Clever Construction at Nordwesthaus

Clever Construction at Nordwesthaus Faith Westhoven

Ground floor plan, second floor plan, and reflected ceiling plan

The port of Hafen Rohner, also known as the Rohner Yacht Harbour, is not one to go unnoticed among the sailing community in southwestern Austria. Located within the scenic Rhine Delta Nature Conservation Zone, this small port on the edge of Lake Constance has become an irreplaceable meeting place for seamen and community members alike (Lentz). But, it wasn’t always this way. Large gravel pits used to inhabit this land under the ownership of a prosperous aggregates company that fell in 2003. That is when current owner Maria Rohner took over, undertaking the challenge to turn the stony eyesore into a picturesque destination. Maria hired local architecture firm Baumschlager Eberle, and with their help, devised a master plan to transform the port in three stages. Stage one included the design of a cantilevered office building, custom made for Maria. This building is a linear concrete tube that 2

seems to hover over the landscape while framing the view of the water and, later, the Nordwesthaus. Stage two consisted of a drastic redesign of the adjacent shoreline, which in turn facilitated stage three: the creation of the Nordwesthaus (Hudson).

Design of Nordwesthaus began in December of 2004 and did not cease until March of 2007. The result of the architect’s efforts consisted of a concrete skeleton encased in a crystalline glass box, rising 14 meters high out of Lake Constance. Interestingly enough, the construction process of the Nordwesthaus began with that of the new harbor quays in 2006, as it was convenient to break ground for the two phases simultaneously.

After this, the submerged building foundation sat untouched for nearly 1.5 years, due to issues with Fussach zoning laws. Because the selected site for the new building jutted out

Comparison of the Nordwesthaus eastern elevation with the office building east elevation

Site map showing the relationship of the Nordwesthaus to its neighboring office building.

into the water, building regulations required the facility to function as a boathouse accessible by water.

Baumschlager Eberle, whose design did not initially include a “boat box”, took ample time to redesign. There was no time limit on the process because the building was commissioned with no use in mind (Bruijn).

The Nordwesthaus as it stands today is a two story building with a 117 m2 footprint (A+U). The ground floor contains a bathroom, storage room, and a boat parking spot. The second floor, situated approximately 5 meters above the ground and with an 8.8 meter high ceiling, is a primarily empty multipurpose room; the only permanent interruption in the open floor plan is a single staircase and a custom made kitchen island. The boat house, with its vertically tall stature, poses as an opposite to its neighboring office building, which is long and cantilevered. In fact, creating opposites is a reoccurring theme in the design of the Hafen Rohner, and Baumschlager Eberle continuously compares the Nordwesthaus with both itself and the entirety of the port. The flowing design of the building’s concrete walls

(Below) View of the Nordwesthaus from the window of the office building.

mimic nature, specifically the trees and water surrounding the site, yet poses as a stark contrast to the linear elements of the adjacent office building and new harbor quays. Its organic concrete contours are wrapped in an envelope of orthogonally organized glazed panels, revealing a difference

between the shell material and the structure. To soften the contradiction, the glass panels are arranged in a staggered pattern, appealing to the randomness of the concrete forms beneath. The material choices of glass and concrete in combination with each other provide ample light to 3

Northeast corner building section

the interior at daytime, and have the reverse effect at night, exposing the internal weaving skeleton to the port (Lentz). This x-ray effect showcases a strong core coexisting with a soft exterior. Even the building’s walls can be compared and contrasted; the east wall is a reverse mirror image of the west wall, and the north wall of the south wall.

The budget for the Nordwesthaus was set at roughly EUR 500,000 (Bruijn). Through many investments and returns, it is hard to estimate the exact amount that the building cost, especially given that Baumschlager Eberle had collaborated with several third party consultants. However, it is known that they stayed within budget, and this is apparent through their extensive financially sparing efforts (Bruijn). The architect’s intentions to keep building costs low almost always doubled with sustainability efforts as well. For example, they put limited technical systems into the building, with few artificial lighting elements. During the day, natural light pours through the wall openings into the clubhouse interior, eliminating the need for the lights to be on. At night, recessed can lights illuminate the event space from the ceiling, 4

Formwork end piece example

while 125 LED spotlights placed at the façade’s edge brighten up both the interior and the exterior with any color imaginable (Lentz) (Hudson).

Further synergies between financial and environmental resolutions, the architect made a decision to have no electrical heating or cooling system installed, instead relying on the material choices, breaks in the facade, and weight of the building to maintain thermal comfort. The concrete walls are 25 centimeters thick, which stores and releases ample heat through the time lag effect. There are six windows on the glass box strategically placed across from each other to welcome cross ventilation for natural cooling (Bruijn).

Limiting electrical systems helped maintain the budget, but Baumschlager Eberle’s greatest contribution to save money and energy resides in the concrete formwork. The design for the concrete façade covers a total of 147 m2, with a carved pattern that is complex and seemingly random. To create custom formwork for each and every perforation in the wall would have pushed Baumschlager Eberle well over their target budget; waste from both the equipment allowance and the formwork

Examples of individual formwork pieces Faith Westhoven

Section cut showing the construction process of forming the concrete curvatures

itself would reach vast amounts.

Baumschlager Eberle avoided these issues by dividing the concrete pouring of the building into different stages of construction. The underwater foundation was the first stage, set in with the redesign of the shoreline as mentioned above. This process involved prefabricated concrete piles that were shock driven deep into the harbor basin, the top of which then provided a dry plane for the continuation of construction (Bruijn). The next two concrete pours further elevated the building above the water, and made up the slab for the ground floor.

The remaining building stages, which would make up the four undulating concrete walls, were subdivided into five sections in elevation and two sections in plan – amounting to a total of ten concrete pours (Ulrich). Because each opposite elevation is identical, the two sections in plan use the exact same formwork pieces.

The first step in erecting the walls was to configure the formwork parts.

Clever Construction at Nordwesthaus

Baumschlager Eberle, in collaboration with the general contractor, created a modular system of formwork elements only 60 centimeters long, and 25 centimeters in width. The pieces in this system had only three different radii varying among them, with each radii having one convex and one concave version of itself – amounting to a total of six different designs (Hudson). They used replicas of these six elements in various combinations to create all of the shapes of the apertures. The formwork pieces were crafted with Nordic birch plywood, coated in a high quality phenolic resin film, and framed in oil coated steel form parts (Bruijn). The exact number of individual formwork pieces they had created is uncertain, however, it is known that they had enough pieces to wrap half of the building perimeter once and reach up to about 2.8 meters high. In other words, they had enough formwork to complete one stage at a time, reusing the parts in each ascending stage until all ten pours had been completed.

The five elevation sections, although similar, were not exactly equal in height. Instead, they were divided based upon the curvatures in the wall and what formwork pieces would be available to make those curvatures.

With that being said, considering the factors of section height, the frequency of the openings and their diameters, the two pours made in the fourth elevation section required the most formwork. The perimeter lengths of the apertures in one of these pours amount to about 85 meters. Given that each formwork piece covered 60 centimeters of ground, this pour alone required about 142 pieces of formwork. Since elevational section four is the largest of the five, it is assumed that the minimum number of formwork pieces created was around 142.

Looking at the building as a whole, the concrete walls contain a total of 116 openings, excluding one for the front door and one for the boat water entrance. The perimeter lengths for these openings add up to ap5

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Drawing showing the breakdown of the five elevational pour sections

proximately 726.6 meters. Had the 60 cm formwork pieces not have been reused, the design would have required an estimate of 1,211 pieces of formwork to cover all 726.6 meters.

In creating a flexible modular formwork system, Baumschlager Eberle saved an estimate of 1,069 pieces of formwork and about 88% of the cost on formwork matierals.

As the small form parts were secured into place, they were held together by flat walls composed of PERI steel panels on both the interior and exterior sides (Hofmeister). Wooden shuttering was wedged in between 6

the formwork of each opening.

Before the concrete was poured, any electrical installation, water drains, or reinforcement were placed. The steel reinforcement had 20mm casting spacers, and ran above, below, and in between each curved opening.

Once all internal operations were set, the concrete was poured, and appropriately cured before the process repeated itself. Once all ten sections of the concrete wall were erected, the building was close to completion.

Next, a steel frame box was assembled around the concrete in which the glass panels sat. The Sika® Sarnafil® roof followed, with electrical installa-

tions and lights embedded. Window opening winches were applied and steel doors were installed wherever necessary, thus concluding the construction process (Bruijn).

There were few downsides to Baumschlager Eberle’s approach to construction. As much as the reuse of formwork pieces saved material and budget, it did not save time. The process of removing and cleaning the pieces was time consuming, and subsequently required more labor. Labor costs rose, considering the process of pouring, removal, cleaning, repair, and quality control took several Faith Westhoven

All four building elevations unfolded

Hypothetical possibilities of elevations that could be crafted with the same formwork pieces

months. To combat rising expenses, the architecture office of Baumschlager Eberle took on the responsibility of doing much of the construction work themselves (Bruijn).

In the design of the Nordwesthaus, repetitive formwork served nonrepetitive shapes, and the limit on this concept does not end here (Hofmeister). Structurally, the Nordwesthaus uses the vertically consistent sections of concrete as loadbearing systems.

There are three load bearing sections in each large façade, and two in each smaller façade. Lateral stability is reliant on the second floor slab. As long as the formwork pieces are available and structural integrity is maintained, there is no limit on design possibilities with this method. Baumschlager Eberle has discovered a creative solution for complex construction, and if continued, could be a glimpse into a sustainable and financially smart future of architecture and design.

Clever Construction at Nordwesthaus

Demonstration of the glass panel overlay on the concrete

Bibliography “Baumschlager Eberle: Nordwesthaus, Fussach, Austria” Kenchiku to Toshi = Architecture and Urbanism: A. + U., Vol. 6 Issue 465, 2008.

Bruijn, Willem. Personal Interview. 13 September 2019; 2 December 2019.

Dangel, Ulrich. Sustainable Architecture in Vorarlberg: Energy Concepts and Construction Systems. Basel: Birkhauser Verlag AG, 2010.

Di Bartolomeo, Massimiliano. “Clubhouse, Fussach - design: Baumschlager Eberle” Domus, 2009.

Hofmeister, Sandra. “Lichtspiele im Yachthafen” Baumeister, 2009.

Hudson, Jennifer. Architecture : From Commission to Construction. London: Laurence King Publishing, 2012.

Lentz, Linda C. “Baumschlager Eberle’s Nordwesthaus Casts Its Reflection on a Quiet Corner of Lake Constance” Lighting: Special Effects, Vol. 197 Issue 11, 2009.

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