- 1,700 kW heat output
- 3,400 MWh/a energy for space heating and hot water
- 70,000 litres energy storage
- 92 kWp PV output
Gemeindewerke Villmergen (GWV) was commissioned to progress the takeover and expansion of an existing heating network. As it had no experience with operating a network of this size, it sought an independent partner with the necessary expertise. An important criterion was that the partner had experts who could carry out a comprehensive cost-effectiveness analysis of the planned heating network. The network should be self-sustaining, with no need for cross-subsidisation by taxpayers. In its search for the right partner, GWV contacted ewz, among others. The energy service provider had been working with GWV in power supply for many years. GWV therefore knew that ewz also had a great deal of expertise in the development and operation of new heating networks throughout Switzerland. The talks went well, and the two companies were able to reach an agreement quickly following a joint feasibility study.
The collaboration between GWV and ewz does not follow the traditional client-contractor approach, but is based on a cooperation model. This model provides for joint planning, implementation and operation, with each partner contributing where its strengths lie. Given its extensive experience, ewz is assuming responsibility for the planning and operation of the energy centre. ewz is renting the building itself from GWV, but is independently financing and implementing the technical infrastructure for heat generation.
Public involvement
It was important to both partners to actively involve the local population. That’s why they held information events back in summer 2022 at which the project was presented in detail and attendees had the opportunity to ask questions and provide feedback. The technical and financial aspects of the project were then discussed at two municipal assemblies, and the green light was finally given for implementation. Once detailed plans had been drawn up and building permits obtained, the groundbreaking ceremony for the initial construction stage took place in April 2025. Official commissioning is scheduled for April 2026.
ewz will sell the heat generated to GWV, which, with its experience in civil engineering and its local roots, will be responsible for expanding and operating the heating network as well as for acquiring and supporting end customers. ewz could also provide these services itself, but experience with similar projects shows that a local partner increases acceptance among the population. This often makes it easier and quicker to implement district heating projects. GWV in turn will benefit from the cooperation because its employees will be able to gain valuable experience and build up expertise in heat supply.
The tasks and interfaces are laid down in a contract. However, this does not mean that the two companies are acting in isolation from each other. Instead, the project teams regularly exchange ideas and carry out certain tasks together, such as informing the public. Representatives of both companies are always involved in those events.
Climate-friendly energy source
GWV and ewz worked on the plans for the expansion of the heating network together. The first step was to clarify which supplementary energy sources were available in the locality to supply a larger network area. Although groundwater was discarded as an energy source because it was not abundant enough at the site, a suitable alternative could be found in the form of a larger wood chip furnace. This solution is also financially attractive for the municipality because it can use timber from its own forestry operation. The next step was to ascertain which building owners were interested in connecting their properties and, based on the feedback, to define the appropriate perimeter for the expanded heating network. The feasibility analysis revealed that an expansion of the heating network was economically and technically feasible.
Phased expansion
The dimensions of the heat generation will be tailored to the expansion of the network. During the first stage, two school buildings with a sports hall, eight apartment buildings with a total of around 60 apartments, three single-family homes and three commercial properties are being connected to the heating network. A small wood-fired boiler has been installed in the energy centre for this purpose. It is likely to be supplemented by a more powerful boiler in five years’ time, when the demand for heating is higher due to the connection of further properties as well as school buildings owned by the municipality. This phased expansion of the heat generation will ensure that investments are only made as and when corresponding energy sales are secured.
Automated chip store
The energy centre includes several innovative technical solutions, among them the wood chip store. Normally, wood chips are stored in an underground chip silo, but this was not possible in Villmergen due to the groundwater level. Instead, the chips are being delivered to a ground-level hall. So that the chips do not have to be repeatedly pushed back manually for onward transport to the boiler, ewz has opted for an automated alternative. It combines a screen operating from above – a top-loader system – with a short sliding floor and a cross conveyor. This will ensure that no old chips are left behind. The effort required to manage the store will be significantly reduced and the boiler will be supplied reliably.
Efficient operation
The boiler itself has a combustion air pre-heating system. The incoming fresh air absorbs heat from the hot exhaust gases from the combustion process. This heating will enable the boiler to run at a lower output in summer during partial-load operation, allowing it to be operated more consistently and with less impact on the environment.
The exhaust gases from the combustion process are trapped by modern filters. The system includes an e-filter that automatically separates particulate matter electrostatically. This ensures high air quality. The small wood-fired boiler in the energy centre and the first line of the heating network were put into operation in March 2026. Regular operation has been scheduled for April 2026.
© Header image photo: Gemeindewerke Villmergen
