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Projektinfo 04/2011

Buildings of the future successful in decathlonGerman University teams present their energy-plus buildings at Solar Decathlon Europe

In June 2010, the Solar Decathlon Europe took place for the first time in Madrid. The aim of the international competition is to develop and independently build experimental and cutting edge homes. In terms of their annual energy balance, the buildings must cover their energy needs by using solar power. During the eight-day competition, judging panels assessed the buildings in ten individual disciplines. In Madrid, the University of Virginia from the USA successfully beat off 16 competitors to achieve first place. Two university teams from Germany also made it onto the winning rostrum.

The Solar Decathlon, which is based on the American version of the competition, was brought to Europe for the first time by the Spanish Ministry of Housing and Universidad Politécnica de Madrid. An agreement with the US Department of Energy made this possible. The international competition enables students in interdisciplinary teams to already turn theoretical designs into practice during their studies. In addition, the organisers want to raise awareness among the general public about the need to take a responsible approach to using energy and demonstrate that comfortable living and energy efficiency can coexist in harmony.At the first Solar Decathlon Europe, 17 student groups from different universities presented their buildings of the future. These included four German university teams, supported by many external planning, industry and research partners. All participating teams constructed their buildings within just a few days on the open space at the Villa Solar on the Rio Manzanares. The results are very impressive. The students from Rosenheim achieved second place, just behind the winners from the USA and ahead of Stuttgart, which came in third. The teams from Wuppertal and Berlin were respectively ranked 6th and 10th.

This research project is funded by the:

Federal Ministry of Economics and Technology (BMWi)

BINE-Projektinfo 04/2011

Assessment criteriaThe prototypes fulfil all the functions of a home for two people. Up to eight people should be able to eat in the dining area. A uniform geometric frame stipulates the maximum floor area and height of each building. Further provisions relate to the energy supply and the indoor comfort. The homes represent a special form of energy-plus buildings, as only solar energy is permitted as the energy source. These are “electricity-only” buildings, whose electrical energy requirements across the course of the year are balanced out with a grid-connected PV system. It is desired that a large proportion of the electricity requirements are directly met by solar power without passing through the electricity grid.Based on subjective assessments (e.g. Architecture, Inno-vation and Sustainability) and objective measurement values (e.g. Electrical Energy Balance and Comfort Condi-tions), several judging panels award up to 1,000 points in ten disciplines, hence the name Solar Decathlon.

The German entriesAll german concepts are based on optimum thermal insulation by means of a very well-insulated building envelope and consistent sun protection. In Madrid, alongside passive elements for indoor temperature control such as phase change materials (PCM), the use of active systems is essential in order to guarantee a pleasant indoor environment in summer (max. indoor temperature 25 °C). Each building has a ventilation system with heat recovery and a reversible heat pump.

Rosenheim: Zigzagging solar protectionThe Rosenheim students opted for a modular construc-tion system. This enables complete areas, including the interior fittings, to be prefabricated. The flexible floor plan enables optimum and multifunctional use of the spaces. For example, the kitchen block contains all the important functions for a kitchen in a minimum space along with an extendable dining table, lowerable flat-screen TV and cupboards. The facade consists of two envelopes: the inner glass and wall surfaces that provide the thermal skin and the external, newly developed folding screen that provides privacy and solar shading. This zigzagging protection is the defining feature of the building. The screen, which is made of white, powder-coated aluminium, can be folded flat below the building or continuously extended upwards. Depending on the time of day and the height of the sun, this creates an interesting play of light for both residents and passers-by. The students have constructed an energy-plus building that combines high living comfort with maximum energy savings. The building is predominantly cooled using passive measures. During the night, the PV modules can be cooled with water. The night-time radiant cooling enables the temperature of the water to drop below the air temperature. The cooled water is collected and sup-ports the indoor cooling during the day. A PCM buffer, through which air is channelled, absorbs excess heat during the day and releases it again at night. Monocrys-talline PV cells supply the electricity. The team won first place in the “Electrical Energy Balance”, “Usage” and “Comfort Conditions” categories. The building is being relocated to the “zero-energy town” Bad Aibling, where it will provide additional accommodation for a nearby hotel.

Stuttgart: Arabian-style energy towerThe compact building designed by the Stuttgart students consists of opaque modular sections arranged at intervals in a row. The resulting intervening spaces are used to provide lighting, natural ventilation, pre-heating in winter and passive cooling in summer. The size of the spaces can be adjusted in accordance with the location, making it possible to increase the light yields and passive solar gains. Solar cells in bronze and gold colours define the external appearance on the east and west facades. Together with the mono- and polycrystalline PV cells on the roof, they provide sufficient electricity. One special feature is the “energy tower”, which, inspired by the wind towers used in the Arab world, uses the principle of evaporative cooling. Cotton cloth hung inside the tower is moistened. The air flowing through therefore cools down and flows out at its base into the interior space. The exhaust air leaves the building through flaps in the roof positioned to the side of the energy tower. The thermal lift is improved through using small absorber sur-

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Fig. 1 Rosenheim building with closed and opened solar shading. Photo: Team Rosenheim, Oliver Pausch

Living space: 60 m2

Mean U-value: 0.14 W/m2KPV output: 13 kW

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HW: heat pump

Fig. 2 The Stuttgart building using modular construction. Photo: Team Stuttgart, Jan Cremers

Living space: 48 m2

Mean U-value: 0.2 W/m2KPV output: 12 kW

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HW: 6.6 m2 of evacuated tube collectors

Fig. 3 The solar walls at the Wuppertal building with the large adjoining terrace. Photo: Peter Keil, Düsseldorf

Living space: 48.5 m2Mean U-value: 0.14 W/m2KPV output: 10.2 kW

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HW: 6.6 m2 of evacuated tube collectors

BINE-Projektinfo 04/2011

faces that hang in the tower like mobiles. As a design element, the energy tower helps to visualise the energy concept for users. The building services equipment, in combination with the PCM in the ceiling, ensures a pleasant indoor environment. Water-carrying pipes in the ceiling support the cooling. A closed water circuit on the roof surface behind the PV modules also enables water to be recooled through night-time radiant cooling. The team won first place in the categories “Innovation” and “Engineering & Construction”. The building has been rebuilt close to the university for the time being until a final location can be found for it.

Wuppertal: The European buildingThe building designed by the Wuppertal students achieves a neutral energy balance not just in Madrid but also in other European locations. The basic structure of the building consists of two staggered wall panels – the solar walls. Positioned between the two is the living space, which can be fully opened to the terraces on both sides by sliding back glass door elements.

Fig. 5 Energy balance of the German homes throughout the eight-day competition period in June 2010. Source: K. Voss

Fig. 6 Room temperatures during the first five days of the competition. Source: K. Voss

The defining element in the interior space is the Smart-Box, an accessible, two-storey furniture element with diverse functions that was developed and built by the students. This living tower, which is like a home in a home, can be adapted to the respective requirements. Individual elements such as the sofa bed, two work tables and cupboards can be folded or pulled out. At the top is a private “retreat” with sundeck area. The central building services elements are also contained in the box.The heating and cooling functions are provided by a compact ventilation unit with a heat pump, which is supplemented with an underfloor heating and cooling surface and an evaporative cooling system. The electricity requirements are met by a PV system integrated into the flat roof and in the southern solar wall. A light ceiling with LED lighting ensures homogenous lighting in the interior space. Movement sensors ensure that only those areas are lit where people are currently situated. A translucent curtain system provides the necessary solar protection and at the same time offers views outside. The concept ensured that the students won second place in the “Architecture” category and for its lightning concept (special prize). The building will be lived in at its new location in Wuppertal in order to investigate how it works under realistic conditions.

Berlin: Outside larch, inside loamThe Berlin team has combined cutting edge technology with traditional, central European construction based on timber and loam. Their driving principle was to achieve sustainable living without compromising in terms of comfort. The rainscreen facade and roof are clad in scorched larch wood, which gives the building its dark-coloured appearance. The students deliberate-ly avoided using high-tech materials. Two light bands, which are oriented towards the four cardinal points, split the building along its axes and il-luminate the interior space. They define the floor plan, the division of the internal spaces as well as the form and structure of the building envelope, while forming a contrast to the black envelope. The gable roof and facade are equipped with building-integrated PV modules and solar collectors for domestic water heating. The frame-less black modules are harmoniously integrated into the building and ensure the homogenous appearance of the overall envelope. Folding shutter doors made of photovoltaic modules, which were developed and built by the students and sponsors, ensure effective solar shading. The judges awarded the system 1st prize in the “Solar Systems and Hot Water” category.Heating, cooling and ventilation occur by means of a ventilation system with dehumidification. PCM in the loam walls and a natural night ventilation system ensure an excellent indoor environment. Cooling is actively supported by water-carrying pipes in the clay panels. During the night, the radiation surface on the north-facing roof enables this water to cool down by allowing the water to flow through capillary tube mats that are applied to its rear side. The building is being relocated to the Wilhelminenhof campus belonging to the Berlin University of Applied Sciences, where it will be used, amongst others, for research purposes.

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Rosenheim Stuttgart Wuppertal Berlin

kWh

Netzeinspeisung diverse Verbraucher Medien Beleuchtung

Haushaltsgeräte HLK & Warmwasser Netzstrombezug Solarstromertrag

Electricity fed into grid Diverse loadsMedia

Illumination Domestic appliances HVAC & hot water

Electricity drawn from gridElectricity sources:

Electricity consumption:

Solar electricity yield

19.06 20.06 21.06 22.06 23.06 24.06 25.06

Assessment period Rosenheim Stuttgart Wuppertal Berlin

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Fig. 4 The frameless PV modules are harmoniously integrated into the Berlin building. Photo: Team Berlin living EQUIA

Living space: 48 m2

Mean U-value: 0.14 W/m2KPV output: 5.7 kW

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HW: 8 m2 of flat-plate collectors

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Contact · InfoQuestions regarding this Projektinfo brochure? We will be pleased to help you:

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Project organisationFederal Ministry of Economics and Technology (BMWi) 11019 Berlin Germany

Project Management Organisation Jülich Research Centre Jülich Markus Kratz 52425 Jülich Germany

Project number 0327429B,C,D,E

ImprintISSN0937 - 8367

Herausgeber FIZ Karlsruhe · Leibniz Institute for Information InfrastructureHermann-von-Helmholtz-Platz 1 76344 Eggenstein-LeopoldshafenGermany

AuthorMicaela Münter

Cover imageTeam Berlin living EQUIA

CopyrightText and illustrations from this publication can only be used if permission has been granted by the BINE editorial team. We would be delighted to hear from you.

Tests in practice following the competition The competition is over but the work continues. The competition period of just a few days does not enable any conclusions to be drawn about the year-round functionality of the buildings. For this reason, the prototypes will continue to be tested and optimised at their future locations, and in Wuppertal under real living conditions.The results of the German competition entries have shown that the energy-based requirements specified by the competition can certainly be fulfilled (Fig. 6). Each team succeeded in generating considerably more than the required electricity surplus of 40 kWh. It was much more difficult, however, to maintain the comfort requirements in terms of temperature and humidity (Fig. 5). All teams had difficulties here in meeting the strict competition criteria. No points were awarded if the temperature deviated from the stipulated requirement by more than just 2 kelvins. With external temperatures of up to 36 °C, the buildings had to be cooled down within 60 minutes of the guided tours to the narrow temperature range of 23-25 °C. A high cooling performance therefore provided considerable advantages. Because of the less demanding energy requirements, the additional energy consumption was generally not a disadvantage. In addition to the measurable parameters, a convincing presentation of the concept to the judging panel was a substantial factor for a successful competition. The competition requirements are complex and hardly any participants had ever worked on a comparable project. For the students taking part, the Solar Decathlon therefore provides very good preparation for their future working lives.The next round of the Solar Decathlon Europe will take place in 2012. Madrid will once again be hosting the competition. Two German university teams are taking part and will be competing against 18 other student groups for the best energy-plus building. The Constance students have set themselves a very ambitious goal: they are planning to achieve an autonomous energy supply without having to forego any comforts. The students from Aachen are endeavouring to achieve an energy-, material- and transport-efficient building. In addition to the high degree of prefabrication, low construction costs are another important aspect. The German Federal Ministry of Economics and Technology has once again been asked to act as patron for the German competitors. All building types rely on new technologies that have already been developed and tested to a large degree as part of the EnOB research initiative with the aim of developing climate-neutral zero-energy buildings that will become the standard in future.

BINE-Projektinfo 04/2011

Project addresses b German participants in the Solar Decathlon Europe 2010: Rosenheim University of Applied Sciences, Marcus Wehner,

www.solar-decathlon.fh-rosenheim.de Stuttgart University of Applied Sciences, Prof. Dr.-Ing. Jan Cremers, www.sdeurope.de University of Wuppertal, Prof. Anett-Maud Joppien, Prof. Dr.-Ing. Karsten Voss, www.sdeurope.uni-wuppertal.de Berlin University of Applied Sciences, Arlett Ruhtz, www.living-equia.com

Literature and Internetb Literature (in German): Leitte, S. (Red.); Strobl, C. (Red.) : SolarArchitektur4. Die deutschen

Beiträge zum Solar Decathlon Europe 2010. München: Red. DETAIL Institut für internationale Architektur-Dokumentation GmbH & Co. KG, 2011. 176 S., 1. Aufl., ISBN 978-3-920034-48-5, 35,90 Euro. Detail green books

Voss, K.; Musall, E. (Hrsg.): Nullenergiegebäude – Klimaneutrales Wohnen und Arbeiten im internationalen Vergleich. München : Red. DETAIL Institut für internationale Architektur- Dokumentation GmbH & Co. KG. [geplant für Mai 2011]

b Internet: www.enob.info | www.enob.info/de/solar-decathlon-europe-2010

www.sdeurope.org | www.solardecathlon.gov

More from BINE Information Serviceb This Projektinfo brochure is available as an online document at www.bine.info under

Publications/Projektinfos. Additional information in German, such as other project addresses and links, can be found under “Service”.

b BINE Information Service reports about energy research projects in its brochure series and newsletter. You can subscribe to these free of charge at www.bine.info/abo.