## 1 Introduction
The testing of new ecological building materials and components must be accompanied by innovative technologies to guarantee energy efficiency in the early project phase [12]. The design of high-energy performance buildings requires the creation of a shareable working environment, where architectonic and energy solutions can communicate easily and exchange all of the required information. During the last two decades, BIM has been established as a tool with the potential to significantly transform the building industry [13]. With the increasing complexity of buildings, the control of building projects has also become more challenging [14]. In this context, BIM, as a multi-functional method, can support the whole building design process and contribute to constructing ecological buildings [15]. Its power resides in the very exact and detailed digital reproduction of all architectonic building elements. Such working practice brings benefits not only for the environment but also for the future users of the buildings because the possible energy savings cause a distinctive reduction in operation costs. At the virtual conference, Sustainable Places 2020, nine EU-supported research teams presented their results and innovations; all of those projects had their attention set on recent challenges related to the digital transformation in civil engineering [16]. Moreover,the building sector was evaluated as the least productive sector in Europe because of the difficulties with implementing digital innovations [17]. The principal aim of BIM, as an integral part of the building sector, is to improve the cooperation between various interested parties [18; 19] and to increase the efficiency at the building sites and between various project phases [20]. BIM, as the key tool in cyber-physical systems, also improves the quality of the building objects during their whole life cycles, in accordance with the paradigm Industry 4.0. It can be taken as the necessary means for the interconnection of digital technologies with the building industry [21]. Its tools for the management of digital information make it possible to optimise and control the complete building process [22]. BEM, together with the BIM conception, then forms the basis for the certification of energy performance (EPC) of buildings. Such certifications must be user-friendly, reliable, and profitable from the economic perspective, for them to obtain the investors' confidence [22]. Three categories of BEM can be distinguished: (i) the physically based (white box) ones [23], (ii) the purely data-driven (black box) ones [23], and (iii) the hybrid (grey box) ones [24]. Interoperability between BIM and BEM is the key step for decreasing costs and reducing the time needed to create models in the design phase. The potential of BIM is in making this creation more effective, thanks to the stored important data, such as building geometry, structure typology, and physical properties [25]. Iterative development of effective proposals in a shared environment is supported [26]. BEM tools are useful for understanding different ways to reduce energy consumption [27], thanks to computational energy simulations, analysis of real energy demands, and multi-criteria optimisation of project design [28]. Apart from evaluating BIM as a multi-disciplinary tool [29], the interoperability between BIM and BEM still contains unpleasant digital problems. The rather weak compatibility between BIM models and applications for energy simulations, repeated manual operations, and non-standardised processes result in data loss and incorrect interpretations, as identified by [PERSON] et al. [30]. Such difficulties force frequent substantial revision of the model, which is unnecessary additional work for the designer. Following these findings, [PERSON] and [PERSON] [31] focused on developing standards needed for the above-mentioned interoperability. Multiple file formats are currently used for data transfers from BIM to BEM, e.g., HTML, XHTML, bcXML, IFCXML, IFC, and gbXML.