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Winterproof: an energy-plus building from the Solar Decathlon Europe is being put to the test in Wuppertal.
© Julius Otto, Bergische Universität Wuppertal
The energy-plus building put to the test

Measured annual energy balance: the orange line shows the rate of energy consumption and generation over the course of the year. The green line shows the import and export of power from the public grid.
© btga, Bergische Universität Wuppertal

Living to support energy research

The Solar Decathlon Europe is a competition for homes which cover their annual energy needs using solar power. Within the framework of an exhibition, they are evaluated over several days in operation. This short period of observation is hardly able to ascertain whether they are also able to meet the competition standards in everyday life. Now, a practical test in Wuppertal has provided sufficient evidence. Since the middle of last year, two people have been living in the house developed by the town´s university. The energy balance for 2012 is even. Subsequently, it is even anticipated that the house will produce surplus electricity.

The Solar Decathlon competition in Madrid in 2010 and 2012 generated a high level of interest among the media and general public. However, after the exhibition, the buildings presented tend to disappear from view. They are dismantled and returned to their countries of origin. The University of Wuppertal made it possible for this building to be used after the exhibition was over, and for the purpose originally intended, as a home for two people.

Solar building in the Wuppertal winter test

Since mid-2011, Julius Otto has been living with his girlfriend in the house, which came sixth in the competition. Otto was a member of the Solar Decathlon team from Wuppertal, and now works in the university’s architecture department, on behalf of which he has continued to evaluate the building. This is a self-test. “The house is built in exactly the same way as in Madrid. The only difference is that we’ve added a connection to the water mains”, says Otto. The fact that the building has to withstand different climate conditions in Germany than it does in Spain was taken into account in the design from the start.

Even so, the first winter has been difficult. The air tightness of the building envelope had suffered as a result of the multiple construction and dismantling procedures. In particular, damage to the large sliding doors led to cold temperatures indoors. Since in accordance with its design, the building only has one electricity connection, electric heaters had to be used, which had a dramatic effect on the energy balance. In the meantime, the problems have been resolved. Accordingly, consumption for the first few months of the new winter heating period has been lower. The photovoltaic system delivers the anticipated electricity yield. Overall, during the past year, as much power was generated as was consumed. After the power required for operating the measuring equipment was deducted, the house even managed to generate a surplus. Around a third of the self-produced solar power can be used directly on site, while the remainder is exchanged with the public grid (see diagram).

A single-room home: compact, but comfortable

However, it was not only the energy consumption which was tested, but also the extent to which the single-room house was suitable for everyday living. The large room, which is around 50 square metres in size, is dominated by a two-storey, walk-in piece of furniture. It holds the key technical equipment for the house, provides storage space and contains pull-out elements such as a sofabed and two desks. There is a sleeping area on the top. “The house is fully equipped, not only with furniture, but also with technical appliances. We have everything we need for everyday living. The single-room design also works well, as long as both inhabitants have a similar daily routine”, reports Otto. The couple had a lot of visitors over the last year. Around 1,500 people have taken a guided tour of the house to date.

The four German buildings from the 2010 competition are also being used as learning and teaching models in their current locations, and their measured data is being analysed. In 2010, the Solar Decathlon Europe took place for the first time in Madrid. During the competition, the jury judges the buildings in ten disciplines, such as architecture and electric energy balance. The next Solar Decathlon Europe will take place in 2014 in Versailles. 

BINE Projektinfo brochures on the competition

The BINE Projektinfo brochure “In competition for the best energy-plus building” (17/2012, currently in translation) reports on the two German participants in the Solar Decathlon Europe 2012, and on prospects for the future. The Projektinfo brochure “Buildings of the future successful in decathlon” (04/2011) presents the participants of the Solar Decathlon Europe 2010. For a report on the operation of the winning building by the TU Darmstadt at the Solar Decathlon 2007, see the Projektinfo brochure “International competition for solar living” (04/2010).



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