Terms such as sustainability, climate change or green buildings belong in the meantime no longer to the exotic foreign words, they became rather common. The focus of the building and real estate economy is in change, which is subject not only to the time, but above all the circumstances. Buildings and urban areas are today differently planned, realized and operated already, than they became it in the past. The climate, its impacts, humans and the real estate stand thus in faster interdependency to each other and cause themselves increasingly mutually. Green or sustainable buildings are buildings designed and built environmentally responsible and resource-efficient throughout a building's life-cycle. The definition of a green building and especially a sustainable building is, as the range of worldwide rating tools to measure sustainability, huge. Furthermore the authors see a significant difference between green and sustainable buildings.