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House on the lake in Kalkar

The pilot project “Living with Vision” is a 120 square metre research building with plus-energy standards that originated in 2011.

The cube-shaped building, which floats on pontoons, plays a vanguard role with respect to energy efficiency and innovative housing development.

The initial housing concept was developed by the architects Hülsmann & Thieme. In view of the fact that spatial resources in many cities are exhausted, the gravel pit provided an eco-friendly alternative for building one- to two-storey structures. The one-storey pilot building was erected on a steel pontoon as a timber stud construction; additional buildings are planned. Designed as a floating research station, the cube-shaped building is used for simulating and analysing the life of a family of four. To adapt the construction to the energy requirements, the building shell was optimised so that the required heat was reduced to less than 14 kWh/m2a. This requirement is supplied by a geoTHERM plus brine/water heat pump from Vaillant that is modified for an output of 3 kW. The system is supplied by a thermal basket in the lake, which functions just like a heat exchanger. A 500 litre multi-function tank buffers the heat and supplies the hot water and drinking water. The downstream heat distribution is achieved by a surface heating system and special heat pump elements.

In the summer the heating circuit of the heat pump is automatically bypassed and passive cooling is started. The thermal basket then diverts the excess heat directly into the lake water. The energy concept is supported by three photovoltaic systems for power generation: PV modules on the roof, collectors that automatically follow the movement of the sun as well as vertically installed modules for utilisation of the light reflected from the water.

Facts and figures

Construction sign
Designation, name of project:House on the lake in Kalkar
Typology:Single-family house
Location:Birgelfeld gravel pit lake in Kalkar-Hönnepel
Key figures – Area:120 m²
Key figures – Technology:14 kWh/m²a heating energy
Key figures – Energy concept:
  • geoTHERM plus brine/water heat pump with 3 kW
  • Use of heat from the lake water via thermal basket
  • 500 l multi-function tank
  • Heat distribution via a surface heating system and special heat pump elements
  • Photovoltaic systems on 40 m² for self-sufficient power supply
Vaillant products:
  • geoTHERM plus brine/water heat pump
  • 500 l multi-function tank
Building owner:Kieswerk Maas-Roeloffs GmbH & Co. KG
47546 Kalkar / DE
Architects:Architekturbüro Hülsmann & Thieme
47533 Kleve / DE
Facilities planner:BASCON Engineering GmbH
47574 Goch / DE
License information
Plan material & source:Architekturbüro Hülsmann & Thieme