Building Information Modeling (BIM) and Building Energy Modeling (BEM) can revolutionize the building design process, enabling early-stage energy analysis and sustainable design. However, effective interoperability between these tools remains a significant challenge. This paper investigates two strategies for bridging the gap between BIM and BEM: real-time connection (S1) and standardized exchange formats (S2). A case study building was employed to compare the performance of these approaches, and all dynamic energy simulation models were calibrated using statistical analysis of experimental thermal energy consumption data. While S1 proved to be limited by customization constraints and consequently not applicable for the case study selected, S2 demonstrated successful interoperability, yielding energy-calibrated model results consistent with traditional BEM methods, with a difference of only 2 % in annual thermal energy consumption obtained. This work, concretely testing the BIM-to-BEM approach, is able to suggest practical actions to improve communication between software where possible. Furthermore, the direct comparison between the different approaches to modeling allows to clearly highlight the advantages and disadvantages of each one, underlining the importance of reliable data exchange for accurate energy simulations and the need for further advancements in BIM-to-BEM interoperability to fully realize the benefits of integrated design.