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Office and factory building in Bielefeld – energy self-sufficient thanks to geothermal heat

The cube-shaped office building with its modern forms and colours is a striking symbol for the company owned by the brothers Michael and Udo Heiler.

While the ground floor and 1st upper floor received an anthracite façade, the two top floors seem to shine with their orange-red metal cladding. The west side of the office building is adjoined by an angled hall complex. The goal of the planners and building owner was a highly ecological new building with a compact construction, high-quality design and low energy consumption covered by renewable energy sources.

The energy concept is based on two components. Two geothermal heat pumps, each with a power output of up to 30 kW, provide the necessary heat supply. Connected to ten probes with a depth of up to 98 metres, the thermal energy is buffered into a 2,000 litre multi-function tank. If this output should prove insufficient at especially low outdoor temperatures a 66 kW gas condensing unit automatically switches on as a peak load boiler.

The photovoltaic component, which is installed as an elevated system with a total output of 133 kWp on the green roofs of the halls, makes the new heiler building virtually energy self-sufficient. However, the rooftop greening also fulfils other functions. It not only compensates for the sealed areas resulting from the building and surrounding paved areas, but also helps to cool the PV modules in order to maintain stable efficiency also in the summer months.

Facts and figures

Construction sign
Designation, name of project:Office and factory building
Location:Bokelstraße 1
33649 Bielefeld-Ummeln
Key figures – Area:2.250 m² floor area
3,500 m² heated area
Key figures – Technology:Energy performance values:
HT (for zones >19°C) 0.70 W/(m²K)
HT (for zones <19°C) 0.61 W/(m²K)
Key figures – Energy concept:
  • Heating: brine/water heat pump; condensing boiler for coverage of peak load
  • Heat distribution/delivery: dual-pipe network, panel heating as in-floor heating
  • Cooling: free cooling via the brine of the geothermal heat pump
  • Ventilation system: controlled residential ventilation with heating function in the office and recreation areas
  • Hot water: Electric continuous-flow water heater
  • Electricity: photovoltaic system with 133 kWp total output
Vaillant products:Geothermal heat pumps of type “geoTHERM” each with up to 30 kW power output in combination with 2,000 l multi-function tank, gas condensing unit “ecoTEC exclusiv” with 66 kW output
Building owner:heiler GmbH & Co KG
Sports field construction & landscaping,
33649 Bielefeld-Ummeln
Architect:Dipl.-Ing. Interior Designer Beate Werning and Dipl.-Designer Michael Seppmann, 32051 Herford
Facilities planner:
General contractor Goldbeck Bau
GOLDBECK GmbH, 33649 Bielefeld
Pictorial material
Photos and drawings:Joachim Stretz and GOLDBECK GmbH