Heating and Cooling
A combined heat-pump plant provides energy for
the heating, cooling and ventilation systems of the
high-rise office building. 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. As a special feature, the
heat accumulating in summer during cooling operations is pumped back again into the soil and can thus
be used for heating in winter. Two feed pumps supply
additional cooling energy from the ground water,
which is used mainly for the computer center, as well
as to operate the fresh-air supply.
Data and Facts
The building two-floor annex,
19-floor office tower,
two underground garage levels.
Built-up surface: 3,753 m²
Net floor surface: 22,652 m²
Gross cubature: 124,282 m³
Maximum height of complex: 73 m
Energy façade
60% transparent surface; innovative sun
protection with simultaneous supply of
daylight while affording a view to the outside,
40% opaque surface,
with high thermal insulation
Building technology
Suspended ceiling panels for heating
and cooling with radiation effect.
Fresh-air supply from controlled ventilation.
No power air-conditioning.
Maximum heating output: 700 kW
Maximum cooling output: 800 kW
Energy generation
Energy source: soil and ground water from
•6,900 m of depth probes
•900 m of activated foundation piles
•2 ground-water feed wells
100% of heating and cooling supplied by
combined heat-pump system.
Heating with “geothermal heat”:
1 kWh of electricity (to drive the heat pump) and 3 kWh of
emission-free geothermal heat are used to produce appr. 4 kWh of
heat that is available to heat the building.
Cooling with “geothermal cold”:
1 kWh of electricity (for the circulating pump) transports
up to 50 kWh of “cold” – free cooling
Solar power station of 650 m² on the photovoltaic façade.
Certainly, the challenge in building
the new corporate headquarter of
Energie AG was, on the one hand,
to put the overall building structure,
as designed by Weber + Hofer, into
concrete architectural details and to
further develop the project in line
with local building regulations and the general conditions
of the building sector and, on the other hand, to create
high-quality and pleasant working conditions for the
company’s staff. We developed a façade with a completely
new technology, which integrates light art. We designed
clearly structured and transparent work stations and, last
but not least, we built Europe’s first office high-rise building with passive-house characteristics. All these factors
underline the image that Energie AG projects of itself as a
modern energy supplier.
Power Tower
The new corporate head office sets new standards.
Power Tower - Project Data
Ground surface
3.753 m²
Net floor space
22.652 m²
(not incl. underground garage)
Gross floor space
32.872 m²
(incl. underground garage)
Gross cubature
124.282 m³
(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 annex
2-3
Number of floors in underground garage
Number of garage parking spaces
2
246
Prof. Arch. Wolfgang Kaufmann
Jürg Weber
Josef Hofer
We were guided by several factors in parallel when working on our design: To make room for all companies of
the group under one roof. This facilitates short distances
and optimum interaction within the corporation. Another
important element was to facilitate the sustainable use of
energy. The clearly structured high-rise building is a major
boost to the attractiveness of the neighboring residential
buildings. Moreover, the reflecting façade sections underline Energie AG’s image of open-mindedness and add a
specific touch to the fast-booming area around the central
railway station.
Jürg Weber
Josef Hofer
Ground broken in
spring 2006
Construction time
March 2006 – August 2008
Solemn inauguration
28/30 August 2008
Relocation to building
8 September 2008
Building owner
Power Tower GmbH on behalf
of Energie AG Oberösterreich
Project management
Alois Siegesleitner
Hans-Peter Schmid
Technical management
Reiner Kaltenhauser
Design of the building structure
Architekturbüro
Weber & Hofer, Zurich
Design of façade, interior
Architekturbüro
and detailed planning
Prof. Kaufmann & Partner, Linz
Energie AG Oberösterreich
P.O. Box 298
Böhmerwaldstrasse 3, A.4021 Linz
Phone: +43 (0)732 9000 3323
Fax: +43 (0)732 9000 3205
www.energieag.at
The New Corporate Headquarter
Sets New Standards
The new corporate head office of Energie AG Oberösterreich – the “Power Tower” – heralds a new era for the energy
efficiency of big office buildings.
By building the new corporate headquarter in the prospering area around the central railway station of Linz, the
regional capital, Energie AG is sending a clear signal. The
“Energie AG Power Tower” indicates that we are a company with regional roots, as well as with successful and
innovative international operations.
Energie AG is an infrastructure group with operations
throughout Europe. It is fully committed to its home base
in Upper Austria. Quite deliberately, we therefore decided
to keep our location at Boehmerwaldstrasse, which is rich
in tradition. With the extraordinary appearance of our new
corporate headquarter we contribute to the architectural
diversity of our regional capital. The modern architecture
is a reflection of our progressive and aspiring group of
companies. At the same time, the artistic design of the
high-rise office building creates a hallmark. In the first
place, though, the Power Tower is a building that points to
the future and sets an example in energy technology – it
is the first office building in the world with passive-house
characteristics.
All Group companies are once again united – under the
roof of the Power Tower. The new work stations offer
optimum working conditions to all employers and are the
basis for a successful future.
Dr. Leo Windtner
CEO of Energie AG Oberösterreich
The Power Tower is not only a hallmark in the cityscape of the
booming area around the central railway station of Linz and a
modern headquarter for a vigorously expanding infrastructure
group, but it is also a unique pilot project for implementing
the efficient use of energy with consistency and sustainability.
The Power Tower is the first high-rise office building worldwide that was built with passive-house characteristics. The
new corporate headquarter does not need connecting to any
district-heating system and manages without using any fossil
energy for heating and cooling purposes.
The design model by Weber/Hofer, architects from Zurich,
was the project that won the international architectural
competition. A careful examination of several building options preceded the decision to construct a new headquarter. Both in terms of costs and strategy, building a new
headquarter proved to be the best alternative.
The integrated overall energy design of the Power Tower
consists of three pillars:
building shell/façade – building technology – energy generation. Altogether, the new corporate headquarter saves
about 450 tons of CO2 emissions per year, as compared to
a conventional high-rise building. It thus actively contributes to the protection of our climate.
The Energy System
Lighting
The energy is obtained from the soil and the ground
water and/or generated by the solar power station on
the façade of the office high rise.
A unique art project was also integrated into the façade
of the Power Tower. A total of almost 700 LED lighting
elements were installed, which create extraordinary
light effects. During normal operations, the illuminated
façade will create an unpretentious, but unmistakable
impact on the Linz skyline. As state-of-the-art lighting
technology is used, the light installation fully corresponds to the Group’s energy efficiency approach. The
artistic light installation uses a maximum of 1.4 kW,
which is less electricity than is consumed by a commercial vacuum cleaner. During normal operation, the light
installation will only be turned on for a few hours using
only eight intensity of the luminosity, so that neighbors
will not be affected by it.
The implementation of the system is a unique milestone
in company’s philosophy concerning energy efficiency
and sustainability.
Façade
Two thirds of the multi-functional façade design consists of glass, and one third is made of highly insulating
materials. The result is a low demand for heating,
as well as minimum cooling requirements. By fitting
innovative slated sunshades, the solar radiation can be
reduced by 90 per cent. It was therefore not necessary
to install a conventional air-conditioning system.
Ventilation
The technology used for the building creates a pleasant and wholesome atmosphere. Heating and cooling panels are suspended from the ceiling and offer
a pleasant indoor climate with their radiation effect,
without causing any air currents. A controlled ventilation system supplies fresh air. The change of air in the
offices does not cause any noise, is health-promoting
and cost-saving. There is no need to use conventional
air conditioning.
Solar Power Station
With its surface of about 650 square meters, the solar
power station on the south-west façade of the Power Tower is one of the biggest solar power plants in
Austria that are integrated into a building façade. The
plant produces about 42,000 kWh of electricity per year
and supplies the ecological fraction to the electricity
demand of the office building.