Office tower, Vienna

The ÖBB has decided to build their corporate headquarters in the immediate vicinity of the planned new Vienna main station. Zechner & Zechner emerged as winners from the two-stage, EU-wide architectural planning competition. The structure will be constructed by the engineers Thomas Lorenz; the planning for the building's technical systems will be undertaken by Moser & Partner.

The aim of the competition was to find an outstanding planning concept for the corporate headquarters, which was to provide optimal working and communication conditions for the approximately 1600 employees from various ÖBB companies. On the lower floors of the building complex, central facilities and some external uses round out the office site's features.

The awarding body was keen to achieve an office and space concept that represented the state-of-the-art and complied with the following planning principles: the corporate headquarters should be efficient in its energy, space and construction costs, and in the environmental impact of materials used, also in its conservation of resources and their longevity, as well as sustainable because of flexibility of use and adaptability to various second and further users.

The international jury, including the architects Marcel Meili, Albert Wimmer, Marta Schreieck and Silja Tillner, as well as representatives of the City of Vienna and the ÖBB group, judged the project from Zechner & Zechner to be the best solution. The preliminary plan envisages an 88-metre-high tower as the frontage structure for the new district south of the planned main station. An S-shaped curve of the building and the recess at the site's northern border opens the structure to the forecourt. The dynamically curved main form and the smooth, rounded surface are reminiscent of modern high-speed trains.

The depth chosen and the configuration of the core allow maximum flexibility of the various office organisation options (groupings, cells, combination offices, business club). This allows the different organisational options to be realised, both within the building and on an individual floor, as a mixed office. The strategy of reversible offices has proven to be the optimal concept in terms of investment because of its high flexibility, which makes it easily adaptable to individual user's requirements.

Zechner & Zechner have designed a sustainable 'slim building' with low primary energy consumption and limited use of domestic engineering, while at the same time having a healthy and comfortable climate. Passive systems, such as thermal storage via component activation, adjustable external sun blinds, natural ventilation, heat dissipation via automatic ventilation, the redirection of light to optimise natural illumination and reduce energy consumption for lighting and natural humidification with islands of plants are used to achieve this. Heating and cooling is primarily via the pumping of air and water. Solar-powered cooling supports the office level cooling. Community heating and cooling are used to cover peaks in demand.

Further planning will incorporate resource usage and generation of waste, as well as construction related costs over the entire life cycle of the structure, in order to comply with environmental and economic requirements. This will be documented via obtaining the appropriate certification of sustainability.