Economic and Energy Efficiency of Building Modernizations

This contribution assesses the economic and environmental performance of energy-efficiency upgrades in existing buildings, focusing on thermal envelope modernization. Drawing on data from 140 retrofit measures across 57 buildings, it compares lifecycle costs and energy savings under varied component conditions. Results show that exterior wall insulation delivers the highest return on investment, followed by roof insulation and window replacements, while skylight upgrades are least cost-effective. The analyzed measures could save over 250 million kWh and prevent 80,000 tonnes of CO₂. The study introduces an evidence-based framework for prioritizing retrofit investments and guiding strategic funding for building decarbonization.