A new geothermal heating system reduces the energy consumption of a residence in Gex by a factor of four

Thanks to this exemplary project, initiated in May 2022, residents now benefit from an optimized heating system with -76% energy consumption, guaranteeing increased living comfort and a significant reduction in costs.

From an energy-guzzling 60s residence to a model of energy efficiency

Built in 1960, this residence of 61 apartments spread across three buildings (4,300 m²) faced challenges typical of the French housing stock: aging gas boilers, high energy costs, and a significant carbon footprint. Having already installed exterior insulation in 2014, the condominium association was looking for a more environmentally friendly heating solution capable of sustainably reducing costs while ensuring residents' comfort.

Geothermal energy, an innovative technical solution

Initiated by the president of the condominium board, managed by the property management company Foncia and brought to fruition by Accenta's technical and economic expertise, this innovative project combines several complementary technologies:

• 17 geothermal probes, each 200 meters deep,
• Two geothermal heat pumps providing the majority of the energy production, Solar thermal panels installed on the roof,
• 3 cascaded gas boilers for optimal backup (9% of production),
• A control system based on learning and predictive regulation that optimizes the system's operation in real time.

This hybrid installation makes it possible to make the most of each energy source, prioritizing renewable energies and only using gas as a backup when necessary, very occasionally.

A 30-year energy performance contract

Beyond its technical achievement, this project stands out for its innovative business model. Thanks to a 30-year energy performance contract (EPC), Accenta guarantees the promised savings and allows for financing over 25 years. This model perfectly aligns with Foncia's ambitions, as it makes investment accessible to co-ownership associations.

The expected results demonstrate the effectiveness of the system:

• – 76% energy consumption
• – 91% reduction in CO₂ emissions

According to Jean Wimmer, Sales Director for Housing & Communities at Accenta: “This project perfectly illustrates our approach: offering high-performance technical solutions while guaranteeing their long-term profitability. Thanks to the CPE*, co-ownerships no longer have to advance considerable funds and benefit from a guarantee of results. This is a paradigm shift in energy renovation.”

A replicable model for energy renovation

According to Thierry Reinheis, director of condominium management at Foncia Lémanique: “As part of this large-scale project, Foncia ensured rigorous coordination of all phases, supporting the co-owners from the initial discussions to the completion of the construction. The close collaboration between the management committee, Accenta, and Foncia is central to the success of this project. Thanks to this collaborative work, all residents can now benefit from a significant and lasting 76% reduction in their energy bills.”

According to Patrick Dutruel, president of the Foncia Bassin Lémanique metropolitan area: “In the Lake Geneva region, we are driving a strong momentum in energy-efficient renovations of condominiums, with around ten major projects currently underway. A symbol of innovation, this project, which utilizes geothermal energy, is a first for a condominium of this size in the region. It demonstrates the commitment of Foncia's teams to protecting residents' purchasing power and enhancing the value of their properties, while providing innovative and sustainable solutions to all the condominiums we support.”

With 780.000 co-owned properties in France, more than half of which were built before 1974, the potential for replicating this type of project is significant. Buildings 5, 6, and 7 of the Les Vertes Campagnes complex thus become a concrete example for all co-owned properties wishing to commit to the energy transition without compromising their financial stability.

*Energy Performance Contract