Low temperature district heating and cooling

An innovative solution for municipal heat supply

The transformation from centralised fossil energy generation to decentralised renewable energies is one of the greatest challenges facing municipalities. low temperature district heating and cooling (LTDHC) offer a particularly efficient and forward-looking solution for neighbourhood supply.

Functionality

A cold local heating network is operated at the temperature level of the surrounding ground, typically between 5-15°C. The pipes are laid close to the surface and - unlike conventional heating networks - do not need to be insulated. This not only reduces investment costs, but also offers a particular advantage: the uninsulated pipes themselves act as geothermal collectors and can draw energy from the ground or feed it into the ground.

Decentralised brine/water heat pumps are installed in the connected buildings. These utilise the cold grid as a heat source and raise the temperature to the level required for heating and hot water. In summer, the system can also be used for cooling by transferring excess heat from the buildings into the grid and thus into the ground. This seasonal storage in the ground contributes to the regeneration of the system.

Key advantages:

1. energy efficiency

  • Minimised heat loss due to low system temperatures
  • Utilisation of the pipes as an additional heat source (collector function)
  • Possibility of seasonal heat storage in the ground
  • Bidirectional operation enables heating and cooling
  • Significantly higher efficiency of brine/water heat pumps compared to air/water heat pumps due to more constant temperature level of the heat source

2. economic efficiency

  • Lower investment costs by dispensing with pipe insulation
  • Reduced operating costs due to minimised heat loss
  • Smaller dimensioning of the coupled source systems possible
  • Integration of photovoltaics for heat pump operation possible

3. sustainability

  • Can be designed to be completely fuel-free

  • High proportion of renewable energies

  • Utilisation of local energy sources

  • CO2-neutral operation with the use of green electricity

4. flexibility and future-proofing

  • Modular design enables step-by-step expansion
  • Integration of various renewable energy sources possible
  • Adaptable to different building types and standards
  • Load shifting through underground storage possible

5. operating advantages of brine/water heat pumps

  • Significantly lower noise levels compared to air/water heat pumps, as no outdoor unit with fan is required
  • Higher annual coefficients of performance due to more stable temperature level of the heat source
  • Better efficiency, especially during the heating period, when air/water heat pumps become inefficient at low outside temperatures
  • Less maintenance required due to fewer moving parts and protected operation
  • Longer service life of system components


LTDHC are particularly suitable for new development areas with buildings that meet the latest energy standards. The decentralised structure with heat pumps in each building enables individual control and optimisation. By integrating photovoltaic systems on the roofs, part of the electricity required by the heat pumps can be generated directly on site.

Planning aspects

When planning a LTDHC, a number of special features must be taken into account:

  • Geological suitability of the subsoil must be tested
  • Water law authorisations are required
  • Sufficient area must be available for any geothermal probes
  • Buildings should be designed for low-temperature heating systems
  • Coordination with other supply lines necessary


Experience from realised projects shows that ground source heat pumps are a technically mature and economically attractive option for the sustainable heat supply of neighbourhoods. They combine the advantages of near-surface geothermal energy with efficient heat pump technology and offer a high degree of flexibility for future developments.

For municipalities, district heating networks offer the opportunity to effectively realise their climate protection goals in the heating sector and at the same time create a future-proof infrastructure for their citizens.

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