Interoperability Challenges in BIM-to-BEM Workflows for Sustainable Building Assessment: A Comparative Study of Native and Middleware-Based gbXML Export

Reliable integration of Building Information Modeling (BIM) and Building Energy Modeling (BEM) is essential to sustainable design and renovation because energy-efficiency decisions depend on consistent analytical models. However, native gbXML exports often contain geometric and semantic inconsistencies that can distort energy assessments. This study evaluates native export limitations and the effect of middleware-based transformation on BIM-to-BEM interoperability. A residential building was modelled in Autodesk Revit and Graphisoft Archicad. gbXML exports and the BIMTWIN workflow were assessed using geometry, analytical integrity, and heat-loss indicators; only geometric results were compared with the Energy Performance Certificate. Although all workflows generated gbXML files, their analytical quality differed substantially. The middleware-transformed model deviated by only +1.53% and +2.25% from the reference external and internal volumes, respectively. Native Revit export omitted intermediate floor constructions and produced a total heat loss of 95,785 W, 25.2% higher than the 76,533 W obtained from the transformed model. Native Archicad export produced fragmented geometry unsuitable for reliable heat-loss calculation. The results show that BIM-to-BEM interoperability should be treated as a controlled validation and transformation process. By reducing analytical errors and manual reconstruction, this approach supports more reliable assessment of energy-efficiency measures and better-informed decisions in sustainable building design and renovation.