The "circle house" (german: Kreis-Haus) initiated and designed by the Zurich University of Applied Sciences (ZHAW) is built entirely in the spirit of the circular economy. "We have tried to implement the principle down to the last detail and in the smallest possible space," says environmental scientist Devi Bühler.

The idea of the circular economy already started with the excavation: the nutrient-rich soil was not dumped, but used for the roof garden and integrated into the surroundings of the house.

The small building stands on a concrete-free foundation, which is intended to have less impact on the soil. The windows on the south side of the house, built of clay, lime and wood, come from a demolition site and the floor is made of recycled glass fragments.

Waste water is treated

Not only building, but also living in the "Kreis-Haus" should be sustainable: Collected rainwater is processed into drinking water. Electricity comes from the sun, and heat reaches the living space via a ventilation system from the house's own conservatory.

In addition, slightly polluted wastewater from the kitchen and bathroom is treated directly and used for irrigation, nutrients are recovered from urine as fertiliser for the roof garden, and faeces end up in a container where worms do their work.

Trying out new technologies

The house is used by the researchers to try out new circular technologies and materials in practice.