The sustainability of buildings has moved more into the focus over the past few years, and certification systems for sustainable buildings and the development of new criteria and assessment systems are being given more attention. The Working Group on Sustainable Construction deals intensively with the assessment and certification of sustainable buildings. Through cooperation in various expert groups, it is working on further developing the building certification system of the German Sustainable Building Council and deals with the ongoing development of criteria and benchmarks. The theoretical knowledge is put to use in various national and international research projects, and in industrial schemes. New criteria and strategies in the field of building sustainably are developed as required in specific projects and situations. Individual circumstances and regional framework conditions are thereby given due attention. Optimization potential is tapped in the different building phases, and recommendations for action derived. When timely attention is given to sustainability objectives in the planning phase, these can be achieved economically and efficiently.