Balancing preservation and utilization: Window retrofit strategy for energy efficiency in historic modern building

In modern historic buildings, the decline in energy efficiency due to aging necessitates both the preservation of historical value and the need for energy retrofits. However, the windows cannot be altered due to the historical significance of the building's windows in terms of design and materials. Retrofitting windows in modern historic buildings require a more multifaceted improvement than other envelopes. This research examines the energy efficiency of a retrofit strategy that adds double-glazed windows to existing exterior windows. Through the application of retrofit technology, the performance of the windows and their impact on indoor temperature and relative humidity were analyzed. The research conducted an energy performance analysis using building energy simulations to assess energy savings. To ensure accurate energy efficiency evaluation, on-site indoor temperature and relative humidity monitoring, as well as non-destructive thermal performance assessments, were performed. The results revealed a 35 % improvement in airtightness with window retrofit. Based on these results, simulation results showed a 17 % reduction in annual cooling energy consumption and a 24 % reduction in annual heating energy consumption following the implementation of retrofit strategies. Thermal performance improvements proved effective in reducing cooling energy consumption, while airtightness improvements were more effective for heating energy consumption reduction. Consequently, for buildings requiring both heating and cooling, the double-glazed windows retrofit strategy emerged as an energy effective retrofit approach capable of enhancing both airtightness and thermal performance. This retrofit will unlock new possibilities for the preservation and revitalization of modern historic buildings, allowing them to continue their legacy.