in issue 38 of our heatbeat Research Newsletter we summarize two interesting research publications from the field of district heating: A report that emphasis the important role district heating can play in both decarbonization and the reduction of fossil fuel imports for Europe, and a paper that shows how heat load forecasting models can keep up with the ever-changing realities of the networks they serve. And beyond that, we share a few more recommendations for interesting papers we found recently.

How District Heating can Support REPowerEU

In a new report titled "Heat Matters: The Missing Link in REPowerEU", Mathiesen et al. aim to show how district heating can play a major role in the EU's efforts to not only decarbonize the energy system, but also fundamentally reduce the dependency on fossil fuel imports. REPowerEU is a plan by the European Commission to save energy, produce clean energy and diversify Europe's energy supplies as a reaction to the disruptions of global energy markets caused by Russia's invasion of Ukraine. And while these efforts have been successful in reducing energy demand and fossil fuel imports from Russia, the report argues that it is lacking a clear strategy to fundamentally redesign the energy system with regard to decarbonization of heating in buildings.

In this context, the report proposes a first goal of increasing the share of district heating to supply 20 % of the European heat demand by both building new district heating networks and extend existing networks, while simultaneously changing their fuel mix to a higher share of renewables and waste heat sources. The underlying scenario analysis shows that this boost of district heating is one of the most efficient solutions to reduce natural gas imports. In addition, a scenario for a redesigned energy system 2030 also considers more heat pumps and energy efficiency gains in buildings as well as electrification and efficiency gains in the industry sector. Together, these measures are expected to reduce natural gas imports by 15 % more than the European Commission’s current Fit for 55 and REPowerEU plans.

Beyond that, the report argues for a goal of district heating covering 48 % of Europe's heat demand in 2050. According to the report's analysis, its scenario for 2050 would achieve a 20 - 30 % lower primary energy input comparted to the European Commission's reference scenario at around 10 % lower total costs. To achieve this, the report assumes a lower reduction of the building stock's heat demand (40 % compared to 55 % in the reference scenario) and instead proposes district heating as a more cost-efficient way to integrate renewable energy source into the heating sector.

Handling Concept Drift in Heat Load Forecasting

As the digitalization of district heating networks makes progress and more measurement data is available, the potential applications for accurate heat load forecasting increase significantly. Yet, a central challenge for data-driven heat load forecasts is to keep the forecast model up to date with reality. In a real district heating network, the heat load for a given set of input data (e.g. the outdoor air temperature at a given time) may change e.g. due to new buildings being connected to the network, other buildings being retrofitted to reduce their heat demand, and building occupants changing their behavior with impact on the heat demand. This potential widening of a gap between a forecast model and the changing real system is called concept drift. And the paper "Heat Load Forecasting: Handling Concept Drifts in District Heating Systems" by Mielck et al. shows an interesting evaluation of these challenges and solutions to address concept drift in heat load forecasting for district heating.

The paper compares different strategies to handle the challenge of concept drift. As a conclusion, the paper shows how frequent re-training of the model based on most recent data as well as online-learning (incorporating new data without the need to completely retrain the forecast model) can sufficiently prevent concept drift for a use case of heat demands changing due to new buildings being connected to a network. While the frequency of re-training for real-world applications must be carefully evaluated in each case, this study is a good example for how concept drift can be addressed in heat load forecasting.

Further Reading

In addition to the two publications summarized above, we found many more interesting papers published last month, two of which we want to also mention briefly: The paper "Impact of Energy-Related Properties of Cities on Optimal Urban Energy System Design" discusses how certain properties of cities shape the optimal design for a suitable urban energy system. And the paper "District cooling services: A bibliometric review and topic classification of existing research" gives a good overview of current research about district cooling.

The next issue of our newsletter will be published on January 3, 2024. Until then, thank you for staying with us in 2023 and we wish you a good start to the new year.