Oneplanetarchitecture is the design philosophy Thomas Rau, the founder and director of RAU, developed over the recent years. It implies a broad approach towards the building task taking into account the material and immaterial needs of users, the place, the society, and the planet earth. Therefore the process as such is a central part in the work of RAU which always results in a unique concept which is imbedded into the building's social and urban context. The work of RAU seems to pursue a variety of directions. RAU considers that the appearance of their buildings has less to do with style than with methodology. The firm's buildings have to be different because each is designed according to particular circumstances, such as the history of the place, the needs of the user, the local context, and the social value. Rau and his team search for what they call the DNA of the building that is the underlying factors that seem to require or predetermine its form, for the design process as they see it ideally should not be an imposition of preconceived ideas, but a metamorphosis through multiple versions until the most appropriate combination of qualities is discovered ...Thomas Rau stresses that it is not so much individual energy saving measures that are important as their integration in a total design. An exemplary client was the Triodos Bank, for which RAU built both the Dutch headquarters and more recently the headquarters for the International branch. In a way typical of RAU, it combines concerns for the site, for accommodating and expressing the nature of the firm, and for setting a serious green agenda as an example of the bank's green attitudes visibly put into practice. The complexity of this approach to architecture is explored through a series of essays from different points of view, complemented by a glossary of measures for sustainable building integrated in RAU's designs. This is followed by an in-depth documentation of over forty projects designed by the firm.