Description

The new headquarters for Alnatura marks the beginning of the transformation of the former Kelley barracks site into what the green Mayor of Darmstadt intends to become a new “sustainable quarter with a commercial focus”. Alnatura wanted to play a pioneering role on the former military site, vacated by US forces in 2008, and to this end the city produced a development plan for the Alnatura site, which also includes a public Waldorf kindergarten, lettable allotments and a teaching garden along with an undulating park landscape.

The client wanted a building that is “inviting and open, rather than impressive”, that has the “atmosphere of a workshop” and that is “simple” in its construction. The latter translates as meaning it should employ as few complex building services as possible and minimise the consumption of resources. A central criterion for determining the materials used, therefore, was to consider their respective life cycles over an assumed period of use of 50 years. To begin with even the use of earth was not a given. Only after considering all aspects – from grey energy to recycling after demolition – did the client and architects elect to use rammed earth provided by the Vorarlberg-based earth building expert Martin Rauch. The fact that this use of earth was not an approved building material in Germany at that time – DIN standards exist for earth mortars, plasters and paints but not for rammed earth facades – made a number of special approvals necessary. The building’s north and south facades are constructed of rammed earth. 384 separate rammed earth panels, each 3.50 metres long and 1 metre high, were stacked into 32 self-supporting elements and anchored to the floor slabs with threaded rods. The individual elements were prefabricated by Martin Rauch’s team in a neighbouring hangar once used to park tanks. Thanks to the moisture-regulating capacity and thermal mass of the rammed earth façade as well as natural ventilation using air drawn in from nearby woodland and pre-conditioned via an earth channel, the interior working environment has a pleasant indoor climate in summer.

The rough surface of the exposed rammed earth also serves as a sound absorber and dissipator in the interior. The spacious all-round space of the interior extends from the ground floor to the ridge of the roof, 19 m above ground, and is designed for 500 employees, of which around 400 are permanently on site. The noise they generate means that almost every surface in the 13,500 m² building has some form of noise reducing function. The client also opted for a “non-territorial” office layout, designed by Vitra, with a desk sharing arrangement that facilitates flexible working constellations. One can work on “lounge levels”, in seating areas or other meeting “alcoves”, all reachable from the circulation areas and equipped with a mains connection. The open interior has a workshop-like atmosphere and only on the ground floor are there glazed partitions to separate off meeting areas and the canteen, which is open to the public. The glazed west and east ends of the building, as well as the large north-facing rooflight, ensure the interior is virtually as bright indoors as it is outdoors.

The mix of classic pieces of furniture from Vitra’s collection, surface-mounted installations (for example the sprinklers), pendant lighting (inspired by those in the former tank hangar), and the visible striations of the rammed earth walls create a working environment of such compelling character that one willingly overlooks the compromises that have been taken in the spatial design of the interior.

Originally published in Bauwelt 09.2019, pp. 44-49, abridged and edited for Building Types online, translated by Julian Reisenberger

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