Development of sustainable district energy: Cold local heating network for Gronau (Leine)
The development of climate-neutral residential districts requires engineering solutions that go beyond conventional supply concepts. While cities and municipalities are looking for cost-efficient, low-emission energy solutions, cold local heating networks are becoming increasingly important as a central component of sustainable urban planning.
In the new residential quarter in Gronau (Leine), this vision becomes reality. Supported by the technical expertise of M&P Energy – a member of the SIERA Alliance, a network of European environmental and engineering experts, the project integrates a geothermal-based cold local heating network for the efficient and sustainable supply of a diverse building structure.
The quarter comprises 82 single-family houses, 86 semi-detached and terraced houses, 19 apartment buildings and a daycare centre. From the very beginning, the goal was to develop a robust, renewable energy concept that meets both the German climate goals and the strategic engineering principles of the SIERA Alliance.
Geothermal energy as the backbone of the energy concept
To supply heat, hot water and passive cooling, the district is connected to a cold local heating network – a system that distributes low-temperature heat in the district and enables building-specific heat pumps to generate heating energy with high efficiency.
The geothermal infrastructure was designed and technically validated by M&P Energy – a member of the SIERA Alliance, based on comprehensive subsurface modelling, demand forecasts and simulation-based design scenarios.
Key system features
- 114 geothermal probes, each at a distance of 8 metres
- Two probe fields in the northern green areas
- Increase of the probe depth from 150 m to 180 m to ensure permittable and efficient operation of the plant
- Three distribution shafts, connected to the technical center
- Passive cooling via brine-water heat pumps and active regeneration via recoolers
- Four monitoring stations (two groundwater measuring points + two temperature measuring points)
These components result in a tightly interlocking system that is designed for stable thermal performance throughout the year.
Simulation-based planning by M&P Energy
A major development step was the detailed assessment of the geothermal subsurface parameters. M&P Energy used its expertise in hydrogeology, thermal simulation and sustainable energy system design to conduct field investigations and thermodynamic models.
Initial simulations based on the existing 150 m pilot probe showed that the passive cooling requirements could not be achieved. For this purpose, M&P Energy developed a revised simulation model, which led to the installation of a new 180 m pilot probe and optimized planning parameters.
This analytical adaptation ensured:
- Stable performance in passive cooling mode
- Improved long-term thermal balance
- Increased efficiency
- Minimized operational risks
This evidence-based approach reflects the engineering philosophy of the SIERA Alliance: precision, data-based decisions and lifecycle-oriented thinking.
Thermal balance and seasonal regeneration
Efficient geothermal plants are based on both the extraction and regeneration of heat. M&P Energy integrated a thermal management concept that balances the seasonal requirements:
Winter operation: Renewable heat
- Heat pumps extract energy from the subsoil.
- The soil temperatures are falling in a controlled manner.
Summer operation: Passive cooling & active regeneration
- Buildings passively release heat into the underground.
- Dry coolers support active regeneration if required.
- Monitoring ensures compliance with all operational limits.
This bilateral seasonal cycle is crucial for operational stability and efficiency.
Environmental monitoring and permit security
Sustainable energy systems must be both technically robust and environmentally compatible. Therefore, M&P Energy developed a comprehensive monitoring concept:
- Two groundwater measuring points + Two temperature measuring points for monitoring the temperature changes in the probe field and, if necessary, for adjusting the plant operation, observation of thermal propagation
- Heat quantity countsr for monitoring the actual heat extraction and input in the probe field
- Continuous evaluation to protect the environment and ensure operating characteristics
These measures ensure transparency towards authorities and strengthen the ecological orientation of the project within the SIERA Alliance.
An important milestone for the 2030 climate targets
The construction and commissioning of the probe fields and the cold local heating network will begin in 2026 in parallel with the development of the district.
The project shows how renewable district energies can be systematically integrated into modern urban development. Through the combination of geothermal energy, simulation technology and interdisciplinary planning, M&P Energy – a member of the SIERA Alliance – demonstrates how modern infrastructure actively contributes to the 2030 climate targets.
Today, renewable heating and cooling is no longer a supplement – but a central infrastructure for the future.
Call to Action
If you are planning a new residential district, evaluating geothermal potential or looking for a robust, low-carbon energy concept, M&P Energy – a member of the SIERA Alliance can support you from feasibility to implementation. Our experts develop data-based, sustainable energy systems that are designed for long-term performance.
Get in touch with M&P Energy to develop a tailor-made, future-proof energy solution for your neighbourhood. You can also contact the SIERA Alliance to learn how their network of experts can support your long-term energy and sustainability goals.
Together, we stand for ‘Engineering for a Better Tomorrow’.
