The advance of Building Information Modelling (BIM) in recent years expedited its use in a growing number of AEC projects and practical tasks. Along with that, various problems that had been addressed earlier in narrower scope had to be reconsidered in search for adequate industry relevant solutions. Such problems include collaborative work support, change and version management, life cycle sustainability and so on (Eastman et al. 2011). Continuously extending the use of BIM-based working and the related interoperability needs of more and more specialised AEC tools in various construction subdomains showed also that a global all-encompassing model for all data in a construction project is neither realistic nor practical target, and that BIM data typically have to be combined with other kinds of construction related data to be efficiently applied in real practical tasks (Scherer & Schapke, 2011; Arayici et al. 2011). Thus, while the current standard BIM specification IFC (ISO 16739, 2005) has been successfully extended to support various domain-specific processes (https://www.buildingsmart-tech.org) and

several RTD projects such as STAND-INN and InPro (https://www.aec3.com/en/5/index5.htm) have shown how domain application interoperability can be achieved by suitably extending BIM-CAD data, the problem how non-BIM data or BIM-related non-AEC data from external resources can be best integrated is still relevant for many practical situations. Furthermore, the quality of the actual BIM data and the prerequisites a model should fulfil to efficiently support information interoperability in a specific target domain are issues that should not be underestimated as potential sources of error or considerable time loss. This paper examines the possible use of IFC as information basis for energy-efficient building design and operation discussing in particular the challenges to data modelling in the domain, an approach to meet these challenges developed in the frames of the EU project HESMOS (Liebich et al. 2011, Baumgärtel et al. 2013) and practical experiences gained from two real projects using the HESMOS approach.The energy domain is of special interest here because of its pronounced interdisciplinary nature and the high societal pressure in “green” construction, witnessed e.g. by the McGraw Hill Construction Global Report 2013, which

states that by 2015 over 60% of all construction work worldwide is going to be sustainable construction or green construction (McGraw Hill, 2013).