conserVatIve and SustainAble methodoloGiEs for the Energy renovation of historic buildings - ENVISAGE

Recent advancements in environmental strategies for cultural heritage emphasize energy sustainability and reducing emissions, aligning with the EU’s 2050 climate neutrality goal under the “Green Deal”. Key objectives include decarbonizing energy, improving building efficiency, and enhancing public transport. Mediterranean EU countries face challenges, with 75% of buildings energy inefficient, leading to energy poverty. This PhD thesis focuses on energy renovation of buildings through the creation of methodologies and approaches that consider the “worst case scenario”, i.e., the case of historic buildings. The broader aim is to find a methodology which can mitigate environmental impacts while preserving the historic significance. The thesis comprises three main topics. The first details the innovative ENVISAGE methodology combining Life Cycle Assessment (LCA) with the nearly Zero Emission Refurbishment (nZER) framework, emphasizing “Planned Maintenance” to extend renovation lifespans. Enhancing energy efficiency in buildings is crucial for reducing demand and embodied carbon through sustainable interventions. The ENVISAGE method assesses the environmental impact of these interventions while preserving building aesthetics, introducing the Embodied Impact of Intervention (EII) metric, which evaluates Global Warming Potential (GWP), Primary Energy Non-Renewable (PE-NRe), and net-Fresh Water (FW). This approach aids stakeholders in selecting sustainable options for existing structures, demonstrated in a benchmark study on masonry wall components across varying visual impacts over 100 years. A direct link between GWP and PE-NRe was found, while FW's relationship with other indicators is complex, influenced by material production. High GWP was noted in scenarios using Nature-Based Solutions and Building-Integrated Photovoltaic panels, significantly exceeding those without mitigation strategies. The visual impact of interventions may not correlate with EII, highlighting the importance of using recycled materials in Low-Income Countries to improve energy efficiency and aid in achieving Sustainable Development Goals. The second part explores the TEnSE approach, a decision-making tool for selecting thermal insulation materials in renovation projects, focusing on Technical, Environmental, Safety, and Economic factors. Common materials like cellulose fibers and mineral wool are preferred for their cost-effectiveness, especially in Italy, Norway, and Portugal, although alternatives like cork and wood fibers are chosen for their environmental benefits. While thermal insulation enhances energy efficiency and sustainability, it cannot solve energy challenges alone. A standardized methodology for comparing thermal performance across European countries is needed, as well as addressing technical challenges and ensuring adherence to technical data sheets for effective material use. The final section highlights the creation of Key Performance Indicators (KPIs) to evaluate energy renovation processes using the PESTEL framework (Political, Economic, Social, Technological, Environmental, Legislative), particularly for historic buildings. The thesis aims to identify KPIs that aid in retrofitting decisions, analyzing 59 papers on historic renovation projects. Key findings include that Political aspects are underrepresented in literature due to fewer real renovation cases; the Economic interest has decreased, though it remains vital for financial feasibility; the Social domain focuses on user well-being (e.g., thermal comfort) and preserving cultural significance; the Technological domain is linked to energy and environmental sciences; the Environmental assessments often use Life Cycle Assessment (LCA) but lack uniform methodologies; the Legislative considerations are most thoroughly addressed, highlighting the importance of regulation compliance. The PESTEL Analysis promotes a holistic approach to energy retrofits, balancing heritage significance with environmental goals. KPIs were developed from the PESTEL domains for a comprehensive evaluation, which were then refined and applied to a historic building case study in Rome, confirming that legislative factors are paramount in maintaining historical integrity. The three key outcomes should be analyzed collectively to understand the ENVISAGE framework, which aligns with the upcoming Energy Performance of Buildings Directive (EPBD) 2024 and the European Standard EN 16883:2017 “Conservation of cultural heritage - Guidelines for improving the energy performance of historic buildings”. This includes establishing new KPIs for assessing energy efficiency and integrating them into the standard. The ENVISAGE framework serves as a foundation for a comprehensive study on future developments, using the methodology and new KPIs within a legislative context to explore innovative research aspects.