The use of EH (excess heat) in DH (district heating) may contribute to increased sustainability through reduced use of primary energy. In Sweden, while biomass has become the most important DH fuel during the last decades, there is a significant amount of industrial EH that could be utilised in the DH systems if it could be shown to be an economically viable alternative. This study addresses the long-term system profitability of a large heat network between a cluster of chemical industries and two DH systems that enables an increased use of EH. An assessment is carried out by scenario and sensitivity analyses and by applying the optimising energy systems model MARKAL_WS, in which the DH systems of the Vastra Gotaland region of Sweden are represented individually. The results show heat network profitability under most assumptions, and that the profitability increases with biomass competition, phase-out of natural gas use and higher CO2 charges, whereas it decreases with the availability of other EH sources in the base load of the DH systems. (C) 2015 The Authors. Published by Elsevier Ltd.