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Design sketch of the energy-plus building from Dresden
Energy-plus building supplies cars with electricity

Living in a power plant

Buildings of the future are secret power plants: they will generate more energy than they require. The surplus can be used for the residents’ electromobility or is fed into the grid. This idea is now to be implemented as an energy-plus building with electromobility. The fully recyclable house designed by scientists from Dresden, Germany offers 142 m² of floor space and produces more energy than is required for a 4-person household and to run two electric cars and an electric scooter (with an annual mileage of 29,000 km). The team of researchers from Dresden University of Technology won second prize at the planning competition of the Zukunft Bau (Future of Construction) research initiative with this pilot project in February 2011.

Externally, there are few differences between an energy-plus building and a conventional single family home, with a rectangular layout and a gable roof. No fossil fuels are used. The external shape of the building with the large sloped south-facing roof surface is the result of energy optimisation. The energy concept uses solar irradiation to produce electricity via photovoltaics, outdoor air as a source of heat for the heat pump and geothermal heat for pre-heating or pre-cooling the outdoor air.

Renewable energy produces an energy yield of 112% of the overall energy requirement. That not only makes the building autonomous in energy terms, it can even feed surplus electricity into the grid. Photovoltaic systems structure the facade and roof, while an enlarged and optimised south-facing roof surface combines traditional house designs and resource-saving energy production. The energy required to run the building and vehicles is covered by the PV system.

The key in developing the building was to maximise the integration of new technologies. Dipl.-Ing. Reinhard Mayer, the architect responsible for the project adds: “The focus of our design was to incorporate energy autonomy and electromobility as components of modern residential architecture into the overall architectural concept as part of the design.” The complex building services equipment is controlled via touch screens which facilitate an intuitive user-friendly interface.

From a study to a model house

The team of researchers is now working on making the concept marketable. Technical feasibility was the primary goal during the restricted competition period. Economic optimisation is now the aim. The modular energy-plus building can be adapted flexibly to changing requirements. With the objective of possible series production, negotiations are underway with manufacturers of prefabricated houses and vendors of PV modules. The cost of 960,000 Euros calculated for the pilot project could be reduced significantly in series production via price reductions and economies of scale for components. First the prototype must be implemented. “The need for comfortable but resource and energy-saving housing is more urgent than ever. We are in a process of global change, in which Germany has already taken on a pioneering role. Projects with mass appeal like the energy-plus building could make scientific planning utopia a reality,” according to project manager Prof. Clemens Felsmann of the Institute of Energy Technology at TU Dresden.

Assessment of the competition jury

The Zukunft Bau research initiative of the German Ministry of Transport, Building and Urban Affairs (BMVBS) evaluated the energy-plus building from Dresden as follows:
“The configuration of the volume was derived correctly from the solar irradiation and the associated maximisation of the south-facing surfaces. The arrangement of the PV modules is architecturally integrated and used to design the energy-plus building, which creates a noteworthy uniqueness via the black, frameless thin-film modules and the flush-mounted windows. The roof shapes and wall cladding can be varied according to the location and position – this makes the entry particularly valuable. The building shape is optimised for absorbing solar energy, while remaining compact.

The concept is based on a well-dimensioned energy yield of the PV systems combined with a 30 kWh buffer storage tank. This allows 53% of the electricity generated to be used internally. Integration of the user via touch screens, adaptive control options etc. offers a good combination of building services equipment and electromobility. However, the suitability of a mechanical ventilation system for a single-family home is considered questionable.”


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