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Brine heat pump and photovoltaic system for retail and office buildings

Type: Non-residential building (new-build retail premises with offices)
Year of construction: 2022
Location: Bannewitz
Usable floor area: 1,238 m² (heated usable floor area, ground floor + first floor; separate heated storage area of 104 m², frost-free)
Installer / Designer: Haase Haustechnik, Meißen

following modernisation
  • Building heating load is around 74 kW
  • thermal output of the heat pump approx. 54 kW
  • Buffer tank (approx. 10 m³)
  • Heating energy requirement approx. 50 MWh/year
  • Cooling energy demand approx. 14.6 MWh/year
  • Specific heating demand per unit area approx. 40 kWh/m²a
  • PV yield (one system) approx. 55 MWh/a
  • Electricity purchased from the grid approx. 21.7 MWh/year
  • Electricity fed into the grid approx. 32 MWh/year
  • Electricity consumed on-site approx. 23.3 MWh/year
AI-generated: The image shows a DIY store building called "Mobau Müller" with a large car park. Various building materials and a landscaping area can be seen in the foreground.
© Hanitsch Fotografie
Geothermal heat pumpPhotovoltaics

Project description

T&K Invest GmbH developed a simulation-based energy supply concept for Mobau Müller Baustoffkontor GmbH in Bannewitz for the construction of a new modern retail and office building with a heated warehouse. The building comprises around 1,340 m² of usable floor area and was energy-optimised on the basis of a dynamic building simulation to ensure cost-effective and future-proof operation.

A particular challenge was posed by the limited electrical connection capacity of the 50-kW mains connections, which could not be upgraded. This must be sufficient to supply, across the entire site, four forklift trucks, a fresh concrete filling station, a paint mixing machine, servers, lighting for around 4,000 square metres, a ventilation system, as well as the building’s heating, cooling and hot water. The aim was to minimise the building’s energy requirements whilst simultaneously providing sufficient power for future charging infrastructure and operational loads.

At the heart of the energy concept is a brine-water heat pump with a ground-source heat collector covering an area of around 1,200 m². In conjunction with concrete core activation and underfloor heating, the system ensures an energy-efficient heat supply whilst also enabling passive building cooling in summer – without the need for any additional chiller. A ventilation system with over 80 per cent heat recovery further reduces heating energy requirements.

The concept is complemented by a 60 kWp photovoltaic system (with a 50 kW inverter), which generates around 66 MWh of solar power annually. This enables a large proportion of the electricity demand to be met directly on site, significantly reducing the amount of electricity drawn from the grid. Overall, the building has an annual heating energy requirement of around 50 MWh, whilst the heat pump requires only an electrical connected load of approximately 10 kW, despite a building heating load of around 74 kW. Compared with a comparable air-to-water heat pump, this represents a reduction in electrical connected load of around 45 per cent.

The result is a cost-effective and climate-friendly energy concept with low operating costs, high security of supply and optimal conditions for the integration of electric mobility as well as future expansions.