FAQ - Ventilation of the building

Ground-coupled heat exchanger

The ground-coupled heat exchanger uses (in a passive way) geothermal energy, that is the energy of the ground.
The principle is to circulate the renewed air in a pipe that is about 2m down in the soil.

In summer the soil is at that depth colder than the outside air, which will help refresh the air before it is blown into the building. In winter it will be the opposite: the underground temperature is higher than the outside air and will be heated before getting into the house.

Ground-coupled heat exchanger or Energy Recovery ventilation (EVR)?

It is possible to combine both solutions. This combination reduces the energy needed for the heating in winter.

Illustration of Climamaison

- Ground coupled heat exchanger coupled with a EVR

Considering the cost (economic and ecological) of such a facility one should validate the appropriateness of this choice.

Especially as:

  • In summer the heat exchanger of the EVR will not be used as it would only increase the temperature of the provided air by the ground coupled heat-exchanger.
  • If the inter-seasons are mild, the air from the ground coupled heat-exchanger will be colder than the air outside, thus it will not be appropriate to bring it into the building. But to keep the ground coupled heat-exchanger in good condition it must be maintained in a minimum operation. The heat exchanger of the EVR will however gain a few degrees.
  • Only when the temperature will fall below 10 ° C the performance of this system will be enhanced.


If the location is known for long periods (inter-season) during which the outside temperature is close to the comfort temperature and the conception of the building in terms of insulation, exposure and management of solar contributions (in particular) is efficient;

And if one considers the installation and operating costs as well as the maintenance of an EVR together with a ground coupled heat-exchanger solution, they may be irrelevant, both financially and ecologically, in comparison to the generated energy savings.

Caution: this is not to exclude any particular solution, but to clarify the relevant issues. Even in the Mediterranean perimeter, such a scenario must be considered in terms of the specific microclimate and the location, orientation and topography of the site.

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Ventilation of the building

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