The office of Rijkswaterstaat (the Directorate General for Public Works and Water Management) in Terneuzen is situated on the complex of locks on the Ghent-Terneuzen Canal. It accommodates some sixty employees of the Zeeuws-Vlaanderen regional department. Construction for this office started with a high level of ambition: it was to become a model office block for ‘human- and environmentally-friendly’ construction.
The highly sustainable and comprehensive design utilised sawn-off, discarded mooring posts for the outside wall and galleries of the atrium. The building is a wooden construction with the gaps filled with loam bricks, loam plaster and insulation made from old newspapers (cellulose insulation). The wood used for the interior walls and the frames in the exterior wall have been treated using natural linseed-oil-based paint. The building is ventilated using natural means and heat is generated by a heat pump that draws heat from the canal water. The atrium is fitted with solar cells to generate electricity, positioned in such a manner that they simultaneously serve as sun blinds. The interior reflects a great concern for environmental aspects. For example, the carpeting is made from wool and goat hair, and the desktops are made from bamboo treated with linseed oil and beeswax.
The design seeks to buffer rainwater and to minimise the amount of drinking water used and the amount of wastewater produced. The building’s situation on the locks complex meant that a pressure pipeline would be required for its sewers. That circumstance made it easier to pass the decision to have the building completely separate from the sewer system.
All the wastewater is treated locally, in two beds of reeds, and recycled for flushing toilets. Much of the roof water is buffered by the moss sedum roof, while the surplus is allowed to infiltrate through a soakway pit. Paving has been kept to a minimum around the building. Where paving is unavoidable, various forms of porous paving material have been used, such as gravel and woodchips.
The Terneuzen municipal authorities were not immediately sympathetic about this water concept. After having fought for years to have every farming business in the vicinity connected to the sewer system, the municipality found it difficult to allow the office of Rijkswaterstaat to operate without a connection to the sewer system. However, eventually it was possible to convince the Terneuzen authorities and the office was given a separate treatment system in the form of a helophyte filter.
All the household wastewater in the Rijkswaterstaat offices from taps and showers to dishwashers and toilets is led through a collecting tank, where the first breakdown processes and homogenisation occur, and into the reeds. The treated wastewater is used both for flushing toilets and for the water art. Water is used in the atrium: the gentle babbling of flowing water helps to create a pleasant atmosphere.
The system has proven to work well and without complications, and in terms of technology can be used elsewhere, too.
The system’s environmental yield is high, since it does not produce any wastewater and the amount of drinking water consumed is cut by two-thirds. The absence of pavement and the addition of a sedum roof offer benefits in both climatological and ecological terms.
The entire building is greatly enjoyed by its users, including the sustainable water concept. The building’s remarkable character and the design that incorporates the users’ specific wishes and its surroundings combine to provide the users with an unusual building that sets them apart. Pötz et al., 2009