Improving Energy Efficiency of School Buildings: A Case Study of Thermal Insulation and Window Replacement Using Cost-Benefit Analysis and Energy Simulations

This study demonstrates the benefits of comprehensive school building (SB) energy efficiency (EE) improvements through building envelope renovations, lighting upgrades, and changes to cleaner heat sources. The parametric study in the building energy simulation software was used to check the application of various interventions on the energy consumption of existing SBs while reducing CO2 emissions with the most profitable return on investment (ROI). The energy savings from window replacements did not correspond with expectations. However, other measures such as the wall, roof insulation, and lighting modernization improved EE by up to 152 kWh/m2 and 41 kg/m2 CO2/m2 annually. The study also points to a significant trade-off between district heating (which reduces CO2 but has a slower ROI) and other heating solutions. The results suggest that climate-specific insulation thickness and glazing type needs are required, and optimal insulation strategies are shown to improve EE by 48–56% and CO2 reductions of 45–56%. Lighting replacement and biogas boiler use were both impactful. The findings support the importance of sustainable practices, which should stimulate educational awareness and environmental responsibility. This research presents actionable insights for EE and sustainable development from within educational facilities.