Energy efficiency, sustainability of interventions and efficient management of the conservation process are three increasingly important features of the restoration and regeneration of urban historic fabrics. Several studies identify in the Heritage-BIM the most suitable instrument for the integration and management of knowledge produced during the conservation process, with ongoing experiments that, from the field of representation and geometric survey, have gone in the direction of a multidisciplinary approach. Numerical simulations are one of the most powerful tools for improving energy efficiency of the built heritage, not only for the understanding of complex phenomena and the analysis of the energy and environmental consequences of conservation interventions (also in terms of deterioration), but also because they allow innovative applications in the field of non-destructive analysis and in the reconstruction of the original passive behaviour of historic structures. An HBIM model already contains much of the information required for numerical analysis of historical structures, and interoperability can save time by reducing errors in manual steps but at the moment the process of integration between the two software environments is still complex and in an embryonic phase that requires a multidisciplinary approach and the involvement of numerous experts from different scientific fields. The article describes the methodology of integration between multidisciplinary analyses, HBIM modelling and simulation analysis adopted within the METRICS research project, where it was possible to test the limits and potentials of the currently available approaches, exploiting the digital medium of computational design to bridge the gap between BIM and simulation environments.