MOEEBIUS introduces a Holistic Energy Performance Optimization Framework that enhances current (passive and active building elements) modelling approaches and delivers innovative simulation tools which (i) deeply grasp and describe real-life building operation complexities in accurate simulation predictions that significantly reduce the “performance gap” and, (ii) enhance multi-fold, continuous optimization of building energy performance as a means to further mitigate and reduce the identified “performance gap” in real-time or through retrofitting. The MOEEBIUS Framework comprises the configuration and integration of an innovative suite of end-user tools and applications enabling (i) Improved Building Energy Performance Assessment on the basis of enhanced BEPS models that allow for more accurate representation of the real-life complexities of the building, (ii) Precise allocation of detailed performance contributions of critical building components, for directly assessing actual performance against predicted values and easily identifying performance deviations and further optimization needs, (iii) Real-time building performance optimization (during the operation and maintenance phase) including advanced simulation-based control and real-time self-diagnosis features, (iv) Optimized retrofitting decision making on the basis of improved and accurate LCA/ LCC-based performance predictions, and (v) Real-time peak-load management optimization at the district level. Through the provision of a robust technological framework MOEEBIUS will enable the creation of attractive business opportunities for the MOEEBIUS end-users (ESCOs, Aggregators, Maintenance Companies and Facility Managers) in evolving and highly competitive energy services markets. The MOEEBIUS framework will be validated in 3 large-scale pilot sites, located in Portugal, UK and Serbia, incorporating diverse building typologies, heterogeneous energy systems and spanning diverse climatic conditions.