Generations of district heating networks
District heating networks have been around for quite some time. They exist for more than hundred years, and, just like humans, have evolved into different generations.
The first generation of district heating networks is roughly situated between 1880 and 1930, the second generation between 1930 and 1980, and the third generation between 1980 and 2020. The new generation, the fourth - 4G - emerged in 2020 and is expected to run until 2050. As we have barely started using 4G and, moreover, 4G is not the standard yet: 90% of all new networks being installed in the EU are currently 3G.
Figure 1: Illustration of the concept of 4th Generation District Heating in comparison to the previous three generations 
The transition between these generations is represented by disruptive innovations. For 1G → 2G this was the transition from steam to water as an energy carrier, for 2G → 3G: pre-insulated pipes were used, and now we come to 'digital district heating networks' (3G → 4G), adding information and communication technology - ICT -, 'smart energy' to the infrastructure.
You can add ICT to district heating networks in all kinds of ways, both in the design and in the operational phase, when an existing district heating network is being exploited.
Let us first, chronologically following to the evolution of district heating networks, consider the design phase.
District heating design
In the past, district heating networks, and piping systems in general, were designed according to the experience of expert designers specialised in the subject matter: which point is connected to which, where do the pipes run, what are the diameters of the various pipes. Then came the first digitalisation: the design of district heating networks was no longer drawn with a pen, ruler and paper, but via drawing programs on computers, performed by a human designer. The next step was automation where routing algorithms take over the role of the human designer to calculate pipe routes, dimensions and plot them on a geographic map. These algorithms keep on improving and are also studied at EnergyVille.
Not only pipes, but also active district heating components are making more use of digitalisation in their design: nowadays heat exchangers with dimples, and more recently also with fins, already exist. The new generation of heat exchangers are designed according to computer models with more amorphous internal structures, which can come to reality with 3D printing.
Additionally, nowadays a so-called "digital twin" is made of active district heating components: a digital copy is made of each component, which contains all physical data such as its disposition, dimensions, and physical characteristics. For example, a fully digital model is made of the entire district heating network before even one pipe is put into the ground. This is currently often still a static model, and once the digital twins have fulfilled their goal in the design, they are put on non-active. However, these digital twins could also be perfectly used in the operational management of district heating networks. And this seamlessly leads us to the second and most important phase in the life of a district heating network.
Operational management of district heating networks
When talking about the operational management of district heating networks, we imagine an operational centre where several human operators keep an eye on the proper operation of the infrastructure and the active components. They ensure that production provides sufficient heat, that the heat is distributed via the piping system, and that the connected buildings all receive sufficient heat. Next to this "smart monitoring" of the district heating network, the district heating network manager also wants to be able to make the right decisions at any time about the temperatures to be supplied, the heat sources to be switched on/off, etc. We call this aspect "smart control". If you already have a digital twin, which is a digital copy of the real district heating network, you could use it in a dynamic way: via data exchange systems in the physical world, the data in the digital twin is brought up to date in real time, so that the operator has an up-to-date and correct representation of what is happening outside at all times.
And hence we arrive at a first important aspect of the operational digitalisation of district heating networks: data exchange.
Data exchange refers to data going in two directions: from the local active heating elements/buildings to the central management (aka monitoring, acquisition or obtaining data), but also vice versa, from the central management to the local active heating elements/buildings (aka management, control). In an industrial context, the data exchange systems are often referred to as SCADA systems, supervisory control and data acquisition.
These data exchange systems equally show a major evolution, called Internet of Things - IoT -: all things, including all "heat components", will eventually be connected to each other via data lines. Several heating network operators are already working on this: modernising and data connecting their local heat emission stations. Where they used to be relatively blind to what happened to the heat in local heating systems, more and more effort is put into obtaining data from local heat systems, linked to the possibility to intervene and control locally from a distance. This is to provide better customer service. As an example, the 'alarm' system when something happens at the customer's home is no longer a customer who calls to say: “I feel very cold although I have the thermostat set to 25 ° C” or “There seems to be water leaking from the incoming duct”. Then it is already too late. It is the active and preventive operational maintenance of the district heating network without the customer noticing anything, let alone losing any comfort.
Well, we now have data about our district heating network, and we can also control it from the central operational management, but we still need human operators to make useful use of this data. We also know that computers can interact with larger amounts of data much faster than humans can. Can't we use ICT to further digitalise operational management? And hence we arrive at a second important aspect of the operational digialtisation of heat networks: data intelligence.
Data exchange and collection in itself do not have much value. You must already be a real genius who can "read" a ceaseless stream of ones and zeros. That is why we have to convert data into information, and information into knowledge. That’s something people can work with. With data intelligence, smart algorithms, machine learning, or artificial intelligence, insights and decisions can be automatically be generated by computers. This is already happening in various industries, and even mission critical industries, just think of the automatic pilot in aircraft or (financial) trading systems.
There will soon be a high demand for this by district heating network operators: once they have their data acquisition and control capabilities effectively operational in their district heating network infrastructure, and the investment has been made, the question will arise how this will lead to better returns, improved sustainability and increased customer satisfaction. Then smart technologies, such as the STORM District Energy Controller , will be the answer: in an automated, self-learning way, a district heating network as a whole will become more reliable, more profitable and more sustainable. This STORM District Energy Controller also uses the thermal mass of buildings to smooth out or shift the peaks of the heat demand, so that the peaks on the production side are also flattened or shifted. This results in less use of expensive fossil fuels - such as oil - in favor of cheaper more sustainable base fuels - such as wood chips.
Suppliers of customer satisfaction-enhancing products and services for district heating networks will therefore increasingly be classified as ICT and software companies, in an important addition to the more traditional heat technology suppliers.
And to come full circle, operationally active digital technologies will also have a significant impact on the design phase. After all, if you need less large production resources, pipes, heating elements during the operational phase, due to the use of digital technologies, you can take this into account during your design phase, so that the basic network can become cheaper.
What we have just told is a first introduction, an incentive to awareness, of the digitalisation wave that will also engulf us in the field of sustainable heat, for a more efficient and sustainable world. If you want to know more about the digitalisation of district heating networks, we strongly recommend reading the Digital Roadmap for District Heating & Cooling , to which we have actively contributed.
- Digitalisation of district heating networks applies to both the design phase and the operational phase.
- Data intelligence is a big next step in the fourth generation district heating networks, after ensuring connectivity and bi-directional data exchange between local heat elements / buildings and central management.
- Suppliers of customer satisfaction-enhancing products and services for district heating networks will increasingly be categorised as ICT and software companies, in an important addition to the more traditional heat technology suppliers.
 4th Generation District Heating (4GDH) - Integrating smart thermal grids into future sustainable energy systems, Henrik Lund, Sven Werner, Robin Wiltshire, Svend Svendsen, Jan Eric Thorsen, Frede Hvelplund, Brian Vad Mathiesen, March 2014, https://www.sdu.dk/-/media/files/om_sdu/institutter/iti/forskning/nato+…
 STORM District Energy Controller: smart controller for district heating networks, EnergyVille, https://www.energyville.be/en/storm-district-energy-controller
 Digital Roadmap for District Heating & Cooling, DHC+ Technology Platform c/o Euroheat & Power, version 2, July 2019, https://www.euroheat.org/wp-content/uploads/2018/05/Digital-Roadmap_fin…