What is 5GDHC?

5GDHC stands for fifth-generation district heating and cooling. A 5GDHC network is a low-temperature system that supplies buildings with heating and cooling. Such networks are also called anergy networks or ambient loop networks.

A low-temperature network

Water circulates in a 5GDHC network at around 5 to 25 °C. At these temperatures the network can use renewable energy and waste heat efficiently without insulated pipes, and its losses are minimal.

The network connects the buildings with energy sources and with thermal storage, such as borehole fields, buffer tanks or seasonal storage.

Heat pumps in every building

Each building uses its own heat pump to provide heating or cooling. The decentralised heat pumps raise the temperature to what each building needs, for radiators or for floor heating. The challenge: a higher upfront investment and more complex control.

A key advantage is the bidirectional energy exchange. Excess heat can be fed back into the network and used by other buildings, which improves the overall energy efficiency. When some buildings heat while others cool, their demands balance each other, so summer cooling becomes a reason to connect.

Typical sources

Typical sources are groundwater, geothermal energy, waste heat and wastewater. The Quick Check works with six kinds of source: geothermal, waste heat, ground water, surface water, solar thermal and ambient air.

In the use cases of the research project Anergie Leicht Gemacht, groundwater was the most economical source.

Why it matters

5GDHC networks integrate renewable energy and waste heat efficiently and reduce the reliance on fossil fuels. They can also contribute to a resilient, secure and locally available energy supply, because they integrate local energy sources, reduce the dependence on individual energy carriers and allow a flexible exchange and storage of heat and cold.

Where it fits

5GDHC networks can be built in different settlement and building types, but they need suitable technical and economic conditions. The research project Anergie Leicht Gemacht drew these learnings from its use cases:

Existing buildings can be integrated, most of them even without major thermal renovation.
Heat line density decides the economics: above about 1 MWh per metre of trench, networks can beat individual solutions.
Pipes and house connections drive the cost; the trench length dominates the investment.
Micro-networks between direct neighbours are a promising option.

Good to know: the investment comes first, while the revenues come over 25 to 30 years, and every building that stays out raises the costs for the rest.

Where it is harder

The Quick Check indicators show what can weaken the case for a network:

Low building density: the buildings are more spread out, which can increase the network length.
Low heat density: a relatively long network serves a low heating demand.
Unbalanced demand: when heating or cooling clearly dominates, more external energy sources or thermal storage may be needed. An unbalanced demand profile does not automatically make a 5GDHC network unsuitable.

Most challenges are organisational rather than technical: coordination, ownership structures, financing and long-term operation. In the experience of the project, connecting is voluntary, and many owners decide individually: homeowners, housing associations and public buildings.

Examples in practice

Viertel Zwei, Vienna: residential, commercial and public buildings with decentralised heat pumps, on geothermal energy, wastewater and groundwater; in operation since 2017.
Bregenz, Vorarlberg: water from Lake Constance as the source for heating and cooling, run by the municipal utility, Stadtwerke Bregenz; in operation, and the network is being expanded.
Lagarde, Bamberg: existing and new buildings with about 1,200 dwellings, 70 decentralised heat pumps and 5.5 km of pipe, on geothermal energy and wastewater heat; in operation since 2023, with Stadtwerke Bamberg.

How First Move helps

The Quick Check screens a project area: does a 5GDHC network look promising there, and which factors decide it? The Business Plan helps you work out who benefits and who pays, who owns and operates the network, and which risks could stop it.