Low temperature district heating for future energy systems

The building sector is responsible for more than one third of the end energy consumption of societies and produces the largest amount of greenhouse gas emissions (GHG) of all sectors. This is due to the utilisation of combustion processes of mainly fossil fuels to satisfy the heating demand of the building stock. District heating (DH) can contribute significantly to a more efficient use of energy resources as well as better integration of renewable energy into the heating sector (e.g. geothermal heat, solar heat and biomass from waste), and surplus heat (e.g. industrial waste heat). Low temperature district heating offers prospects for both the demand side (community building structure) and the generation side (properties of the networks as well as energy sources). Especially in connection with buildings that demand only low supply temperatures for space heating. The utilisation of lower temperatures reduces transportation losses in pipelines and can increase the overall efficiency of the total energy chains used in district heating. To optimise the exergy efficiency of a community supply systems the LowEx approach can be utilised, which entails matching the quality levels of energy supply and demand in order to optimise the utilisation of high-value energy resources, such as combustible fuels, and minimising energy losses and irreversible dissipation (internal losses). The paper presents the international co-operative work in the framework of the International Energy Agency (IEA), the District Heating and Cooling including Combined Heat and Power (DHC|CHP) Annex TS1.