In Freiburg Dietenbach, a new district is being built for about 16,000 people. The heat will be supplied via a district heating network from a central heat generation plant. Large-scale heat pumps will be used, which will use groundwater and wastewater as heat sources, and the new development cooperation will also be integrated into the WV West. 6 low-temperature heat pumps and 3 high-temperature heat pumps with the refrigerant ammonia are planned. In addition to the heat pumps, the groundwater heat exchangers, waste water heat exchangers, pressure maintenance, pumps, control cabinets, transformer stations and also small ancillary rooms such as storage, toilets and social rooms are also accommodated in the development cooperation. The media district heating, groundwater, sewage and electricity must be introduced into the building in development cooperation.

The building should be completed in mid-2025 so that plant construction can then begin, which will take about a year. The supply of heat from the new energy centre is scheduled to begin in mid-2026.

The energy center will be designed as a large machine hall, in which 6 low-temperature heat pumps with a thermal output of approx. 1,800 kW each will use the heat sources groundwater and wastewater in the final expansion. In addition, the Dietenbach energy centre will be integrated into the large West heating network in Freiburg. In order to be able to serve this, a further three high-temperature heat pumps, each with an output of approx. 1,800 kW, are planned. The heat pumps are installed in a separate room within the hall due to the toxic refrigerant ammonia. This room must also be equipped with storm ventilation in case of refrigerant leakage.

Groundwater is integrated via 6 plate heat exchangers. Wastewater is integrated via 6 heat exchangers, whereby the use of wastewater is put on the back burner and the actual realization has not yet been conclusively clarified. Two buffer tanks with 150 m³ each are planned on the NT side, and 1 buffer tank with 150 m³ on the HT side. All three buffer tanks are located in the outdoor area. For the installation of the pipelines within the hall, a second level is partly built on a second level in steel construction. The floor area for the building is 60 m x 30 m. The height of the building is 8 m.

Redundant network pumps for the district heating network, pressure maintenance, water replenishment and water treatment and a plate heat exchanger for decoupling NT and HT circuits are planned. The hydraulic diagram is attached.

For the power supply, 2 transformer stations with 2.5 MVA each are planned. All switchgear for the power cables and control cabinets of the electrical installation and the I&C are installed in the energy center.

The scope of this call for proposals includes service phases 3-8 for, among other things:

• Heat generation system consisting of large-scale heat pumps

• Groundwater heat exchanger

• Waste water heat exchanger (optional at a later date)

• Heat exchanger between NT and HAT circuits

• Mains pumps, pumps in the plant

• Shut-off and control valves, safety devices

• Pipelines with thermal insulation with sheet metal jacket

• Buffer storage in the outdoor area

• Measuring equipment (heat, pressure, temperature)

• Room cooling via groundwater

• Druckhaltung

• Automatic water replenishment with water treatment

• Storm ventilation for the installation room of the heat pumps

• Sanitary installation (toilet, sink, sink)

• Fastening systems and steel construction for pipelines (partly also at the architect's site)

• I&C technology for the entire system

• fire protection

•Documentation

Optionally, further services for electrical planning can be offered in addition to this tender

• Control cabinets for electrical distribution

• Wiring for power cables

• Transformer stations

• Cabling for low-voltage and data network

• Cabling for I&C technology

• Lighting, sockets

• Grounding and lightning protection

• Cable management system consisting of flatbeds and pipes

•Documentation

This tender includes:

• Adoption of previous drafts, sketches and calculations

• Coordination with the other trades and planning according to the service phases of the HOAI, preliminary planning up to object supervision (HOAI service phases 2 to 8)