A greywater recycling system combined with heat recovery from greywater was launched in March 2012 in a multi-storey passive house in Berlin, Germany and is running since then problem-free and at very low maintenance. Greywater from showers and bathtubs undergoes an advanced physical-biological treatment followed by UV disinfection without the use of chemicals. For a standard passive house, which has a heat demand for space heating of less than 15 kWh/m2/a, more energy is needed for hot water generation than for space heating. A total of 41 flats with 123 tenants occupying an area of 4,600 m² and 4 commercial units (600 m²) are connected to the greywater/heat recovery system. About 3,000 litres of low load greywater are treated daily to produce high quality service water which is reused for toilet flushing. The filtered greywater enters the heat exchanger, where heat is withdrawn by a 20-watt circulating pump before it undergoes biological treatment in a Moving Bed Biofilm Reactor (MBBR) followed by UV disinfection. CONCLUSIONS - Greywater is a renewable and safe resource for non potable water and energy. - Higher water and energy savings as shown in this project are possible. - Total system costs including dual pipe network are less than 0.6% of the total apartment costs. - More than a tenfold higher water and energy efficiency, compared to central systems, can be achieved with a decentralised approach by operating greywater recycling plants in combination with heat recovery. - Today no new building should be designed without a dual pipe network for water and energy recycling!!

Bibliographic information

Nolde, E. (2013). Water and energy recycling at a residential passive house Poster at the Sustainable Building Conference in Graz, Austria, Nolde & Partner Innovative Water Concepts, Berlin, Germany

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OtherGreywater or wastewaterUrban (entire city)Posters, brochures and flyersEnglish

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