Abstract: Buildings have a large impact on the environment, economy and society: they consume 40% of the energy, produce 30% of the green house gas emissions, generate 25% of the solid waste, use 25% of the potable water, dissipate 12% of the land use, spend up to 40% of the countries´ gross domestic product [1]. Furthermore people spend about 90% of their time in buildings, what makes it important to provide them a healthy and comfortable indoor environment. For the management and implementation of all these aspects a lot of tools have been developed. Important examples are methods of the first generation like the "British Research Establishments Environmental Assessment Method" (BREEAM) [2] in 1990 or the American label "Leadership in Energy and Environmental Design" (LEED) [3] in 1996, as well as methods of the second generation, like the DGNB Certificate [4] 2009. These concepts differ from each other and nowadays worldwide, as well as in Europe, there is still no common understanding of the concept of sustainable building. With projects like OPEN HOUSE [5] , SuPerBuildings [6] – both promoted by the European Commission – or the standards from ISO TC 59/SC 17 as well as CEN/TC 350 a process has been initialized to harmonise all these approaches. This paper will give a worldwide overview how sustainable buildings are currently assessed. As well as an insight in the development of the OPEN HOUSE methodology with the actual model, upcoming case studies and implementation in the building market. [1] United Nations Environment Programme: Common Carbon Metric. http://www.unep.org/sbci/pdfs/Common-Carbon-Metric-for_Pilot_Testing_220410.pdf. (07.11.2010) [2] http://www.breeam.org/ (30.9.2011) [3] www.usgbc.org/LEED/ (30.9.2011) [4] http://www.dgnb.de/ (30.9.2011) [5] http://www.openhouse-fp7.eu/ (30.9.2011) [6] http://cic.vtt.fi/superbuildings/ (30.9.2011)