There is a nameable number of stakehoders involved in planning, constructing and operating buildings. Moreover the participants in the stakeholders' group vary from one project to another. Each one of these stakeholders is - more or less - capable of taking influence in the implementation of sustainable strategies that are composed of economical, ecological and social aspects. The question arises, who the key actorsconcerning sustainability are and therefore determine the impact on the environment, the economy and the society. Key actors are identified by analyzing their personal aims, their roles within the actors' network and their involvement in significant decisions. Their decisions frame the overall picture of the actors' groups and their impact on the building and its quality of sustainability. A strong factor in the decision making process is the application of certain technics and conventional methods that often don't allow to install specific parameters dealing with sustainability matters. Furthermore interviews with representatives of actors' associations have shown that certain technics either lack the opportunity of taking sustainability parameters into account or are not applied correctly (i.e. in a simplified way) at all. This paper gives a close insight into the structure of people working in the real estate business and the buiding industry and their boundaries and potentials to develop sustainable houses in Germany.