Wales & West Utilities (WWU) is a large gas distribution network spanning Wales and the South West of England, serving a diverse mix of rural communities and urban centres across a region with significant variation in heat demand and existing energy infrastructure. The network faces substantial decarbonisation challenges as it transitions away from natural gas, and as the UK works towards its 2050 net zero target, district heating is identified as a key pathway for WWU towards a future low-carbon energy system.
Recognising these opportunities, City Science and Apollo were commissioned by WWU to conduct a district heating feasibility and network impact study across the WWU licence area. The study aimed to identify heat network hotspots across the WWU area and two potential heat network opportunities, one in an on-grid network area and one in an off-grid network area which helped enable the organisation to move from strategic understanding to informed action.
City Science Response
Review of existing studies
We began with a literature review, providing a comprehensive overview of district heating in the UK, including common network configurations and the key stages of the Heat Network Code of Practice (CP1). We reviewed case studies from established and developing projects such as the Bristol City Leap heat network and Cardiff Council heat network proposals to extract lessons learned, best practices, as well as the different commercialisation models to inform WWU’s potential role in future schemes. We also applied our understanding of local energy planning across the WWU licence area to identify where district heating networks currently exist and where high-potential areas for future development have been highlighted.
Low Carbon Heat Supply & Demand Profiling
We carried out a comprehensive review of viable low-carbon heat sources, identifying a wide range of options, including the selected technologies: Air Source Heat Pump (ASHP), Ground Source Heat Pump (GSHP), and Water Source Heat Pump (WSHP) for both Cardiff and Llanwrtyd Wells.
Heat demand analysis was conducted using our in-house heat demand model, with outputs verified using gas meter consumption data provided by WWU. This blended approach enabled us to identify anchor demand clusters and accurately model load across the network, assessing the viability of district heating across both on-grid and off-grid locations.
Network Scenarios and Techno-Economic Modelling
Six to eight heat network scenarios were created for each study area, aligning heat clusters with low-carbon heat sources. The proposed potential heat network routing and building connections are shown in the image. We utilised our in-house techno-economic model to analyse cashflows, cost and risk, benchmarking each scenario against a counterfactual for comparative insight
Outcomes
The study identified two potential schemes: an on-grid opportunity in Cardiff and an off-grid opportunity in Llanwrtyd Wells. The Cardiff scheme demonstrated strong economic performance and significant carbon savings, identifying district heating as the lowest-cost, low-carbon heating solution for the identified buildings. In contrast, the Llanwrtyd Wells scheme highlighted the limited viability of a single approach in rural areas with lower demand density, pointing instead to a hybrid model combining communal heating with individual property-level decarbonisation.
Delivered on time and to budget, the study has equipped WWU with a clear, evidence-based understanding of where and how heat networks could impact their network. These outputs provide a strong evidence base to support future capital funding applications, such as the Green Heat Network Fund, should WWU or a partner organisation choose to progress either scheme towards construction.
A summary of the results are shown below: