The SAVE research project takes circular building technology to a new level – by separating urine directly in the building. This saves resources, relieves the burden on sewage treatment plants and produces local fertilizer for green facades and roofs. A pilot project in the “Village im Dritten” shows how wastewater can be turned into ecological responsibility and smart urban development.

Text Dipl.-Ing. Susanne Formanek, GRÃœNSTATTGRAU Forschungs- und Innovations GmbH

—

Modern bathroom with pink floor and pink wall. On the left is a wall-hung white toilet, next to it a white bathtub. In front of it is a small, transparent glass table in green. Bright, minimalist design.Run save! (c) Run

Resource-saving nutrient recovery in buildings: the SAVE research project as a pioneer of circular building technology concepts

Urine contains high concentrations of nitrogen and phosphorus – two key elements for fertilizer production. If this valuable raw material is separated and processed directly at source, this opens up new perspectives for sustainable building technology and resource management in urban areas. This is precisely where the SAVE – circular approaches for green buildings! research project comes in.


Problem: Excess nutrients pollute water bodies
Conventional wastewater treatment plants remove less than 80 % of nitrogen from wastewater on average. The remainder ends up in rivers, lakes and ultimately the sea via receiving waters – together with nutrient inputs from agriculture. The result is eutrophication and oxygen deficiency zones in which biodiversity is lost. The targeted removal of these substances directly at the point of origin would therefore make sense both ecologically and in terms of building technology.

Technological approach: urine separation with teapot principle

The Viennese design studio EOOS NEXT, known for its socially and ecologically oriented industrial design, has developed a new type of urine-diverting toilet called “save!” together with the sanitaryware manufacturer Laufen. The system uses a physical principle that is familiar from everyday life: like a poorly constructed teapot, liquid runs off the outside as it moves slowly. This behavior is specifically used in the “save!” toilet to direct urine into a separate “urine trap” without mechanical components. There it is collected via a separate pipe system and temporarily stored on site.

Fig. visualization BTW Village in the third, expressiv/Gerner Gerner plus and heri&salli

Research partnership and pilot project in residential construction
The SAVE project, funded by the BMIMI and FFG, was launched in 2022. In addition to EOOS NEXT and Laufen, the property developer ARWAG, the Institute of Building Research & Innovation and the GRÃœNSTATTGRAU platform are also involved. The focus is on integrating the technology into a real new-build project: the “Village im Dritten – Das Stadtregal”, a residential building with around 120 units. Here, 36 apartments are being fitted with “save!” toilets for the first time.

The research project pursues a circular overall concept: the collected urine is converted locally into fertilizer and used to green the building at the same location. This combination of sanitary resource recovery and green-blue infrastructure promotes microclimate improvement and evaporative cooling in the neighborhood.

Technical and building physics potentials:

  • For every 100 users, around 400 kg of nitrogen and 40 kg of phosphorus can be recovered annually – enough to fertilize around 4 hectares of farmland.
  • Local recycling reduces greenhouse gas emissions, saves natural gas (nitrogen synthesis) and avoids environmentally intensive open-cast phosphate mining.
  • In combination with extensive or intensive façade and roof greening, heat loads can be reduced, evaporation performance increased and rainwater peaks buffered.
  • Reducing the urine content in wastewater relieves the sewer system and simplifies the biological removal of nutrients in wastewater treatment plants.

The combination of water and nutrient cycles with thermally effective greening strategies creates a high degree of resource efficiency. At the same time, system integration allows new evaluation approaches in terms of life cycle engineering, both in economic and ecological terms.

The SAVE project exemplifies the potential of circular building concepts: it combines technical innovation, building physics effectiveness and ecological responsibility. The use of urine as a resource creates a new quality of sustainability in urban construction – integrative, measurable and circular.

Further information: SAVE circular approaches for green buildings! – GRÃœNSTATTGRAU (gruenstattgrau.at)