Back to school for our Geothermal Baskets

Promising results for the construction of this new-generation school building

The Var departmental council in south-east France embarked on the construction of a new-generation school building in 2017. A building meeting the highest energy performance standards, awarded the Gold-level Sustainable Mediterranean Building label and BBC Effinergie certification.


Project type: New build
Building type: Secondary school building
Construction time: 15 months
Year delivered: 2017
Net surface area: 7,655 m2
Cost of construction: €23,506,343
Proportion of geocooling cost: < 0.3%
Number of functional units: 700 students
Cost/m²: €3,071/m2

With the architectural expression making much use of wood, clay and other raw materials (steel and glass), photovoltaic energy production, a wood-fired boiler, a sun-breaker on the façade, green roofs, water recovery and reuse, geocooling i.e. geothermal technology used for cooling… a whole array of bioclimatic solutions were called on.

TERRENDIS ® geothermal baskets were selected as part of a collaborative effort bringing together our technical department and the project’s design office.

A horizontal geothermal system was initially planned using sensors placed in coils 0.90 metres deep, but it rapidly became apparent that there was not enough space for this solution.

The advantage of TERRENDIS® geothermal baskets is very simple: little space is required for optimal heat recovery, and they do not require any special technology to lay them.

Operation is just as simple: a heat transfer liquid recovers energy from the ground via a pipe; that energy is then converted by a geothermal heat pump using glycolated water or water on its own. Heating and cooling is then possible, via the ground, over the predefined surface area. Now, the project’s total cooling energy requirements are provided by the heat pump.


At the 4th Summer Comfort conference, held in 2018, José Coelho, Project Manager at the Oasiis design office, presented some initial feedback and measurements taken between March and June 2018 at the Collège Geneviève De Gaulle-Anthonioz school, which were very promising. Thanks to the sun-breakers, there were no reports of discomfort in spring and summer in the main teaching building. Temperatures remained below 26°C on the ground floor and first floor, even though the DTS had forecast over 100 hours above that threshold. On the second floor, the sub-breakers were effective and the skylights could be opened to let any heat out. It hadn’t been necessary to use the geocooling system, which meant the negative calories captured during winter could be stored for longer.

Number of baskets: 38 units

Power supplied: 42

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