Technical improvement potential of large district heating network: application to the Case of Tallinn, Estonia

District heating (DH) operators should relentlessly improve district heating networks (DHNs) for staying competitive in the energy market and for offering better service to consumers in comparison to local heating. Tallinn DHN started providing heat to consumers from the year 1959 and evolves according to external condition. Major changes have been made to about 440 km of the DH network due to the fast city development and the implementation of the DH operators' development strategy since early 1990s. In order to maintain the proper technical condition of the DH network and to reduce heat loss from the DHN, the pipelines are well-maintained, renovated and repaired. The improvement analysis of large DHN and renovation influence on DH network parameters is presented in the paper. Technically possible future improvement scenarios for the Tallinn DH network were determined. The methodology for the Tallinn DHN improvement potential evaluation includes an analysis performed to replace the existing pipelines with the same internal diameter size and optimised diameter pre-insulated pipes. (C) 2018 The Authors. Published by Elsevier Ltd.