AZPML wins Austro Control Headquarters Tower Vienna

Description of the project by AZPML and SHARE Architects

The form of the tower has been designed as an airfoil to minimize the impact of the wind on the structure, and to minimize the downdraft. The basic plan of the tower adopts a diamond shape, which is oriented in direction Northwest-Southeast, to follow the prevailing wind directions in the area.

Taking as a constraint the Southeast edge of the site, we have built through mirroring a footprint which contains 1028-square-meters of gross area. When mirroring that edge along an axis parallel to the Schnirchgasse, we have automatically obtained a triangular plaza on the southernmost tip of the site, which will act as entry plaza to the new tower… The rest of the site has been covered by a double height socle which contains the convention centre, the public parts of the program and some services to the building. Below grade, we have located four levels of carpark, storage and mechanical services.

The effect on the skyline from the Prater is akin to a tapering wing, a simple and elegant but unique skyline. This characteristic silhouette will also contribute to articulate the direction of the University Complex towers with the triangular shape of the ORBI tower.

The building envelope has been designed in order to optimize its environmental performance. It is constructed with a triple glazed envelope, in which there is an external single layer which encloses a 300-millimeter air chamber containing variable louvers to protect the skin from solar radiation while allowing maximum transparency when possible. The inner layer of the envelope is built with standard double glazed, aluminum framed units. While the mullions of the inner, double glazed skin are running vertically on a 1,40-meter grid which will allow maximum flexibility to install interior partitions, the mullions of the second layer have been laid out in parallel to the sliced edges of the form. Both systems of mullions are therefore producing a diagrid with a very acute angle, which operates visually as a moire veil, aimed to further de-stabilize the gravitational affect of the structure.

In terms of environmental performance, the envelope system will allow for natural ventilation of all spaces in the building. The external mullion system will regulate the ingress of air into the air chamber, from where a decentralized ventilation system will process the air and feed it into the functional spaces. The air will be preheated or precooled as it is fed into the building from the façade perimeter, eliminating the need for air ducts, and allowing to maximize the height of the space. The exhaust air will be collected around the central core and extracted to the roof through several ventilation ducts. This will minimize the energy required for ventilating, heating and cooling the buildings. There will be no air-based heating and cooling system in the buildings. All temperature control will be provided by radiation.

The buildings will have a concrete structure, which will contribute substantially to their environmental performance. Cooling will be provided by cold water coils embedded in the concrete slab, acting as radiators. Heating will be provided by the distributed ventilation units.

The public realm of the tower is conceived as a banded pavement which emerges from the geometry of the building. The banding of the pavement is designed to accentuate the strong shape of the tower and emphasize the convergences of routes which occur in the plot. The paving is materialized in a granite letterbox shaped blocks of mid grey color. The lighting and the surface water drainage channels will also follow these lines of banding.

This banding starts in the tower and colonizes this new shared pedestrian space around it, generating a new pedestrian friendly space which connects to the neighbor buildings and the nearby underground station.