Rethinking level of detail (LoD) for BIM-BEM workflows: Geometry, envelope and HVAC effects on interoperability and energy simulation

Building Information Modeling (BIM) and Building Energy Modeling (BEM) interoperability plays a key role in the digital transformation of the construction industry, as it enables the integration of energy performance analyses from the early design phases. However, despite its significant potential, BIM–BEM workflows are still hindered by inconsistencies across software tools, data exchange formats, and modeling approaches. This study explores the influence of different Levels of Detail (LoD) in BIM models on the reliability of data transfer from BIM to BEM and on the accuracy of subsequent energy simulations, with particular attention to standardized formats such as gbXML. An academic building with complex geometry is used as a case study, and several export scenarios are evaluated using Autodesk Revit and DesignBuilder. The findings reveal that highly detailed geometries are often incorrectly interpreted within BEM environments, while envelope thermal properties tend to be consistently and accurately transferred across all LoD levels. In contrast, information related to Heating, Ventilation and Air Conditioning (HVAC) systems shows significant interoperability challenges and often needs to be manually redefined within the energy modeling software. Furthermore, HVAC system representation emerges as the primary source of uncertainty in simulation results. Simplified HVAC models lead to substantial overestimations of thermal energy consumption, ranging from 36% to 59% compared to measured data. Overall, the results support a “just enough detail” modeling approach, empha-sizing the need to carefully select appropriate LoD levels in order to achieve consistent, reliable, and realistic energy performance predictions.