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Selected Projects

Power Tower - Energie AG Headquarters
Client: Energie AG OÖ
Location: Linz 2004 - 2008
DNGB GOLD certificate
Prime Property Award - Shortlist 2010
Green Good Design 2010
Emilio Ambaz Award 2010 - Project of the Year
Austriam FM Awards - ATGA Facility Award 2010

Videolink: PowerTower rooftop swing (Parov Stelar)>>

Self-sustaining office power station
Energie AG´s Power Tower

An architect working for an energy company has to deal with resources in an exemplary fashion. The new Energie AG headquarters shows what is possible with the very latest technology. The Power Tower is the first self-sustaining, passive-energy tower block in the world, meeting its own energy requirements from sun, soil and water.

A concept developed by Weber & Hofer AG in an architectural competition for the Energie AG headquarters was implemented by Kaufmann / Partner, setting new criteria for the use of renewable energy forms.

Urban planning situation
From an urban planning standpoint, the project stood out as a clearly structured building that accentuates the beginning of the station district and combines with the Provincial Centre for Public Services to form a coherent gateway to the station area. The slim, 70 m-high building with a two-storey surrounding structure fits beautifully into its immediate environment and the road network.

Architecture and engineering
The Power Tower is not only an important urban accent, but also a pilot project for consistent implementation of energy efficiency and sustainability. The first self-sustaining, passive-energy tower block in the world, it will house 600 employees. Almost the entire energy requirement will be met from renewable sources. In collaboration with the industry, Kaufmann / Partner played a decisive role in the development of the energy concept, especially the completely new façade elements – a new interpretation of the classic double-glazed window.

Energy concept
The three-part energy concept – shell, house automation and energy supply – cuts down on 300 tons of CO2 emissions annually, thus making a lasting active contribution to climate protection.

The multifunctional façade construction consists 60% of glass and 40% of high-insulating materials, thus achieving lower heating and cooling requirements, so that the building needs no air-conditioning. At the same time, the glazed façade admits maximum daylight, minimising the need for artificial lighting. The façade is constructed in three layers, with a new integrated sun-protection system. Innovative blinds allow a view outside, and admit daylight even with maximum sun-protection.

House automation
Although the house automation in the Power Tower will provide a healthy and pleasant room climate, the energy requirement for heating and air-conditioning is reduced to a minimum. The entire system uses only half as much energy as comparable systems in buildings of similar size. It offers special features which were until then non-existent in this overall conception. An excellent working climate is ensured by suspended radiant cooling ceilings without air circulation, radiators with individual thermostats, and fresh air supply with controlled ventilation with an imperceptible air-change rate of 1.5 ac/h.

Energy supply
The novelty of the energy supply for the Power Tower lies primarily in the combination of approved technologies used here for the first time. Heating, cooling and ventilation of the building are effected through a combined heat pump system which extracts its power from soil, water and sun. Geothermal power covers the Power Tower´s basic energy requirements. For heating and refrigeration, the energy is extracted from the soil by means of deep probes. Here the special feature is that the heat generated in summer during the cooling period is pumped back into the soil, and in winter the natural storage capacity of the soil can then be used for heating. Especially in the transitional seasons, this system enables efficient energy exploitation. Parallel to this, energy is extracted from the ground water through two well-heads. This cooling water is used primarily for the data-processing centre and the fresh-air supply. The solar power plant to the south-west of the building covers almost the entire façade, from the first floor up to the roof, leaving out only the fire stairs. With an area of some 700 m², this is one of the largest solar power systems in Austria; it produces 42,000 kWh of electricity per annum, and provides a considerable proportion of the power supply to the offices.

Master design: Weber + Hofer AG, Zürich
Lighting Art: Norbert Pfaffenbichler, Lotte Schreiber
Photos: Dietmar Tollerian, Kaufmann | Partner
Text: Norbert Tomasi