require substantial improvements in the performance of the existing building stock, including heritage assets. This dual imperative generates a persistent tension between sustainability objectives and conservation requirements. This paper explores this challenge, through a comprehensive analysis of policies, environmental certification protocols, scientific research trends and real-world case studies, with a particular focus on the Italian territory, which is a relevant and significant context with respect to built cultural heritage. The results reveal a fragmented regulatory framework where the integration of energy efficiency into heritage conservation has gained structured attention only in recent years, particularly since 2015, mainly through non-binding guidelines. Among the 32 analyzed papers and case studies, 44% are 19th–20th century buildings mainly located in Central Italy, though they often lack in-depth historical and environmental analysis. The study proposes a replicable and integrated framework aimed at aligning heritage conservation principles with energy performance, environmental sustainability, and comfort objectives, advocating for experimental and numerical methods to design innovative and compatible retrofit strategies. By bridging policy analysis, sustainability assessment tools, and applied research, this study contributes to advancing a holistic approach to the energy and environmental retrofit of historic buildings and sites.