Heat transition in Saarland – status quo, potential, and areas for action
The study “Wärmewende im Saarland – Status quo, Potenziale und Handlungsfelder” by FfE and IREES, commissioned by the Saarland Ministry of Economics, Innovation, Digital Affairs, and Energy (MWIDE), provides a comprehensive overview of the current condition of Saarland’s building stock and its heat demand, as well as the possibilities and limitations of greenhouse gas‑neutral technologies for heat supply in Saarland. Small‑scale results determined using geodata analyses are made available to municipalities as guidance and support for Municipal Heat Planning (KWP). A PDF version of the study can be downloaded further down on this page. Selected results are described below.
Figure 1 provides an overview of the current status of Saarland’s residential building stock. Data from the 2022 Census shows that many residential buildings in Saarland are older and are still predominantly heated with fossil fuels [1]. Furthermore, single‑ and two‑family houses characterize large parts of the region. Thanks to the small‑scale census data, it is possible to analyze where older buildings are concentrated, which heating systems are used, and which building types dominate.
In addition to analyzing the building stock, the study also examines the distribution of existing gas and heat network infrastructure in Saarland. Heat networks are primarily concentrated along the Saar district heating corridor and within the city of Saarbrücken, with several smaller heat networks in additional municipalities.
To estimate future heat demand developments, renovation and climate change assumptions from the “With‑Measures Scenario” (MMS) of the 2025 greenhouse gas projections were transferred to Saarland’s building stock [2], supplemented by expected developments in heated floor area. The basis for this is the heat demand for the year 2022, modeled using FfE’s single‑building model HOUSE and the IREES model Invert/ee‑lab [3]. Figure 2 shows the result: Heat demand decreases by around 25 % by 2045, with a stronger decline in private households compared to the commercial, trade, and services (GHD) sector.
Analogous to the Municipal Heat Planning process, this study supplements the status quo analysis with a comprehensive potential assessment. Its aim is to highlight the possibilities and limitations of different greenhouse‑gas‑neutral heating technologies in Saarland and provide municipalities with small‑scale insights as guidance for their heat planning.
A major focus is on the potential for heat networks, as heat networks play a key role in the heat transition, especially in densely built‑up areas. For the analysis, FfE’s HeatGrid heat network potential model was used, which identifies possible heat network areas using building‑level geodata and heat demand information. Two scenarios with different connection probabilities were modeled. The results in Figure 3 show clearly differing potentials depending on the scenario. They offer initial guidance on where heat networks could be economically viable but do not replace detailed local assessments, as factors such as ownership structures, local heat sources, subsurface conditions, or individual building requirements are crucial for realizing heat networks.
In addition to heat network potentials, the study examined heat generation potentials for the following technologies: decentralized air‑source heat pumps, industrial and commercial waste heat (see Figure 4), river‑water heat pumps, biogenic fuels, shallow and deep geothermal energy, solar thermal energy, wastewater heat, and hydrogen. Results are provided at the municipal level, cadastral district level, and in some cases at the hectare scale. Potentials for centralized heat generation in heat networks were then compared with the identified heat network potentials to assess how much renewable heat could be supplied through heat networks.
For a strategic classification of heat supply options, Saarland was divided into several clusters based on key criteria such as heat network potential, local renewable heat sources, and existing infrastructure. The spatial cluster map (see Figure 5) illustrates which areas share similar starting conditions and therefore offer comparable solution spaces for the heat transition. These clusters serve as the basis for deriving specific fields of action and measures for each area type, providing municipalities with support for developing their heat strategies.
Further Information:
Literature:
[1] Results of the 2022 Census – Building and Housing Survey: https://www.zensus2022.de/static/Zensus_Veroeffentlichung/Regionaltabelle_Gebaeude_Wohnungen.xlsx; Wiesbaden: Statistical Offices of the Federation and the Länder, 2024.
[2] Greenhouse Gas Projections 2025 for Germany (Projection Report 2025). Dessau-Roßlau: German Environment Agency (Umweltbundesamt), 2025. DOI: 10.60810/openumwelt7906.
[3] Steinbach, Jan: Model-based analysis of policy instruments to promote renewable energies and energy efficiency in the building sector. Dissertation. Published by Fraunhofer Institute for Systems and Innovation Research ISI: Karlsruhe, 2015.
