Upgrade to low temperature district heating in Karlova district (Tartu)

The aim of the pilot measure is the elaboration of a feasibility study for energy efficient renovation of buildings by connecting them to the DH grid in Karlova. The study includes requirements for renovation of buildings, description of renovation process and comparison of different energy sources and their cost. It serves as a reference document for energy companies, municipalities and consumers.


House owners, apartment owners and apartment building managers, local heat supplier, Karlova municipality


Overall aims

  • Awareness-raising for consumers and change of attitudes for transition from local heating systems to DH and especially to show benefit of the transition to LTDH.
  • Testing of LTDH implementation strategy, recognition of missing measures and arguments and suggestion for strategies improvement.
  • Reduce CO2-emissions from DH system.

Implementing Partner: Tartu Regional Energy Agency


Contact person: Martin Kikas, martin.kikas@trea.ee


Innovative approach and benefits

Karlova district is located close to the city centre in Tartu with ca 8300 inhabitants. Karlova is one of historically wooden buildings district in Tartu. Most of the district’s existing buildings were completed in the early 1910´s, some in the 1920s. Karlova buildings are characterized by “a lively bulky structure with numerous roof structures and slats and a unique Art Nouveau façade trim adapted to wood architecture, mainly created by dynamic mouldings of door and window enclosures and frames.” In the backyard are many woodsheds. Most of buildings are not renovated and are using local heating, mostly stoves and fireplaces. Karlova is connected to DH and supplied with main pipeline and there are no restrictions in the heating network. The Existing DH system is 3th generation system and working in range 90/60 degrees. In large district heating systems, the transition to the fourth generation is only possible through the simultaneous development of all components, production, distribution, consumption, but the emphasis must be on the consumer. Because the major challenges are with consumers in developing the system.

An analysis of the total costs of the different energy efficiency levels showed that: the cost-optimal level of apartment building reconstruction is depending on the type of building, either the energy efficiency level of the new apartment building or the low energy apartment building energy efficiency level. A reduction of 70% of energy consumption is possible so that the total cost to apartment owners over 20 years does not increase. The renovation of buildings for using LTDH and installation of a more energy efficient heating system will allow to reduce the energy cost for households and overall environmental impact. At the same time, it will promote the use of LTDH System and rising awareness for both citizens and neighbour municipalities. The feasability study has been presented to wider public including citizens, representatives from DH Companies, municipalities and administrative institutions. Therefore, the lessons learnt from the pilot measures will be used in future low temperature systems in Estonia.

The heat recovery (HR) exchangers and heat pump installed into the system: