Assessing the Impact of District Heating Network Expansion in Edinburgh

Heating buildings accounts for 30% of CO2 emissions in the UK. To address this, our heating systems must be redesigned, improving efficiency and replacing fossil fuels. Renewably sourced district heating networks (DHNs) provide a key solution in densely populated areas. This study addresses the current lack of research into DHN expansion. In doing so, it highlights a unique opportunity at the University of Edinburgh, who currently operate a gas-fired CHP network. To assess the impact of network expansion, heat demand data for all registered properties in Edinburgh is utilised; this is categorised into expansion scenarios reflecting four issues that can be addressed with DH: minimising carbon emissions, reducing the price of heating bills, and improving the energy efficiency of public and domestic listed buildings. Phased expansion of the network was explored through the creation of service areas. Each service area encompasses heat demand points up to 2000m from the Central and King’s Building’s energy centres. Opinion data regarding the relative importance of each scenario was collected and analysed using the analytic hierarchy process, allowing identification of the scenario with the greatest impact. The final stage was generating network routing for this scenario, visualising and optimising DHN expansion. For this, heat demand points were clustered into substations and connected using Dijkstra’s shortest path algorithm. Assuming a 100% renewable network, the greatest impact is achieved with maximum expansion (2000m) from the Central Campus energy centre. In this scenario, a total of 29,678 heat demand points are connected, equating to 113,224 tonnes of CO2 avoided. Whilst this study embodies a high-level impact analysis of DHN expansion, further research is required for practical implementation, including validation of pipe network locations and heat flow modelling.