The new headquarters of sporting goods and outdoor gear manufacturer Dynafit in the Bavarian town of Kiefersfelden consists of two roughly 30 m tall prisms. Facing each other, they occupy a footprint of 25 by 56.5 m. Their strongly inclined facades intersect by 10 m, producing an emblematic shape recalling stylised mountain peaks. In their design, the architects of the Spanish office Barozzi Veiga explicitly refer to the surrounding Alps near the German- Austrian border. The landmark, situated along the perimeter of a commercial zone next to the Inntal highway, reminds its observers of the fact that the company creates mountaineering products. The new Dynafit building is comparable to the headquarters of Salewa in Bolzano in South Tyrol. This is no coincidence, since both companies are managed by the Oberalp Group. The prismatic volume houses six office floors, each successive one smaller than the one below, and includes a brand experience space complete with climbing hall, restaurant, daycare centre and penthouse.
Passive shading system
The building design is based on a concrete frame with two stiffening access cores. The volumes appear simple, yet feature a spatially complex interior with multi-storey areas. The facades to the east and west are inclined by 61° and nearly completely glazed, affording visitors panoramic views of the mountains. The vertical rear and lateral facades of the building comprise very few windows. The degree of openness of the interiors and the view of the Alps desired by the client resulted in questions decisive to the design: How to prevent summertime overheating, despite 1450 m2 of glazing? How to meet the requirements for energy efficiency, while keeping cooling loads as low as possible? Barozzi Veiga didn’t wait until after the conclusion of the design phase, but instead, invited the Stuttgart-based engineering office of Knippershelbig to join at the beginning of the two-stage architectural competition. The professional engineers, specialised in facade technology, contributed to the concept and design of the building envelope as well as its technological implementation.
Initial considerations led the planning team of architects and engineers to propose a double skin facade with either exterior or integrated movable sun protection. These concepts were abandoned due to the costs for production and the effort for cleaning and maintenance. A further criterion that led to deciding against any type of movable exterior sun protection was that it would impair the monolithic visual impression of the building. The task was therefore to develop a cost and energy efficient single skin glass facade with fixed sun protection elements.
Folded facade structure
In a first step, the team identified from which direction and at which angle direct sunlight would hit the glass facades oriented eastward and westward. The engineers analysed the global radiation on site according to parametrical 3D models and local climate data. Based on the main sun direction according to its annual average during summer and winter months, they developed a folded glass surface. For each side of the building, this resulted in an individual jagged geometry. The structure of peaks and valleys was complemented by transversely arranged perforated shading panels of pentagonal shape. They reduce the degree of direct sunlight intake on the eastern facade by about 53 % and even by about 63 % on the western side. The jagged geometry refers to the Bavarian Alps, while creating a homogeneously dynamic interplay of light and shadow across the building envelope and the interiors.
The greatest advantage the free standing, uniformly perforated shading panels offer, aside from the comparatively low costs for production and maintenance, consists in reinforcing the strong architectural gesture of the building. Perforating the panels was indispensable in order to permit sufficient daylight to enter and also serves to keep contrasts low between sunny and shady areas. Additional interior textile curtains prevent glare from affecting the office levels.
To further support the homogeneous building impression, the vertical facades were realised as back ventilated constructions with thermal insulation that are also enveloped by the uniformly folded structure. Here, it serves as sun protection only in few partially glazed areas. The greatest challenge in terms of design was to harmonise the jagged geometry enclosing the building with transitions intended to be flowing and seamless. Along building corners and the roof ridge, smooth sheet metal coping produces calm, linear edges.
Facade construction and glazing
Once the geometry of the glass facade and the shading elements was defined, the next step focused on the facade load bearing structure. It was necessary to develop a steel construction that was vertically detached from the ceilings in order to prevent undesirable load transmission from the ceiling slabs. The result was a structure resembling a ladder, comprised of steel rectangular hollow sections with rigid connections to the primary reinforced concrete frame along its sides and bottom. The “steel ladders” were attached diagonally to the facade surface. Prefabricated in the workshop, they were welded into components measuring about 3 × 6 m, delivered to the construction site by trucks and lifted onto the building by cranes.
In follow, the remaining intermediate parts and bolted connections were applied. Eventually, this produced a uniform folded geometry. The ladder structure serves as the load bearing component of the mullion transom facade. It supports triple sun protection glazing, which also offers the required soundproofing against the traffic noise from the highway. For the steel brackets applied to the ceiling slab edges, a solution was necessary that would enable sliding facade connections and prevent flashover in the case of fire. This was achieved by cladding the interstitial space between ceilings and facades with gypsum board.
Due to their 61° inclination, the glass surfaces are classified as overhead glazing. The interior panes therefore consist of laminated safety glass. The rhomboid elements measuring up to 1.2 × 3.3 m continue without interruption across multiple transoms in order to reduce assembly expenditure. Transoms in between merely perform construction-related purposes. All glass elements were adhesively bonded according to the structural glazing principle. Cover bars were omitted. The glazing features additional mechanical point fixing with occasional clamps that are hardly visible, even at a closer view. The approximately 160 cm wide and 70 cm tall pentagonal sails connected to the facade posts at a distance of 1.5 m consist of 2.5 mm thick powder coated sheet aluminium.
Cleaning and maintenance
The inclined glass facade features only very few openable sashes. They would be difficult to operate by hand, due to their weight. However, electrically powered openers as an alternative are costly. Beyond that, it was easier to arrange windows and openable sashes in the vertical facade areas, supported by uniform building uses across floors. The dining and assembly hall on the first floor features conventional vertical glazing with an adjacent outdoor terrace, covered by the shading panels of the inclined facade.
The expectation is that the glazing, due to its strong inclination and the related self-cleaning effect, won’t become too dirty. In fact, filth, dust and other dirt deposits are hardly perceivable, due to the vivid facade geometry and the reflections of the silver aluminium panels within the glazed surfaces. Should it be necessary, the sheet metal facade permits relatively simply cleaning, due to the distance between it and the pentagonal panels. Dynafit opted neither for rail based facade maintenance systems nor other more elaborate and costly built solutions. Instead, the mountaineering company placed its bets on the joy of climbing among its staff members. For them to abseil from the roof ridge, the shading panels needed to be sufficiently robust in order to prevent damages due to resulting additional loads. The engineers achieved the stability required for this purpose by amending the 2.5 mm thick sheet aluminium panels with lateral canted edges.
The sports and outdoor gear manufacturer Dynafit received a building that is a symbol for its business in every conceivable manner. It draws the mountain landscape inside, both conceptually and visually. This is complemented by a low tech facade that only became possible through high tech, which corresponds to the unobtrusive spirit of innovation behind the company’s products. The building also constitutes a landmark. Due to its very minimal design of great clarity, it is highly memorable. This effect is reinforced by its location next to a highway, frequented annually by millions of people from all across Europe, travelling from the lowlands to the mountains.
