Aesch heating plant commissioned: another key milestone in the decarbonisation of district heating in the Birs Valley
The decarbonisation of district heating in the Birs Valley has reached another important milestone: the new heating plant in Aesch has gone into operation and is already supplying several properties with renewable heat. The inauguration ceremony also featured the presentation of the Birstal district heating network.
On Friday, 7 November 2025, Primeo Energie, together with the local and citizens’ municipalities of Aesch, officially unveiled the new heating plant for the Aesch district network. Guests and media representatives also learned more about the neighbouring Birstal network, whose large central plant in Arlesheim now supplies renewable heat to buildings in Arlesheim, Münchenstein and Reinach.
“The energy transition is, to a large extent, a heat transition,” said Cédric Christmann, CEO of Primeo Energie. “With the new plants in Aesch and Arlesheim, we are building a sustainable, regional heat supply. I would like to thank the municipalities of Aesch, Arlesheim, Münchenstein and Reinach for their commitment and cooperation. Only together can we successfully realise this heat and energy transformation.”
Renewable energy sources for the Birs Valley
Both plants rely on renewable energy. Oil-fired boilers are installed only for peak loads or redundancy. The Aesch plant is equipped with a heat pump and two wood-fired boilers. The 1-megawatt (MW) heat pump, commissioned in mid-October, uses outdoor air in summer and flue gas condensation from the wood boilers in winter.
The smaller wood boiler (1.2 MW) will go online in mid-November, followed by the larger one (2.4 MW) in January 2026. Both are fuelled with wood chips from the nearby Angenstein forest, ensuring short transport routes and a further improved CO₂ balance. The total renewable capacity is around 4.6 MW, with a renewable share of at least 80%.
With an annual heat output of around 16 gigawatt hours, the system can theoretically supply up to 1,600 average Aesch households with sustainable heat. From its site at Weidenring, the network currently supplies northern Aesch—including the VIVO complex, BWT-AQUA buildings, the Büntengarten, Im Egg and Fiechtenacker residential developments, and the Schützenmatt schools. In the coming years, the network will be expanded, densified and connected to existing systems.
Aesch implements its energy strategy consistently
By commissioning the wood-based district heating network, the municipality of Aesch is consistently implementing its adopted energy strategy, focusing on resource optimisation, renewable energy, sustainable heating and cooling, and clean mobility, with the goal of achieving net zero by 2050. The project was realised in record time: just four years from feasibility study to inauguration, in partnership with the citizens’ municipality and Primeo Energie.
Next steps are already under way: through a Smart City project and a feasibility study for a multi-energy system (heat–electricity–storage), Aesch will test further measures to optimise resource use, supported by a CHF 100,000 grant from SuisseEnergie.
Primeo Energie’s largest heating plant in Switzerland
The new Arlesheim heating plant is the heart of the Birstal district heating network. It supplies renewable heat to properties in Arlesheim, Münchenstein and Reinach. Its energy sources include locally available waste wood and, at a later stage, waste heat from buildings, data centres and industrial processes at uptownBasel.
The facility is equipped with two biomass boilers rated at 7 and 12 MW. Up to four heat pumps of 4.5 MW each can be added to recover waste heat. Once fully expanded, the plant will have a total capacity of 40 MW—enough to heat approximately 5,100 households.
The Birstal network began delivering heat at the end of 2024 and is one of Primeo Energie’s largest heating projects. It connects 25 existing local networks in Arlesheim, Münchenstein and Reinach, as well as the uptownBasel and Primeo Energie sites, all supplied with renewable heat. The network is expected to be largely completed by 2035.
Together, these two new district heating systems are central components of Primeo Energie’s heat strategy, aimed at progressively replacing fossil fuels with renewable sources, making full use of regional resources, and contributing significantly to Switzerland’s Energy Strategy 2050.
Primeo Energie has been building and operating district heating networks and systems for 40 years and supplies more than 30,000 customers with heating and/or cooling in Switzerland and France.
Media contacts
• Primeo Energie — Viktor Sammain, PR Editor, Tel. +41 61 415 41 08, medienstelle@primeo-energie.ch
• Municipality of Aesch — Roman Cueni, Head of Administration, Tel. +41 61 756 77 01, Roman.Cueni@aesch.bl.ch
• Citizens’ Municipality of Aesch — Thomas Häring, Council Member, Tel. +41 79 311 97 13, t.haering@bluewin.ch
