Different users and investors´ project preferences, often lead to trade-offs during the early design phase of a project. Currently, decisions of design options and their technical measures are mainly reduced to an instantaneously assessed criterion (i.e. energy efficiency) within the sustainability assessment of buildings. Due to criteria interdependency, the current linear applied approach used in building certification neglects criteria trade-offs and is therefore only partly suitable for holistic building improvement processes. In order to fulfil stakeholder interests on the one hand and a high sustainability performance on the other, it is crucial to identify appropriate design measures. Based on the Austrian building certification system ÖGNI/DGNB, we applied a systemic approach for building sustainability-improvement, using a case study of a public office building in Graz, Austria. The main part of the study describes the important steps required for the systemic optimization of building sustainability. The method applied in this study allows the quantification of the relative influence and the identification of the individual optimization potential of design options on each single assessment criterion. The proposed systemic approach clearly demonstrated the improvement potential of the currently most developed building certification system considering the interdependency between the individual criteria.