Integrating EPC Data into openBIM Workflows: A Methodological Approach for the Digital Building Logbook

European strategies are increasingly pushing for the optimisation of building energy performance, a goal that demands structured, in-depth knowledge of existing built heritage. In this scenario, digitalisation emerges as a key enabler, offering the opportunity to consolidate critical building lifecycle information through the progressive development of a Digital Building Logbook. Central to this process are openBIM models, which go beyond traditional geometric representations by introducing a semantic framework that integrates 3D geometry, spatial relationships and descriptive data, making the logic of the asset visible and queryable. This study presents a systematic methodology to link data from Energy Performance Certificates, structured in eXtensible Markup Language, with the Industry Foundation Classes standard. The proposed workflow includes a detailed analysis of data formats, classification of energy-related information and the mapping of correlations, whether through existing standards or custom Property Sets. The methodology is validated through an Italian case study, with data integration tested via visual programming. Looking ahead, the workflow will be automated to support the development of a visualiser capable of integrating both energy and Building Information Model domains. In doing so, representation evolves from a static tool into a dynamic interface for managing and analysing information, expanding the potential of digital drawing to describe, interrogate and simulate the energy behaviour of the built environment.