Energy-Efficient Rehabilitation of Buildings: Mitigating Heat Loss and Structural Risks in Pre-1990 Constructed Structures

Buildings constructed prior to 1990 are characterized by significant energy inefficiencies, predominantly due to inadequate thermal insulation, inefficient heating systems, and deteriorated façade elements. These deficiencies lead to considerable heat losses through exterior walls, windows, and terrace areas, resulting in elevated heating costs during the winter season and suboptimal indoor thermal comfort. Additionally, the structural integrity of these buildings is often compromised, increasing the risk of collapse due to the degradation of construction materials. This study analyses 20 educational buildings distributed across Romania, constructed before 1990, to evaluate their energy performance and identify patterns of inefficiency. Using advanced statistical methods, the research highlights key trends, including correlations between building geometry, material performance, and energy consumption. The findings underscore the critical need for comprehensive thermal rehabilitation, targeting a reduction in annual specific heat consumption for heating by an average of 30%, with projected payback periods of 5–7 years for key interventions. The paper explores a suite of energyefficient rehabilitation strategies, including wall and roof insulation, the upgrade of windows to low-E glazing, and the optimization of heating systems. The analysis incorporates geographic variations, demonstrating how regional climates influence energy performance and rehabilitation priorities. Results indicate that such interventions not only enhance energy efficiency and occupant comfort but also contribute to significant reductions in greenhouse gas emissions, aligning with national and European energy directives. By addressing both energy and structural deficiencies, this paper provides a robust framework for sustainable rehabilitation practices, offering actionable insights for policymakers, building owners, and stakeholders in the energy and construction sectors. The proposed measures aim to ensure the longevity, safety, and energy efficiency of pre-1990 building stock, ultimately fostering more sustainable educational environments across Romania.