Sustainable Transition of District Heating Networks—Upgrading the Performance of DH System Tuzla and Integration of RES Modules

District heating networks present a high potential for the transition of the heat energy sector, both technically and organisationally. They allow integration of renewable energy, improve the overall energy efficiency, as well as facilitate sector coupling (coupling between heating, electricity and mobility). Many district heating systems could be upgraded by improvements at the side of the heat consumption, heat distribution and heat generation. The EU project Upgrade DH (H2020; Contract No. 785014; www.upgrade-DH.eu) supports the upgrading and retrofitting process of DH systems in different climate regions of Europe, covering various countries. Core activities of the Upgrade DH project include 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. Overall Upgrade DH approach should lead to more efficient district heating networks and sustainable solution for the heating sector. The specific upgrading opportunities need to be identified, described, assessed and translated into Key Performance Indicators (KPI) which may allow the results to be monitored as the action gets implemented. In this paper, the upgrading method is demonstrated on Tuzla DH, one of demo-cases considered under Upgrade DH project. In developing the upgrading measures for Tuzla DH, three measurable objectives 20/20/20 were taken into account, namely (i) 20% increasing energy efficiency (reducing annual primary energy demand from 350 GWh down to 270 GWh), (ii) 20% increasing RES (from 0 up to 20% of RES) and (iii) 20% reducing CO2 emission (CO2 cut from today 115,000 t/a emitted in producing 350 GWh of heat down to max. 92,000 tCO2/a. By identified and prepared upgrading measures, those targets are highly exceeded.