Carbon footprint analysis of the district heating supply chain: From heat production to infrastructure

District heating is pivotal in urban decarbonization. As cities strive for climate neutrality, understanding emissions across the district heating supply chain is essential. Yet most studies focus on heat generation and fuel supply, while impacts of distribution infrastructure receive far less attention. This study closes that gap by delivering the first system-wide, bottom-up carbon footprint assessment of a metropolitan district heating network using real operational data from Berlin. Results show fuel combustion accounts for about 87% of total emissions, plant construction for 2%, and the distribution network for roughly 11%. Around 70% of network-related emissions stem from civil engineering activities such as excavation and backfilling. When comparing plastic casing pipes and ducted steel pipes, distinct embodied emission profiles emerge. However, civil engineering impacts remain the dominant factor. In addition, road restoration proves critical, as asphalt reinstatement generates nearly twice the emissions of natural stone pavement. Building on this, a scenario analysis indicates that bundling house-connection works can cut emissions by 12.8% by avoiding repeated excavation and transport processes. Looking ahead, as heat generation becomes increasingly decarbonized, the relative importance of infrastructure emissions will rise, making low-carbon construction and planning strategies indispensable. This approach calls for integrating carbon-footprint accounting into heating plans and regulations, prioritizing low-emission materials, and coordinating construction processes. The study offers a system-wide evidence base to help policymakers and utilities design infrastructure strategies aligned with climate-neutral district heating. • Infrastructure construction contribute up to 71% of emissions in the district heating network. • Network construction accounts for 11.2% of CO 2 emissions in the supply chain. • Using asphalt for pipe installation doubles CO 2 emissions compared to using natural stone. • Bundled house connections reduce emissions by 12.8%. • First systematic CO 2 analysis of Berlin’s district heating infrastructure.