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Community-run solar housing estate

The solar housing estate in Bielefeld Kupferheide is the first in North Rhine-Westphalia’s programme “50 solar housing estates in NRW” to have a local heating network run collectively by the individual private owners. The municipal administration has also obligated them to comply with ambitious energy-saving standards in the construction of the houses.

Bielefeld’s city council is the first in NRW to have developed, together with many different house builders, an ambitious energy plan for an entire housing estate supplied by solar power and heat. To be able to realise the ambitious goals, the city, together with the individual stakeholders, stipulated a joint plan complete with energy-saving standards. The estate in Bielefeld is part of the state-based project “50 solar housing estates in NRW”, developed by EnergieAgentur.NRW, which offers wide-ranging support to the local energy sector on behalf of North Rhine-Westphalia’s state government. With a total of 66 homes, the Bielefeld example demonstrates ways in which solar energy can be used to supply heat and power. 

Engine for progress:

  • estate saves 140 tonnes of CO2 each year
  • 32 properties built according to the low-energy house standard
  • 14 buildings constructed as 3-litre houses
  • 312 square metres of solar collectors
  • local heating network is operated independently

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Photo: Rainer Friedrich

Bielefeld’s city council is the first in NRW to have developed, together with many different house builders, an ambitious energy plan for an entire housing estate. The first challenge was for the city to accommodate the house builders’ various preferences.



Community-based local heating network

At the Kupferheide solar housing estate, the city set great store on a decentralised heating system. The individual houses are connected by a local heating network, which is supplied with heat from solar thermal energy and a gas-fired boiler. Over 60 per cent of the hot water supply is produced by solar collectors with a total surface area of 312 square metres. The local heating network is designed so that all of the buildings can feed in and retrieve excess thermal energy. That is why it was particularly important for all of the property owners to become part of the network. To ensure that this happens, the city council has contractually bound all of the parties into an owners’ association. The purpose of the association is to run the local heating network. This includes the care and maintenance of parts of the system, such as the gas-fired boiler, solar collectors and distribution grid. 

Overall scheme saves 140 tonnes of CO2 annually

In comparison with conventional buildings, the houses on the estate save around 300,000 kilowatt-hours of heat each year. Photovoltaics with a capacity of approximately 73 kilowatts have been installed on the roofs and generate around one third of the power required by the estate. Because gas is used for cooking, and priority is given to consuming the solar power produced on the roofs, around 100,000 kilowatt-hours less electricity is bought in each year. In total, approximately 140 tonnes of CO2 are saved on the estate annually as a result of the arrangements in place for power and heating.

High-quality construction 

There are 46 buildings in total on the solar housing estate. In the first phase of construction, 31 semi-detached properties and one apartment building were built according to the low-energy house standard in conformity with German Thermal Insulation Ordinance 1995 (WSchV 95). The heating demand was around 52 kilowatt-hours per square metre per year – a good 25 per cent under the figure then required by WSchV 95. In the second phase of construction, 14 terraced and semi-detached houses were built according to the “3-litre house” standard. Their heating demand is only 30 kilowatt-hours per square metre per year. 


Photo: Peter Wehowsky

“Carrying out independent, three-stage quality assurance has contributed to the high quality and energy efficiency of the buildings. Each of the individually-planned buildings was subject to a calculation review, multiple site visits and a measurement of its airtightness.”

Rainer Friedrich, head of Bielefeld city building authority’s building consultancy unit 



Partners and sponsors


Partners:
  • Stadt Bielefeld
  • Institut für Kommunal- und Umweltplanung
  • Stadtwerke Bielefeld
Sponsors:
  • Ministerium für Klimaschutz, Umwelt, Landwirtschaft, Natur- und Verbraucherschutz (MKULNV)
  • Ministerium für Bauen, Wohnen, Stadtentwicklung und Verkehr (MBWSV)
Counselling centers:
  • EnergieAgentur.NRW