Münchenstein/Zofingen, 22 September 2025 – The energy service providers StWZ Energie AG and Primeo Energie founded the company «Fernwärme Unteres Wiggertal AG» (FUWI) on Friday, 19 September 2025, in Zofingen. Their goal is to build and operate a climate-friendly district heating network in the Lower Wiggertal region, based on their existing networks in Oftringen and Zofingen.

Expanding a low-carbon district heating supply in the Lower Wiggertal makes an important contribution to implementing Switzerland’s national Energy Strategy 2050 as well as regional climate targets. At the same time, it strengthens local value creation and ensures that energy is produced where it is needed.

Fernwärme Unteres Wiggertal AG

StWZ Energie AG and Primeo Energie aim to expand sustainable district heating in the Lower Wiggertal. To this end, the two companies founded the joint company «Fernwärme Unteres Wiggertal AG» (FUWI) on 19 September 2025 in Zofingen, where the company is also headquartered. StWZ and Primeo Energie are contributing their existing district heating networks in Oftringen and Zofingen to the new company. By pooling their infrastructure, customer proximity, and energy expertise, they are advancing the climate-friendly development of heat supply.
“The energy transition is also a heat transition,” says Michael Schneider, CEO of Primeo Wärme AG. “By establishing FUWI AG together with StWZ, we are laying the foundation for a long-term, future-proof heat supply in the Lower Wiggertal.”
Paul Marbach, CEO of StWZ Energie AG, adds: “By combining regional energy sources with modern technology, we are specifically reducing CO₂ emissions and expanding the range of reliable, decarbonised heat available to our customers.”

Expansion in two phases

The district heating network in the Lower Wiggertal will be expanded in two stages. Phase 1 will start in 2026 with the construction of the network from the erzo waste-to-energy plant (erzo-KVA) towards Oftringen South and Zofingen. The existing district heating networks of StWZ in Zofingen and Primeo Energie in Oftringen will be integrated. The first heat deliveries to customers from the new network are planned from summer 2027 onwards.
Paul Marbach explains: “The heat will come from the erzo waste-to-energy plant as well as from StWZ’s existing decentralised energy centres.”

According to Michael Schneider, Phase 2 will see the network extended to the municipalities of Aarburg towards Olten, Rothrist, Strengelbach as well as other areas of Zofingen and Oftringen. Existing local district heating networks will also be integrated. This second stage of expansion is planned from 2030 at the earliest and depends on the construction of a new waste-to-energy plant. For this to proceed, the residents of Oftringen will need to approve the rezoning of the required land in spring 2026. Implementing both phases will enable the supply of heat to 10,000 households and save 30,000 tonnes of CO₂.

Media contacts

Primeo Energie
Viktor Sammain, PR Editor, +41 61 415 41 08, medienstelle@primeo-energie.ch

StWZ Energie AG
Paul Marbach, CEO, +41 62 745 32 14, p.marbach@stwz.ch