IEA-DHC Annex TS2: Implementation of Low Temperature District Heating Systems

The aim of the Annex TS2 is to implement low-temperature district heat networks (LT-DH or 4GDH, the 4th generation of district heating). Therefore, the Annex TS2 is a platform in which the prerequisites for the implementation are established with international experts.

Short Description

In Lund et al. (2008), the concept of 4 Generation District Heating (4GDH) is outlined as follows: "The 4th Generation District Heating (4GDH) system is consequently defined as a coherent technological and institutional concept, which by means of smart thermal grids assists the appropriate development of sustainable energy systems.4GDH systems provide the heat supply of low-energy buildings with low grid losses in a way in which the use of low-temperature heat sources is integrated with the operation of smart energy systems. The concept involves the development of an institutional and organisational framework to facilitate suitable cost and motivation structures".

The IEA DHC Annex TS2 objective is to facilitate the implementation of 4GDH. It is a framework that promotes the creation of preconditions for 4GDH implementation with an international group of experts.

In TS2, four thematic areas that are imperative for increased 4GDH implementation will be explored.

  1. Technology: the necessary technological solutions for 4GDH implementation.
  2. System functioning: focused on how well the technology operates.
  3. Demonstration: analysis and evaluation of demonstration projects.
  4. Competitiveness: previous demonstrators are evaluated and efficient business models for 4GDH are explored.
  5. Dissemination and Handbook: collection of results and development of a handbook for LT-DH and documentation of what kind of technology, system functions and business models are needed. The intention is to reach the objective of increased 4GDH implementation by providing tools, guidelines, recommendations, best-practice examples and background material for designers and decision makers in the fields of building, energy production/supply and politics.

The five topics will be summarized and the information generated will be disseminated in the form of a 4GDH handbook. The handbook will be complemented by training workshops for academics, users, DH industry and policy makers.

Existing know-how for developing new district heating concepts was compiled in TS1. The activities undertaken in TS2 will resort to existing knowledge and, in conjunction to both evaluation of previous demonstrators and new demonstrators, will generate new knowledge of value for 4GDH implementation. TS2 will build on the experience of previous research on 4GDH. To increase the impact of IEA DHC Annex TS2, a close collaboration with other IEA Annexes and related activities is to be established in order to introduce a bi-directional exchange of information. On the one hand, information on already existing activities will be the starting point of Annex TS2. On the other hand, new activities shall be executed to realize preconditions of Annex TS2.


Austria, Denmark, Germany, Finland, Norway, Sweden

Contact Address

Roman Geyer
AIT Austrian Institute of Technology GmbH
Giefinggasse 2
A-1210 Wien