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Optimal dimensioning of low-energy district heating networks with operational planning - Case study for existing buildings

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Optimal dimensioning of low-energy district heating networks with operational planning - Case study for existing buildings

Publication Date: 28.10.2011 |   Pages: 37-46
Hakan İbrahim Tol and Svend Svendsen
Technical University of Denmark, DK-2800, Denmark

DOI: -


Low-temperature operation in low-energy District Heating (DH) systems is rewarding for increased exploitation of lowtemperature renewable energy sources, heightened efficiency at heat extraction, and intensified energy efficiency at heat distribution. Success of heat delivery in low-temperature operation such as 55 °C in terms of supply and 25 °C in terms of return was achieved through real cases located at Lystrup in Denmark, and “Greenwatt Way” project located at Scotland in UK as demonstration of low-energy DH systems being considered to supply heat to new houses with low-energy class. In our former study the performance of in-house heating systems was investigated for changing levels of supply temperature with consideration given both to current high-heat demand and future low-heat demand value of an existing settlement. The over-dimensions obtained at in-house heating systems originally in design stage resulted in satisfaction of heat demand of the house in low temperature operation. In this paper the operational planning of the low-energy DH systems was investigated to reduce the dimensions of the distribution network with consideration given both to current high-heat and future low-heat demand situations. The operational planning was based on boosting (increasing) the supply temperature at peak-demand situations which occur rarely over a year period. Hence optimal pipe dimensions of low-energy DH systems were investigated based on the dynamic response of in-house heating systems with changing supply temperatures ranging between 55 – 95 °C. The boosting level of supply temperature was considered to be determined separately for current high and future low heat demand scenarios. As a conclusion it was found that 40% reduction in the pipe investment cost could be reached by use of operational planning in comparison to DH network dimensioned according to high heat demand situation.


low-temperature district heating


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