The Power Tower in Linz, Austria is the first office tower to attempt to meet the Passive House standards.
This visit was part of the Renewable Energy Research Trip to Austria that took place in November 2011.
The Power Tower was built to house the corporate headquarters of the Austrian utility company Energie AG. The new offices were built from 2006 to 2008 on the same location of Energy AG previous headquarters built in the 1930s. We were told that when they demolished the original building everything that was possible to reuse it was kept and used in the new building.
Energy Systems
The Power Tower is not dependent of fossil fuels. The energy is obtained through the soil and the ground water, and/or generated by the solar panels that are integrated into the façade.
Façade
Dieter Moor from Ertex Solar was our guide for this visit. He explained the façade was specifically developed for this project and 90% of the solar heat remains outside the building, therefore it was not necessary to install a conventional air-conditioning system. The building envelope was specially engineered to allow maximum day lighting while minimizing solar gain, which would normally be excessive and require a great deal of active cooling.
The façade system is made of enclosed panels (with no access), quadruple glazed, and the outside pane has two glass panels laminated together. A small device inside each module sucks the air and moisture. The U-Value is 0.5 W/m².
60% of the Power Tower façade is transparent, the remaining 40% have an opaque surface highly insulated.
The South façade has three vertical photovoltaic bands that cover approximately 650m² and generate about 42,000 kWh of electricity per year (10% of the building’s energy).
Heating and Cooling
A combined heat-pump plant provides 100% of the energy to the heating, cooling and ventilation systems of the high-rise office building.
Power Tower - Plant Room
Power Tower - Plant Room
The soil and the ground water are used as thermal sources. Depth probes and foundation piles extract the energy for heating and cooling from the ground.
Power Tower - Manifold for the 46 geothermal wells
Beneath the building, 46 geothermal wells, each 150 m deep were drilled prior to construction (this is nearly 7 km of boreholes!).
As a special feature the heat accumulated during cooling operations in the summer is pumped back into the soil and can be used for heating in the winter.
Ventilation
Heating and cooling panels with radiation effect are suspended from the ceiling. A controlled ventilation system supplies fresh air, as the windows of the building cannot be opened.
Lighting
A total of almost 700 LED lighting elements were installed, which create extraordinary light effects. This artistic light installation uses a maximum of 1.4 kW, which is less electricity than is consumed by a commercial vacuum cleaner.
Power Tower - Internal Courtyard
Fact sheet
Gross floor space: 32,872 m² (incl. underground garage)
Façade surface: 11,620 m² (of this photovoltaic surface 637 m²)
Height of tower: 73 m
Number of floors in tower: 19
Number of floors in underground garage: 2
Number of garage parking spaces: 246
Maximum heating output: 700 kW
Maximum cooling output: 800 kW
Construction costs: €42 million euro (excludes sustainable energy grants)
Isabel Barros
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