Prof. Suncica Milosevic and Prof. Ajla Aksamija presented a research paper at the STRAND OA2025 13th International Conference and Exhibition, organized by the Sustainable Urban Society Association and hosted by the the Serbian Academy of Sciences and Arts and Gallery of Science and Technology in Belgrade, December 4 to 5, 2025. The study presented energy-efficient retrofit strategies for a culturally significant building, the Sava Center, located in Belgrade. The Sava Center is one of the most iconic architectural and cultural landmarks, built between 1976 and 1979. It functioned as a major congress and cultural venue, embodying ideals of civic ambition, technological innovation, and public accessibility. The study presents a performance-based retrofit framework for historically significant buildings of this scale and typology, bridging architectural history, building science, and digital performance modeling. Research methods included archival research, BIM modeling, hygrothermal and thermal envelope simulations, and whole-building energy analysis. Results suggest that the retrofit design strategies could significantly reduce energy use while preserving the building’s original character, programmatic intent, and civic function. The presentation also offered insights into policy gaps and recommendations for energy-efficient retrofits of culturally and historically significant buildings.