02 July 2019 | updated: 27.10.2021

The international competition Solar Decathlon Europe 2021 (SDE21) in Wuppertal, Germany, will give students the opportunity not just to present their innovative and energy-efficient solar building designs on paper but also to build and operate prototypes. We spoke to Professor Karsten Voss from the University of Wuppertal about why the urban aspect plays such a central role in this competition and what challenge the students will face.


Professor Voss, of students’ timetables and those of teachers are already full. Why should they still apply to compete in SDE21?

I can speak from my own experience here because the University of Wuppertal itself took part in the competition in 2010 in Madrid. Although it’s true that participating involves a lot of work, the Solar Decathlon has a lot of advantages. For professors – particularly of architecture – it can be motivating to create a higher profile and to boost applied research at their own faculty. Furthermore, the Solar Decathlon positively affects the university beyond the competition. It impacts on interdisciplinary and inter-faculty collaboration: to mention just two examples from my own experience, this collaboration could be between architecture and economics faculties when it comes to market potentials, or architecture and electrical engineering faculties jointly working on building–grid interaction. Furthermore, the prototypes developed can afterwards be used for further research, for example for measurements or user surveys. In any case, SDE21 is a good example of how applied research can be implemented. If done the right way, it can lead to positive impetus.


Since 2010, the European version of the Solar Decathlon has taken place in Spain, France, and Hungary. What will be unique about the German competition location of Wuppertal in 2021?

Firstly, there has never been an SDE in Germany. For this reason alone, it made sense to apply. The decisive feature of SDE21, however, is the focus on solar building in the urban context because this accurately reflects the main issues of the transformation of the energy sector and of climate change in terms of the building sector. It’s not just about hip “tiny houses” but also about issues relevant to existing buildings and neighbourhoods. The SDE21 profile is not just about energy-efficient, solar building, it’s definitely about energy-efficient, solar building in the urban context. For the competition, this profile means that it’s about more than individual houses or gap sites. Building situations are becoming more complex: a house and surrounding area, another building that can be extended to build new buildings, or a neighbouring property we can build across... We are currently creating the basics for these situations. The first documentation will become available in July. Alternatively, participating teams can also present solutions for comparable situations from home. The prerequisite, however, is that the situations must be urban and address continued building in the existing context.


A jury of international experts evaluates the applicants’ proposals according to various criteria. These include urban mobility as well as communication and social awareness What is meant here?

Mobility was often secondary at past Solar Decathlon competitions. Sometimes, an electric car would be parked next to the house, but the mobility aspect was not really integrated in the concept. Essentially, sustainable urban mobility combines public transport with the use of partly electrically driven small vehicles. For us, urban mobility begins with the building design and its neighbourhood context. On the one hand, we want to see concepts from the teams in which public and private transport complement each other. We want to organize a competition here that goes beyond the evaluation of the concepts by the jury. The teams will be expected to use small electric vehicles to go shopping and for other tasks. Their energy consumption will be included in the evaluation of the energy performance. Furthermore, the teams will evaluate other teams’ houses in terms of user friendliness. It may also be an option to invite those living in the Wuppertal neighbourhood and have them evaluate the houses. These are ideas that are relevant to the field of communication and social awareness. When it comes to the topic of climate change, people should not only be confronted with storms and floods; they should also be presented with designs and solutions for a future worth living.


What role is played by civil society stakeholders during the Wuppertal SDE21?

Team Wuppertal, the organizers of the SDE21 competition, also includes the creative cluster Utopiastadt, who own the urban areas made available and are also involved in the conception of the project. Utopiastadt addresses “utopian” ideas for the city life of tomorrow and organizes citizen workshops, for example. The involvement of Utopiastadt in SDE21 demonstrates that ideas and solutions that arise from the competition appeal to civil society. We also have the unique opportunity in Wuppertal that 8 of the 18 houses to be built will remain standing after the competition. We are planning to use them to form a “Living Lab NRW”. Together with neighbouring universities and the competition teams, the houses will serve as a basis for further research. Utopiastadt also wants to turn the houses into a hostel. People could then simply stay there for a night – wouldn’t that be something special?

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