In Sablet, Vaucluse, an elementary school is a pioneer in low-carbon heating. The municipality opted for an innovative, environmentally-friendly solution to replace its old oil-fired boiler, demonstrating its commitment to the energy transition as well as to reducing infrastructure heating costs.
The Sablet school, which dates back to the 1950s, was in need of complete renovation, particularly in terms of insulation and heating system. The town council undertook a major project to improve the energy efficiency of the 850 m² building.
Before tackling the heating system, the municipality completely insulated part of the building, including the motor room. This crucial step considerably reduced the facility's energy requirements.
After studying several options, including wood cogeneration, gas and aerothermal heating, the town council finally opted for a low-carbon heating system based on geothermal energy. This solution combines a reversible water/water heat pump (PAC) with a vertical geothermal probe field.
The choice fell on a GeoTwin 4 PAC from French manufacturer ARKTEOS, with an output of 52 kW. This low-carbon heating system covers 96% of the school's heating needs, considerably reducing CO2 emissions.
Low-carbon geothermal heating offers many advantages:
- Reduction in CO2 emissions: Sablet town council expects to reduce its emissions from 30 tonnes to just 5 tonnes per year.
- Energy savings: The return on investment is estimated at six to seven years.
- Thermal comfort: The system provides both heating in winter and cooling in summer.
- Durability: Geothermal probes have a 50-year guarantee and a minimum lifespan of 100 years.
The low-carbon heating system installed at the Sablet school is based on harnessing heat from underground. Here are the main components of the system:
Vertical geothermal probes: 9 Terra Extrem Neo probes from Elydan were installed at a depth of 140 m. These probes capture heat from the ground. These probes capture heat from the ground.
Heat pump: Arktéos' GeoTwin 4 heat pump transfers the heat captured by the probes to the school's distribution system.
Fan coil units: 15 units from Italian manufacturer Sabiana were installed in the ceiling of each room to distribute heat or cold.
Back-up system: A small 30 kW Viessmann oil-fired boiler provides back-up in the event of a heat pump failure.
A geothermal (water-to-water) heat pump works by harnessing the heat of the subsoil. Here are the main stages in its operation:
♨️ Heat capture: A heat transfer fluid circulates through vertical geothermal probes installed in the ground, absorbing the earth's natural heat.
️ Heat transfer: The heat transfer fluid, heated by the ground, is pumped to the heat pump.
➕ Amplification: The heat pump, using a thermodynamic cycle, amplifies the heat captured to reach a higher temperature.
🔀 Distribution: The amplified heat is transferred to the building's heating system, usually via a network of fan coil units or underfloor heating.
❄️ Reverse cycle: In summer, the system can operate in cooling mode by reversing the cycle, extracting heat from the building and releasing it into the ground.
Although not used in the Sablet project, it's worth mentioning another low-carbon geothermal heating technique: the basket system. This system operates on the same principle as vertical probes, but uses basket-shaped heat exchangers installed horizontally at shallow depths (around 3 to 5 meters).
- Less expensive to install than deep drilling
- Suitable for sites where deep drilling is not possible
- Larger footprint, but ideal for larger sites
Operation is similar to that of vertical probes: a heat transfer fluid circulates through the baskets, capturing heat from the ground, then transferring it to a heat pump which amplifies it to heat the building.
Implementing a low-carbon heating system like the one at Sablet school presents certain challenges:
- High initial cost: The total cost of the project amounts to 267,800 euros, including project management, drilling work, HVAC installation and electrical connection.
- Technical complexity: Installation requires the intervention of specialized professionals, such as SARL Anaya Crueize, which won the HVAC tender.
- Rigorous planning: the work had to be carried out in several phases, mainly during school vacations, to minimize disruption.
Le chauffage bas carbone par géothermie installé à l’école de Sablet illustre parfaitement les possibilités offertes par les technologies modernes pour réduire l’empreinte carbone des bâtiments.
Cette solution combine efficacité énergétique, confort thermique et respect de l’environnement.
Alors que la lutte contre le changement climatique s’intensifie, le chauffage bas carbone apparaît comme une solution d’avenir pour les bâtiments publics et privés. L’exemple de Sablet montre que, grâce aux aides financières et à l’expertise d’entreprises spécialisées, ces technologies sont désormais accessibles et peuvent être déployées à grande échelle, dans une large typologie de constructions.
Le succès de ce projet de chauffage bas carbone ouvre la voie à une généralisation de ces solutions, contribuant ainsi à la transition énergétique et à la réduction des émissions de gaz à effet de serre dans le secteur du bâtiment.
Depuis 2025, le Groupe Elydan propose des services de forages d’eau et de forages géothermiques via sa filiale Geo Connect Energies. Cette proposition de services a été rendue possible dans le cadre de la création d’Endralis, filiale du Goupe Elydan dédiée aux réseaux de chaleur et Énergies Renouvelables.
Sur le site web geoconnectenergies.com, retrouvez également une liste de produits et matériels sur mesure, ainsi que tous vos contacts pour vous aidez à bâtir des projets de réseaux de chaleur géothermique !
Lire ici notre retour d’expérience sur l’installation d’un système de chauffage alimenté par des sondes géothermiques Elydan, au Mémorial National Australien Sir John Monash, à Fouilloy dans la Somme.
