CTO Assessment - European Commission

PAUL LOEBE HAUS
Sustainable Energy
Public Building
Contact: Johannes Hanf • Braunfels Architekten
D-10969 Berlin • Germany • Tel: +49 30 2537 600
Email: j.hanf@braunfels-architekten.de
One of the major buildings erected in the
governmental quarter of Berlin during the
last years was the Paul Löbe Haus that
houses offices of the federal elected officials
as well as the meeting halls of the Federal
Lower House of Parliament Committee.
The Paul Löbe Haus is a subtle mixture
of PV integration and combined heat and
power plants, accompanied by the target to
reach the energy standard of at least 25%
better than the actual building regulations.
This PV system is the world’s largest thinlayer
system integrated into a building made
of amorphous silicon, the world largest system
made of semi-transparent PV modules,
and one of the largest directed shadow photovoltaic
systems in existence.
Main motivations
During the 1990’s, Berlin has taken the
opportunity of the move of the headquarters
of the German capital from Bonn to
Berlin to adopt a program of implementation
of RE technologies into the various
public buildings that needed to be erected in
the new governmental quarter in Berlin. The
environmental energy strategy «Solar supplied
governmental quarter» targeted at the
integration of circa 1 MWp of photovoltaic
systems into the governmental buildings. As
well, plans were to provide low energy buildings,
to avoid air-conditioning systems and
to use combined heat and power plants on
the basis of biofuels (rape-oil) for energy
supply.
The Project
The «Paul-Löbe Haus» is a building of about
950 offices for members of the Parliament,
21 conference halls for Parliamentary Committees
and meeting rooms, a seminar area,
two restaurants, the Europe conference hall
and a visitors area. A 123 kWp solar plant
is integrated in the lamella shading system
for the central atrium.
A decentralised renewable energy system
has been built up between the governmental
buildings in the Spreebogen, the governmental
quarter. The buildings are interconnected
with a local electricity grid, as well as with
two central seasonal aquifer-storages, one
for cooling and one for heat situated below
the Reichstag building. Combined heat and
power plants (CHP –units) are also a major
power supply of this local energy system.
As a result 80% of the consumed thermal
and electric energy of all governmental
buildings in the area are provided with RE.
Overall Evaluation
The integration of a photovoltaic system
however arrived in a later stage of the several
years project implementation to replace
the originally planned aluminium blinds as
a heating system concept. The positioning
of the PV panels was not optimal in terms
of electricity production, but the PV-system
offered other energy benefits, such as the
possibility to use daylight from the north,
without blurring effects, and reducing overheating
in the building.
Hence, despite the fact that certain climatic/
sun conditions cause a contradiction between
optimising the lamella shading system
for daylighting and maximal solar energy
gain of the PV-system, the solution was
to run the system energy optimised in terms
of the overall energy consumption.
Solar
governmental
programme
PV in the Paul
Löbe Haus
Combined heat
and power plants
Energy standard
in the
Paul Löbe Haus
Main innovative aspects
The main innovative aspects are technical,
and certainly demonstrated the importance
of considering the multi-functionality of PV
systems. For instance, in the wintertime,
especially in the afternoon, it is more energy
efficient to use all sunlight for
daylighting, than using it for producing solar
electricity, in which case lamellas can be
moved to minimise shading of the hall.
Challenges
Berlin took the opportunity to become the
demonstration ground for ambitious architectural
projects over the last decade: the
Spreebogen is a symbolic historical area,
containing the Reichstag, and close to the
path of the Berlin wall, thus making it a
powerful centre for innovative architectural
projects. On the other hand, the very large
ground available imposed very little restriction
on architectural design. The only challenges
were therefore how to organise the
most optimal energy system among the different
new buildings.
Replication Potential
It is certainly an impressive achievement in
the field of architecture. The Paul Löbe
House demonstrated how a building based
on renewable energy can be combined with
aesthetic criteria and passive solar techniques.
Environmental strategy «Solar supplied governmental
quarter» with the objective to have circa 1 MWp of
photovoltaic systems into the governmental buildings
123 kWp solar plant, 6,048 semitransparent PV lamellas
were installed on the 5,500 m 2 roof made of saw-tooth glass
World’s largest thin-layer system integrated into a building
made of amorphous silicon
Multi-functionality of PV systems: electricity, but also for
passive solar house purposes
Biofuels (rape-oil) energy supply; 80% of the consumed
thermal and electric energy of all govermental buildings in
the area are provided with RE
At least 25% better than the actual building regulations
80% of the consumed thermal and electric energy of all
govermental buildings in the area are provided by RE
52 CTO - Showcase