The building for the United Nations Environmental Council has an exemplary role, has to be recognizable, easily accessible, facilitate lobby, stimulate people to participate and above all radiate to the world the importance of sustainability. Since sustainability can not be confined and even more so the future interpretation of sustainability is entirely unknown, this design proposal focuses on the integration of environmental resources in the architectural appearance of the building. This will always be relevant as well that it increases the observers awareness and will lead to a gradual change of attitude with regard sustainability. An environmental approach has a significant effect of the aesthetics and functionality of the building. The building is optimized towards the sun positions in summer and winter, the prevalent wind directions in winter and summer, daylighting conditions and natural ventilation. Furthermore the building employs environmental resources (passively and actively), using wind turbines, algae cultivation, thermal solar panels, hydro storage, PV cells, river heat rejection and solar chimneys, which all have a determining effect on the appearance of the building. The extraordinary interior derives from the four themed towers (wind, algae, solar, hydro). Due to the slender tower, and small footprint, vertical chained spaces emerge, making use of the concept of the spiral: Vertical auditoria, vertical library and vertical offices, all are chained belong to the same space using spiraling ramps. The outline of the towers is visible in all interior spaces, occupying a significant factor is the atmosphere in the towers, making one feel the part of the tower. In the public hall, the encounters between various user groups occur. Spaces for short stay are created to stimulate encounters and lobby. With the coulisse-effect of the column one can withdraw oneself from the openness of the hall to a more secluded space, while still be part of the hall full of activities. The natural obstacle of height is used to separate several occupancy paces of various user groups. This allows for a very transparent organization, and signifies the accessibility. The construction of the hall, (north truss and roof beams are determinant) for the atmosphere in the hall. The rotation of the roof beam derives from the tower shape. The presence of the towers and the significance these bear can be felt throughout the whole interior, but also at the exterior of the building.