The premises in Düsseldorf are used as office space, co-working space and showroom for circular interior design. The entire interior consists of healthy materials that are either biodegradable or upcyclable. Alternatively, second-hand materials are used. Ecological clay building materials from ClayTec were also used in the renovation, which can also be assigned to the Cradle to Cradle circular economy principle. Clay can be reused as often as required or, alternatively, can simply be returned to nature. The use of sustainable clay building materials therefore supports the goal of “building without waste”. The wood fiberboard (HFA) N+F D20, as well as the clay filler and surface filler, were used for the ceilings of the Düsseldorf office. In addition, a telephone booth was created within the office, which is used as a retreat for telephone calls and video calls. ClayTec HFD interior insulation boards were used to build the telephone booth. These serve as acoustic insulation between cellulose panels and panels made of seagrass. The HFD interior insulation board has remained visible on the ceiling of the telephone booth. Functionality, design and the use of sustainable materials were successfully combined in the design of the offices, demonstrating how fully circular construction is already possible today.