General information
Kollektivhuset is a building for disabled people located close to one of the
most trafficated roads to the center of Copenhagen. The renovation of the
current open balconies to glazed balconies with integrated PV-systems, will
dramatically improve the comfort and reduce energy consumption of the building.
With its location the project can be expected to be one of the most visible and
well-known PV projects of Copenhagen.
Architecture
The house is a typical concrete-element high-rise block in 11-storeys and was constructed in
the late 50's.
The facade facing west and by that the heavily trafficked approach road, has until recently
consisted of open balconies which were of repetitive character.
DOMUS arkitekter a/s has been in charge of renovating the balconies and the development
of design concerning the balconies which by enlargement and glass covering have been
made more comfortable and approachable, allowing access to the wheel-chairs which many
of the occupants use.
Solar cells have been placed in the new facade of glass. They can produce both heat and
electricity. The solar cells were designed in light of different parameters. For instance the
density, the visual expression from both in-and outside, and the light passing through.
Today, the front of the facade has a much more varied expression. Reflections and open
glass-parts are the first couple of things one notices.
Secondly - a composition of colored glass behind the solar cell panels which provides an
image of daily use of the balconies.
Passing the building often,one would further-more experience how the vertical or horizontal
elements of the facade become noticeable depending on the changing seasons and light.
Objective
The main objective of the demonstration project Kollektivhuset, is to
demonstrate how a facade renovation of a housing block can be done in such a way,
that PV-modules can be fully integrated in the new glazed balconies of the
building, providing possibility to individually expand the whole area of
PV-modules in the facade. The new concept to be developed within the project
focus on an integration between the climate envelope of the building and
individually AC-modules. The new facade profile system allows for opening of the
windows in the glazed balcony and in the parapet of the balcony, a flexible
system for individually sliding back-plates behind the PV-modules are installed
to provide flexible utilisation of the heat generated on the PV-modules.
Innovative approach
The front glass of the parapet is a normal glazed balcony glazing, ensuring
water tightness and sound protection from the main road in front of the building.
Behind this glazing the PV-modules are placed and in this zone also a flexible
sliding back-plate system is integrated. Hereby the users of each dwelling can
decide whether or not utilise the solar heating building up on the PV-panel. In
the summer case, the users will be most interested in ventilating the heat from
the PV-panels to the outside. This is done by sliding the moveable back-panel in
a position just behind the PV-panel. Hereby the heat will be forced to leave the
parapet-zone through the ventilation openings at the top and bottom of the
PV-panel. In case the user wants to have the heat to enter the glazed balcony,
the back plate is moved to the side. Hereby will be the PV-panel directly heat
the air on the balcony and radiate the heat to the balcon.
Main benefits of new concept
Mostly disabled tenants are occupying the house, many in wheel chairs, and an ordinary
installation of PV-panels in the parapet would have radiated a large fraction of heat directly to
the legs of wheelchair-users. The moveable back-plates introduced here, provide a flexible way
of controlling this heat emission from the panels and even support the controlled airflow around
the panel in order to remove the excess heat.Hereby a dynamical control of the heat emission is
provided without the use of advanced ductwork for ventilation air,with cleaning and regular
maintenance needs. Furthermore the heat building up on all building integrated solutions
especially in summertime will efficiently be ventilated to the exterior, hereby keeping the solar
cells cooled to maximise the electrical efficiency .
In ordinary projects the electrical wiring of the systems would be based on string wiring, where
each floor of the building would be connected to one string inverter. The approach in the
present project is different: In order to provide more flexibility in the future expansion of the
system.The string wiring is established in vertical zones fully integrated in the facade
construction collecting the power from each panel. All electrical connections are based on the
Multicontact ® PV--cables, which allow the connectors to be accessed directly at each balcony
without any risk of electrical shocks. The sliding system of the panels described above is
designed so that further panels can be inserted at each balcony and directly connected to the
string-wiring, allowing flexible expansion of the system.
Furthermore the installation is also very easy to carry out, since all manual installation work and
expansion of the system can be done from the balcony and does not require expensive
scaffolding of the building. Hereby the relative installation costs of the system will be relatively
low compared to traditional installations of PV in high-rise buildings.
Energetic and environmental performance
Through the carefully designed PV-system an electrical yield of approx.85 kWh/m2 active solar
panel is expected from the system. Due to the net-metering possibility in Denmark, the value of
the power produced will be equal to the amount the tenants would have paid for the electricity
incl. environmental taxes and VAT. In other words the selling price for the electricity produced by
the system has the same value as electricity purchased by the tenants, and principally the
electricity grid served as short-and longtime storage of the power produced.
Budget and financing
The renovation of the building was initiated in order to extend the life-time of the concrete open
balconies and at the same time enlarge the balconies to allow for wheel chair access. By
glazing the balconies the heavy traffic noise problems from the main road can be solved. The decision to integrate PV in the parapets of the glazed balconies was taken during 2000, and by receiving support from the European Union the necessary finance was provided for developing
this new concept of PV-integration for European wide replication. The anticipated installation
costs has been approx.11,2 Euro per Wp. This must be seen in connection with the high
degree of flexibility and large potential of replication.
Partners
The architectural company Domus carrying out the design, are among the leading specialists in
architectural integration of PV in Denmark,and has in a number of projects been involved in PV-design and in more general dissemination of building integrated PV solutions for the Danish
building Stock. The engineering counterpart, Esbensen Consulting Engineers, has been active in
the field of energy conscious building design for more than 20 years, and holds a position as
the national representative of Denmark in the IEA PVPS Task7 on Integration of Photovoltaics in
the Built Environment. Also a very fruitful collaboration with the manufacturer of the system, Gaia
Solar A/S, has been established and large parts of the electrical detailed design has been
suggested and implemented by Gaia Solar.
Contribution to PV-NORD project
Kollektivhuset is an important demonstration project in Europe to show new
ways of flexible integration of PV systems in housing blocks, where the
extension in the future can be done individually. The strategy behind the
building will be valuable to the other partners and projects. Especially the
optimisation process to achieve maximun energy output of the system and the
analysis of potential risk of glare effects from Sunlight being mirrored in the
glass facade.
Kollektivhuset is a one of the most visible housing blocks located just at the
Hans Knudsen Square, where more than 30.000 citizens of Copenhagen pass the
building during rush hours. The facade of the building is likely to be one of
the most visible and well-known demonstration projects with building integrated
photovoltaic systems in Denmark. The individual wiring of the PV-panels, and
combination of sliding back-panels and fixed front glazing is a unique concept
in Europe. It is very likely, that the system will mark a new standard for
providing PV to Scandinavian housing block tradition, where the tenants can be
expected to have individual priorities and possibilities to further expanding
their solar system.
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