The work on the Austrian voluntary green building assessment scheme called TQB (Total Quality Building) started at the end of the 1990ies, responding to a serious problem: Quite often, building designs optimised in terms of sustainability including energy efficiency and renewable energy use were not realised as planned but with lower quality, because of various reasons, such as lack of quality of the works, the intention to save investment cost, or faulty interfaces between staff involved in planning and staff involved in execution. In the end, the quality defined by means of certain indicators on paper did actually not correspond with the as-built situation. However, regarding reductions of energy consumption and emissions only the actually achieved status is relevant. For this reason, a two-step assessment approach was chosen from the beginning: first, assessment of the building design, and second, assessment of the completed building. Among others, the assessment requires the EPC as a supporting document. This factsheet presents the Austrian voluntary green building assessment scheme, how it is applied to facilitate smart city developments, and also explains how QUALICHeCK project results are being used to improve the system and the procedures.