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Retrofit of existing districts and buildings using 5GDHC/anergy networks

What role can 5GDHC networks (anergy networks) play in the retrofit of existing districts and buildings? This is the question, we address on this page.

Why are 5GDHC / anergy networks also an important technology for existing buildings?

5GDHC describes heating networks at ambient temperature whose task is to connect several buildings to a central heat source. A classic case is geothermal energy. Geothermal drillings to install geothermal probes is very expensive. If a separate borehole has to be created for each building, this can lead to very high costs. In addition, there is often not enough space for geothermal probes. However, with a 5GDHC network, it is possible to construct geothermal probes at a central location and transport geothermal heat to several buildings. Since 5GDHC networks are very inexpensive to build (compared to conventional heating networks), this solution can be more economical than installing individual geothermal probes for each building.

Building retrofit with heat pumps

The problem with the refurbishment of buildings and neighborhoods is that a complete decarbonization should always be the goal. However, this is not easy to achieve in the context of modernizing old building stock: The use of combustion technologies such as natural gas boilers, oil heating systems or biomass should be avoided whenever possible. This also reduces the dependence on the price development of fossil fuels. Consequently, not many technologies can be considered for heating: In addition to solar thermal collectors, the heat pump is a key technology. However, solar thermal collectors can only cover significant heat demand in summer months. Therefore, they are often installed to support the supply of domestic hot water during summer months. For base load coverage in winter, a heat pump solution should be used if possible. There are two options here: Either air source heat pump or ground source heat pump. Air source heat pumps are less efficient because they have to overcome a very high temperature lift: In winter, the outside air temperature is at its lowest. At the same time, the supply temperature of the heating system is at its highest. This means that the heat pump runs relatively inefficiently and consumes a lot of electricity. In existing buildings, there is also the problem that the flow temperature of the heating system is quite high anyway (60 °C and more) due to old radiators instead of underfloor heating. For this reason, a ground source heat pump can be worthwhile, as it extracts heat from a higher temperature level: The ground temperature is around 8 °C and largely constant throughout the year. This means that the heat pump runs at a higher efficiency and consumes less electricity. However, as described above, it is very expensive to install geothermal probes for each building. For this reason, it may make sense to consider installing a 5GDHC network. This has several advantages:

  • The retrofit is comparatively simple, as it is only necessary to install a heat pump in the building and bring the heat network into the house.
  • Attractive subsidy programs, such as the German Subsidy Program for Efficient Heat Networks (BEW), can be exploited, thus saving considerable investment.
  • Due to the high temperature level of the geothermal heat, the heat pump achieves high annual performance factors (high efficiency).
  • With one renovation measure, several buildings can be converted to renewable heat at the same time.
  • In summer, buildings can be cooled at low cost.
  • As part of the earthworks, further network-related infrastructure (fiber optics) can be laid and old infrastructure (natural gas network) can be dismantled.
  • If a photovoltaic system is also installed in the course of the refurbishment, the own electricity can be used to power the heat pump. This increases the economic efficiency of the PV system and reduces electricity costs.

On our subpages about 5GDHC, you will find a complete list of advantages and disadvantages of 5GDHC networks.

The nPro tool was developed specifically for the conceptual design of 5GDHC networks.

Where is 5GDHC used for the retrofit of neighborhoods and districts?

In general, 5GDHC is predominantly used in newly built districts. In the list of 5GDHC networks you can see in which neighborhoods 5GDHC networks have already been installed and also for which existing neighborhoods such an innovative heating network has been built. One example neighborhood where 5GDHC has been used in existing buildings is the Shamrock Park in Herne. Another example is the modernization of an old building stock in Vienna (project SMART Block Geblerstraße) by means of an anergy network (as 5GDHC network is often called in Austria).

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