Assessing barriers for energy-efficient retrofits to derive purposive policy recommendations for the residential building sector

The European Union aims to reduce its carbon emissions by 55% by 2030, with the building sector accounting for more than one third of its total energy consumption. Therefore, it is imperative that countries with large populations, such as Germany, identify the most relevant barriers for energy-efficient retrofits (EER) to accelerate building retrofit activities. However, policymakers still lack evidence on which barriers are most important in practice, making systematic identification and prioritization necessary to avoid misdirected interventions. Consequently, this study combines a structured literature review with an online survey to derive financial, regulatory, informational and technical barriers empirically assessing their real-world relevance in a survey of 64 building experts from eight different professions using eight quantitative and 14 qualitative questions. This analysis leads to 25 policy implications that provide policymakers with actionable guidelines. Our findings show that experts perceive financial and regulatory barriers as most critical, calling for grant-based subsidies, better tax incentives, legally fixed funding terms, and less bureaucracy, particularly for retrofits of recently inherited buildings. Informational and technical challenges remain significant, with demands for a central coordination office, improved knowledge sharing, and the adoption of smart metering, AI-based analytics, and digital assistants to support decision-making. By aligning academic synthesis with stakeholders’ priorities, this study offers a structured approach to overcoming EER barriers in Germany and presents transferable insights for other countries.