On Saturday, 26 September, residents of the Overhees neighbourhood in Soest can visit the demonstration heat installation at the local petting farm. The 13:00 tour is part of Warme Burendag, organised by local energy cooperative Soester Energie. The programme also includes draught-sealing visits, a tile-removal activity, information stands and neighbourhood litter picking.

The demonstration system has heated the petting farm with pond water for three winters. Separately, a heat exchanger placed in a nearby pond in April 2025 supplies a resident-led mini-network of three houses. That system, known as Warmte uit Vijvers ("heat from ponds"), uses pond water at 10 to 15 degrees Celsius and water-source heat pumps that can raise the temperature to as much as 60 degrees, according to Soester Energie and the industry body Stichting Warmtenetwerk. The cooperative is developing a second mini-network for a nearby row of houses and is working with heating specialist Extraqt on the preliminary design of a larger system.

From three houses to eleven hundred

The ambition is much bigger than the current pilot. A 2023 feasibility study commissioned by Soester Energie from consultancy Syntraal concluded that a network using four of Overhees' larger ponds was technically and financially feasible for roughly 1,100 homes, drawing on underground seasonal heat storage. In August 2025, Stichting Warmtenetwerk reported that the cooperative hoped to begin scaling up in 2026, connect 300 to 400 homes a year from 2027 and reach about 1,100 homes, roughly half the neighbourhood, in 2029 or 2030. Those figures describe the cooperative's proposed timetable, not completed connections.

A provincial heat company remains under study

Soester Energie is one of a number of resident-led cooperatives working on district heating across the province, alongside others including Oog voor Warmte in Utrecht and WarmVreeswijk in Nieuwegein. Their efforts are unfolding alongside a separate province-led study. Since May 2025, the province of Utrecht, the Stedin subsidiary NetVerder and the state-owned Nationale Deelneming Warmte have been exploring a joint Utrechts Warmte Ondersteuningsbedrijf that could help municipalities develop and run collective heat networks. As of July 2026, the partners were still drafting a proposal. In its 2027 budget, presented on 23 September, the province said a formal decision on whether to establish the company was expected during 2027.

RTV Utrecht reported this month that Sophie Schut, director of the cooperative-support organisation Energie van Utrecht, worries the proposed company could crowd out volunteer-run initiatives like Soester Energie's. She said it would work with well-capitalised organisations that can raise financing more easily than a resident cooperative and that municipalities might favour it when assigning neighbourhoods. RTV Utrecht also reported the province's response: a spokesperson for energy deputy Huib van Essen said public and cooperative heat networks are both necessary and can coexist, and that a proposal is coming to Provincial States to clarify how support for each will work. The Utrechter Post has not independently verified either account.

For now, in Overhees, the case for cooperative heat networks is being made one warm winter at a time.