According to the EU Strategy on Heating and Cooling (2016), the contribution of district heating (DH) in the EU accounts for 12% of the total final heating and cooling energy consumption. Furthermore, it is highly concentrated in a few Member States and only a limited share of DH networks is highly efficient and based on renewables. However, district heating networks present a high potential for the transition of the heat sector, both technically and organizationally. They are able to integrate efficiently biomass and other renewable energies and they could facilitate sector coupling (coupling between heating, electricity and mobility).
In order to use this potential, many district heating networks must first upgrade the existing distribution system, including the substations and consumer connections: reaching lower leakage rates and heat losses, reducing operation temperatures, adapting piping dimensions and hydraulic, introducing modern IT-based management systems and options for user control. This makes the heat distribution more efficient, but also improves the efficiency of the heat generation. Moreover, DH systems allow the integration of biomass, other renewable energies, excess and waste heat. In order to have an optimized impact, the retrofitting measures should therefore begin with the retrofitting of the distribution network, including measures regarding substations and heating system of the connected buildings. In a further step, efficiency measures can be implemented on the generation side and the share of renewable and waste heat can be introduced and increased gradually. This must go hand-in-hand with predictions of future heat demand as well as with efficiency measures on the end use of heat.
The EU project Upgrade DH (H2020; Contract No. 785014; www.upgrade-DH.eu) supported the upgrading and retrofitting process of DH systems in different climate regions of Europe, covering various countries. The target countries of the Upgrade DH project were Bosnia-Herzegovina, Denmark, Croatia, Germany, Italy, Lithuania, Poland, and The Netherlands. In each of the target countries, the upgrading process was initiated for concrete DH systems of the so-called Upgrade DH demonstration cases (demo cases). The gained knowledge and experiences were replicated to other European countries and DH systems to leverage the impact.
Core activities of the Upgrade DH project included the collection of the best upgrading measures and tools, the support of the upgrading process for selected district heating networks, the organisation of capacity building measures about DH upgrading, financing and business models, as well as the development of national and regional action plans. In addition, an image raising campaign for modern DH networks was carried out in the Upgrade DH project.
In conclusion, the Upgrade DH project was very successful as it surpassed the foreseen impacts as shown below. A highlight is that several of the upgrading measures were already implemented during the lifetime of the project, which was not expected. This shows the high need and value to upgrade DH systems.
