As the central concept for the corporate headquarters of Energie AG OÖ it was a definite priority to create an innovative and unique energy concept. The Power Tower is the first office tower worldwide with passive house characteristics.

The paradigm for energy efficiency is 75 meters high and with its 19 storeys stands proud above the three floor podium. The building makes an important statement within its surrounding landscape acting as a link between the nearby Volksgarten and the busy district around the station .

No fossil fuels for heating and cooling

The energy for the building is particularly resource-conserving and is extracted using geothermal techniques from the earth and subterranean water. A significant contribution to the operation of the necessary heat pumps comes from Austria’s largest facade-integrated solar energy installation on the South-west wall of the Power Tower.

The premise for the self-sustainable alternative energy was a complete energy concept comprising optimally oriented energy harvesting, ingenious utilities management and an optimised building envelope.

Multi-functional glass facade

Only 40 % of the facade surface comprises high thermally insulating opaque panels with the other 60 % being transparent glass facade. The particular challenge to achieve vision, glare-protection and solar control without compromising on natural daylight was mastered using state of the art technology.

The extremely good insulation value of Uw 0.6 W/m².K of the facade is typically achieved using triple glazed CLIMATOP glass elements at a distance of 12cm to the outer sheet of SECURIT-H which is connected using an aluminium profile. The sealed cavity is actively conditioned. This technological development has been sucessfully employed on this project. In total, about 4,400 m² of CLIMATOP energy saving glass and 6,100 m² of SERALIT LITEX-H using low-iron DIAMANT glass was supplied for the typical facade. The podium levels have very large CLIMAPLUS insulating units. All insulating glass units incorporate CHROMATECH PLUS warm-edge spacer bars.

The low cooling load is achieved using louvre blinds which in combination with the high-performance glass units bring a 85-90% reduction in solar energy gain. With the special louvre geometry from RETROflex, a simultaneous improvement in vision is achieved. The result: the uniform interior daylighting brings a significant reduction in energy use for artificial lighting.

A 640 m2 sized Solar energy power station covers almost the complete south-west facade. The particular advantage of this BIPV installation is its dual functionality – weather protection and energy production on the one hand, and on the other a synchornised power production curve in harmony with the load curve of the building.

During darkness, the Power Tower shines with 700 LED strips which are integrated into the facade. The „Art in Building“ installation uses about as much energy as a household vacuum cleaner.

The building developer has made a clear statement about their leadership role in sustainable and energy-efficient construction. This has been underlined by the expected ÖGNI (Austrian Society for Sustainable Building) certification.

(Photos: Energie AG)