4.1 General information

Kollektivhuset is a building for disabled people, and located close to one of the busiest roads to the centre of Copenhagen. The building works along the principle of commune living, with mutual services in the lower floors. In this project, 12 kWp have been installed as part of a fagade renovation. The renovation of the open balconies to glazed balconies with integrated PV-systems, have dramatically improved the comfort and reduced the energy consumption of the building. This specific building has a panoramic view and is a good example of buildings from the early 70’s. Kollektivhuset is a valuable building, worth the effort of remodelling and improving. With its location the project can be expected to be one of the most visible and well-known PV projects of Copenhagen.

The main objective of the demonstration project Kollektivhuset is to demonstrate how BIPV can be utilised in a fagade renovation of a housing block. The principle is that PV-modules are fully integrated in the new glazed balconies of the building, allowing the possibility to individually expand the PV-modules to cover the whole parapet area of the fagade

Kollektivhuset, Hans Knudsens Plads Copenhagen, Denmark.

4.2 Innovative BIPV Architecture

The renovation of the building was initiated in order to extend the lifetime of the open concrete balconies and at the same time enlarge the balconies to allow access by wheel chairs. By glazing the balconies the heavy traffic noise problems from the main road can be reduced significantly.

The new concept developed within the project focuses on the integration of 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 by the PV-modules.

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 the tenants. The solar cell installations in effect work as radiators for the balconies. The moveable back-plates invented 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.

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. The PV modules are laminated directly to the back of the parapet glass. The flexible sliding back-plate moves in the same mounting profile as the glass. Hereby the users of each dwelling can decide whether or not utilise the solar heating, which builds 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 (top picture). Hereby the heat will be forced to leave the parapet-zone through the ventilation slits 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

(middle picture). In this position, the PV-panel will radiate heat to the balcony. In the spring and fall, the heat from the solar cells can thus extend the possibilities to use the balcony.

PV-module with open regulator — spring / fall.

The system is prepared for the addition of another solar module in each balcony. The current economy only allowed for one module per balcony. In order to use the sun to maximum effect, the modules are put to the left on the balcony (as seen from the outside,
bottom picture), where they avoid shading from the structure.

The solar cell aesthetics are worked through thoroughly, especially when it comes to semi­transparency, effects of layers and so on. Mono-crystalline cells were chosen for the beauty of their deep-blue colour. The glass fapade on the balcony lets light through to the inside. A low opaque part (the hand-rail, approximately 70 cm) gives a sense of safety, while still giving the opportunity to look down from a sitting position (which is important for handicapped tenants). An interesting, deliberate effect is that the moving of the regulators will create a living, dynamic fapade. This brings the spark of life to a strict building.

4.3 Innovative electrical connections

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. In order to provide more flexibility in the future expansion of the system, the approach is different in this project. 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.

4.4 Energy and environmental performance

Through the carefully designed PV-system an

electrical yield of approximately 85 kWh/sqm 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
including environmental taxes and VAT. The installation costs were approximately 11.2 Euro per Wp. This amount must be seen in connection with the high degree of flexibility and large potential of replication.

4.5 Kollektivhuset in summary

Kollektivhuset is a very visible housing block located at the Hans Knudsen Square. 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.

2. Conclusions

PV-NORD is the first step towards the widespread exploitation of building integrated photovoltaics in the Northern Dimension of the European Union. All the building owners, construction companies, PV manufacturers and designers involved in PV-NORD believe BIPV to be an important area of work for the future energy supply for society. It is clear from the early results, that the cost of the solar modules still is too high for BIPV to be a realistic alternative in the open market. It is also clear that the added values, inherent in BIPV, can be a feature better utilized for the increased use of BIPV, as shown by the Kollektivhuset building. The use of BIPV in high-profile buildings requires financial support. Limits, imposed by the authorities, on the design values of the energy use in the buildings are supportive incentives.