Decarbonizing district heating systems: strategic pathways, effectiveness and carbon footprint from supply chains to infrastructure

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🔬研究者:Provides a harmonized methodology for comparing district heating decarbonization strategies and quantifying infrastructure emissions.

🏢実務担当者:Offers actionable insights on reducing emissions in district heating projects, including infrastructure planning and material choices.

🏛政策担当者:Highlights the need for whole-life carbon assessments and municipal coordination to reduce infrastructure emissions.

District heating plays a central role in the European energy transition. However, its decarbonization is one of the most complex challenges of urban transformation. This dissertation develops an integrated framework that examines district heating systems along their entire value chain. It combines operational, structural, and organizational emissions in a consistent methodological approach. The aim is to comprehensively capture the mechanisms of emission reduction and understand how technical, infrastructural, and planning strategies can jointly contribute to climate neutrality. The starting point is a systematic analysis of existing decarbonization strategies based on the “Avoid–Shift–Improve” model. This model classifies measures according to avoidance, shift, and improvement and covers all relevant stages of the supply chain: from energy sources and conversion to energy management and heat distribution to demand-side and regulatory strategies. The methodology includes a harmonized evaluation of over one hundred studies from the district heating sector, comparative modeling of European district heating systems, and a detailed investigation of emissions from infrastructure and construction processes using Berlin as an example. The results show that emissions occur at all stages of the supply chain and that interventions at one point have an impact on other stages. The harmonized carbon footprint data show that systems based on renewable energies achieve intensities of between approximately −0.001 and 0.091 kg CO₂e per MJ. Fossil fuel systems, on the other hand, have values between 0.04 and 0.31 kg CO₂e per MJ. Combined heat and power reduces emissions by 16 to 70% compared to simple boiler configurations. Large electric heat pumps with a low-emission electricity mix reduce emissions by an average of around 64%. The integration of heat storage systems can reduce emissions in hybrid systems by around 50%. This makes it clear that the switch to renewable heat sources and systemic efficiency improvements have a substantial but not unlimited reduction effect and must always be considered in terms of their interactions with grid operation, demand, and infrastructure. The European comparative analysis also shows that the effectiveness of decarbonization measures depends heavily on the specific context. In countries with a largely decarbonized electricity mix, such as Sweden, large heat pumps achieve emission intensities of less than 0.00003 kg CO₂e per MJ and are among the most effective strategies. In countries with fossil fuel-based electricity generation, such as Poland, reducing heat losses and lowering heat demand lead to greater relative savings than additional electrification of heat supply. Across all contexts considered, it appears that increasing the share of low-carbon heat by one percentage point reduces emissions by an average of 0.0008 to 0.0013 kg CO₂e per MJ of heat supplied. The results of the model-based case studies show that successful decarbonization must be context-specific and gradual, rather than relying on universal “one-size-fits-all” solutions. It also becomes clear that technologies often favored by policymakers do not necessarily deliver the highest marginal mitigation contributions. On this basis, the “Building Infrastructure” study identifies decarbonization in the area of heat distribution as an additional strategy. A detailed carbon footprint analysis of Berlin's district heating network shows that the construction and maintenance of the pipeline infrastructure accounts for around 11% of total supply chain emissions. This corresponds to around 340 million kg CO₂ per year. Around 70% of these emissions are generated in civil engineering, particularly during excavation, transport, and the operation of construction machinery. Only a small proportion is attributable to the production of pipes and the restoration of surfaces. The choice of materials also proves to be an important lever: asphalt causes about twice as many emissions as natural stone. Through coordination of construction work by various utility companies, bundling of interventions in the road space, and optimized logistics, total emissions can be reduced by around 13%, which corresponds to an annual saving of around 43 million kg CO₂. These results underscore the significant importance of infrastructure planning and organization as a previously underestimated but effective tool for reducing emissions. The inclusion of construction and renovation processes in strategic planning transforms infrastructure construction from a background process into an active component of decarbonization. It thus complements existing technical and operational measures with a governance lever. Methodologically, the dissertation contributes to linking the previously separate approaches of carbon footprint analysis and energy system modeling. By standardizing the functional units to one MJ of useful heat and harmonizing the system boundaries with relevant ISO standards, it enables a transparent and comparable evaluation of different technologies and strategy combinations. The combination of qualitative strategy mapping, harmonized carbon footprint analyses, cross-border system modeling, and detailed infrastructure evaluation results in an analytical tool that can be used in scientific research as well as in planning and political decision-making processes. This enables whole-life carbon considerations at the system level. The study concludes that decarbonization of district heating can only be achieved by integrating all levels, from energy generation and network and plant operation to infrastructure construction and institutional coordination. The realization of climate-neutral district heating therefore requires not only clean energy sources, but also coordinated planning of civil engineering processes, conscious material selection, and governance-based control of embodied emissions. This has key implications for policy and practice: whole-life carbon assessments should become mandatory for district heating projects, infrastructure emissions should be integrated into municipal climate budgets, and greenhouse gas emissions should be systematically anchored in tendering and procurement processes. At the same time, municipal coordination platforms are needed to bundle the construction activities of different utilities, thereby reducing emissions, costs, and burdens on urban society. Overall, the dissertation concludes that a successful heat transition cannot be achieved solely by switching to “clean” energy, but rather through a combination of efficient operation, intelligent infrastructure, and institutional cooperation. In this system, tomorrow's infrastructure must be designed as climate capital in order to pave the way for truly climate-neutral heating networks

• openalex https://doi.org/10.14279/depositonce-25601first seen 2026-08-02 18:27:09