Developing an environmentally friendly and sustainable building is an interdisciplinary task. Only by working with a team of people from different building disciplines is it possible to solve the problems that occur in the integral planning process. The Center for Sustainable Building (ZUB) is an example of a successful planning process and represents today's state of the art in low energy and sustainable office building in Germany. The new office was planned as a demonstration project for low energy building. The new office contains about 1300 m2 of floor space and is attached to an existing building from the early 20th century. The building consists of three different main parts: a lecture hall for exhibitions and events, offices, and laboratories for research on innovative building technologies and components. Sustainable building materials were used in the construction. The building was funded by the Bundesland Hessen. To increase energy efficiency and solar energy use, the Federal Ministry of Economy and Technology provided co-funding for the innovative technical systems and the research and monitoring project. During two and a half year long monitoring period, around 1300 data points were recorded and evaluated. On the basis of these measurements, the targets of the research program were exceeded and the technical systems were optimized to their full potential. Results and findings from the monitoring process are presented in this article. The comparison with results from a building simulation offers an opportunity to abtain actual proof, to quantify the achievements of a sustainable building, and to demonstrate current possibilities of energy conservation design.