As part of his master’s project at ETH Zurich, Leon Adamski examines how the HIL building on the Hönggerberg campus can significantly reduce its water consumption and close material cycles. With a capacity of around 1,600 occupants and an annual water consumption of approximately 10,000 m³, the building is among the most resource-intensive on campus. Accordingly, it offers considerable potential for sustainable optimisation.
The project analyses current water consumption and develops an integrated concept with three objectives: reducing drinking-water demand, decreasing the volume of wastewater, and lowering the nutrient load entering the local wastewater system. Based on building data, literature values and a systematic technology assessment, the study proposes a package of measures that combines several approaches.
The recommended concept includes water-efficient fixtures, the use of rainwater for toilet flushing and irrigation, and complete urine separation. The collected urine is treated off-site using a nitrification–distillation process and converted into a high-quality fertiliser. The remaining wastewater stream is pre-treated within the building using vermifiltration, a nature-based filtration process.
Overall, the concept could reduce the HIL building’s drinking-water demand by around 75%, its wastewater volume by 42%, and nutrient loads entering the campus wastewater system by up to 78%. The study shows that building-scale water cycles are technically feasible and offer considerable potential for developing the HIL into a living lab for sustainable building technology.
Decentralised water supply and wastewater treatment systems are often used in locations where central infrastructure is unavailable or has reached its limits. Increasingly, however, such technologies are also being implemented in urban buildings to reduce resource consumption and ease the burden on existing infrastructure.