Forum Chriesbach

In order to meet the growing demand for extra space, Eawag and Empa jointly constructed Forum Chriesbach in Dübendorf. The members of the Eco Team were consulted from the outset, when the project specification was formulated. Issues of sustainable development were given high priority right from the start. The stipulations were to achieve as high a degree as possible of self-sufficiency in terms of energy supply from renewable energy sources, an exemplary and efficient use of water (including the separation of urine), and the use of environmentally friendly materials and landscaping that provides a beneficial environment for flora and fauna as well as people. Forum Chriesbach became operational in July 2006, since which time it has been the headquarters of Eawag.

The Forum Chriesbach is located on the Campus Empa Eawag site in Dübendorf. The office and research building, which also houses the library, training rooms and the staff canteen, has set new standards in sustainable development. When planning the building, the construction techniques and technology employed pushed the then available systems to their limits. For example, the building uses four times less energy than a conventional building; the office areas are neither heated nor cooled by conventional systems. And the installation of a sophisticated sanitation system - NoMix toilets which separate urine, rainwater used for flushing toilets - means that the latest research results of Eawag are tested in everyday situations. Almost 2000 visitors from Switzerland and abroad come to view the building each year and it has been the subject of numerous media reports and publications.


The building is a compact entity with a large glass-roofed atrium which allows daylight and - a welcome feature in winter - the heat from the sun to enter the building. The reinforced steel frame construction acts as a heat and cold storage unit, while the interior clay and gypsum walls in the offices regulate air humidity. The escape balconies are accessible from every room and are fitted with the striking blue glass panels which turn to follow the sun and provide shade or let in the sun according to the season. The rooms are distributed in a U shape around the 5-storey atrium which offers a true spatial experience with its suspended meeting cubicles and the open staircase. The reception and exhibition area in the atrium can also be used for major events. A model of the water molecule with an image projection system is the eye-catching feature in the entrance area.

The space allocation plan comprises 165 office workstations, a lecture hall for 80-140 persons, 2 seminar rooms for 30-40 persons each, seven meeting rooms for a total of 110 persons, contact areas on four floors with desks and seating areas, the library shared by Eawag and Empa, the aQa staff canteen as well as adjoining rooms and technical service areas.


General contractor

Construction data

Volume (SIA 116) 38615  m³
Floor area FA (SIA 416)  8533  m²
Roof area (building footprint) 1886  m²
Energy reference area ERA 11170  m²
Energy reference area ERA (uncorrected) 8270  m²
Capacity of hot water tank 12  m³
Capacity of reservoir in the water garden 80  m³
Building cost classification (BCC 1-8) 29’700  k SFr
Solar panel system incl. converter, etc. 888  k SFr
Vacuum tube collector system incl. pipes 136  k SFr
Additional costs compared to a standard building 1'400  k SFr (4.7% of construction costs)
Offices 150  workstations
Lecture hall 140  seats
Seminar and meeting rooms 180  seats
Staff canteen 150  seats
Standard capacity 220  persons


With the exception of the ground floor (staff canteen, library, reception) the Forum Chriesbach is not heated. The warmth generated by people, work aids, lighting and solar radiation is sufficient to maintain a pleasant ambient temperature. The roof, floors and façades have excellent insulation; air is renewed continuously and controlled from a central unit. The temperature and air quality are only monitored in the comfort zone (work and conference rooms), but not in the atrium. Hence the optimum room climate is achieved when the doors are kept closed.

In winter the fresh air intake is preheated in the thermal register and warmed up again by the waste heat from the computer servers. In addition, the heat recovered from exhaust air is also utilised via heat exchangers. Where necessary, it is possible to heat up the intake air using the hot water tank. This tank is heated by solar panels, the waste heat from the refrigerators in the kitchen and (where necessary) from the heating network on the Campus Empa Eawag site.

In summer the intake air is cooled by the thermal register and distributed to the rooms. On hot days the building is cooled at night via the window casements which open automatically. The warm air escapes through the atrium roof and cool air flows into the rooms. The photovoltaic installation on the roof provides c. 100 MWh of electricity per annum, around one third of the operating energy (without servers) for the Forum Chriesbach. The solar thermal installation produces around the same amount of energy as is consumed via the site heating network, i.e. around 24-26 MWh per annum.

The detailed energy balance of Eawag's Forum Chriesbach has been investigated and documented in a scientific study.

  Planning Values '07
Heating demand Qh (standard utilisation SIA) 14  kWh / m² BEI a 24  kWh / m² BEI a
Thermal consumption from Empa-Eawag's on-site heating network 24  MWh / a 67  MWh / a
Utilisation of waste heat and commercial cold 7  MWh / a 16  MWh / a
Output of vacuum tube collectors (50 m²) 24  MWh / a 26  MWh / a
Electricity consumption of servers 219  MWh / a * 129  MWh / a **
Electricity consumption without servers 121  MWh / a 195  MWh / a
Electricity generated by the photovoltaic installation (459 m², 77 kWp) 60  MWh / a 71  MWh / a
Total grey energy
12000  MWh
Grey energy (average service life 37.6 a)
19  MWh / a

* Planning for server performance: 25 kW

**Server performance 2007: 16 kW (2009: 20 kW)


Sustainable water management
Collecting and reusing rain water on the roof of Forum Chriesbach saves valuable drinking water - annually approx. 400-500m3. It is only used for meal preparation in the staff canteen, for the water fountains located around the floors and for washbasins.

The open water garden (80m3) is located between Forum Chriesbach and the building of the Children Pavilion. It serves as a storage for rain water that is harvested on the green roof and slowly drained off, so that contaminants from the facade and the environment are retained. In addition, eco-friendly material has been used for the lining of the roof. The rain water collected this way is fed by separate pipes to the toilets for flushing. At the Forum Chriesbach building NoMix toilets are installed, i.e. urine and faeces go separate ways. The urine is collected in tanks and used to produce the recycled fertiliser aurine. This is made possible by the separate collection and treatment of urine, which also reduces the burden of micropollutants on the environment. You can find more information about this process on the website of the VUNA project and the spin-off Vuna GmbH.




The chronology "Eawag Forum Chriesbach, a 'sustainable' new building" can be ordered from Bob Gysin & Partner BGP Architekten at a price of CHF 35 (plus CHF 5 shipping costs).


These images may be used free of charge only in connection with reports on the Forum Chriesbach. (Source: Eawag)

Building owner and companies involved

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