NOVELTY - The enclosure (1) has a pocket (11) made of deformable material and equipped in a terrestrial basement (6), where an expansion unit allows variations of volume of contents of the enclosure that is filled with another deformable material. An expansion vessel (3) is hydraulically connected to the pocket by a pipe (4). The former deformable material is a flexible plastic material i.e. polyethylene. The latter deformable material is a mixture of glycol, water and minerals e.g. sand. A sealing unit is placed on a level of an opening (5) and/or on a level of another pipe (7).    USE - Enclosure for enclosing a geothermal exchanger device i.e. low energy geothermal exchanger device, of a thermodynamic machine (all claimed) to condition i.e. heat and/or cool, a building. Uses include but are not limited to individual residential building, collective residential building, tertiary building, commercial building and industrial building.    ADVANTAGE - The sealing unit is placed on the level of the opening and/or on the level of the pipe, so that the enclosure is preferably sealed. The pocket is dimensioned such that the totality of the geothermal exchanger is contained in the pocket. The pocket is small in size, and has high conductivity and heat capacity, so that the heat exchange between the geothermal exchanger and the terrestrial basement is improved. The pocket is filled with the filling material having high conductivity and heat capacity in order to maximize the transmissible heat flux between the terrestrial basement and the geothermic exchanger. The geothermal exchanger guarantees better contact with the terrestrial basement under all conditions. The expansion vessel has capacity of 20 liters to compensate the variations of the volume of the pocket due to freeze/thaw.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a thermodynamic machine, comprising a condenser.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of a geothermal exchanger device.    Enclosure (1)    Expansion vessel (3)    Pipes (4, 7)    Opening (5)    Terrestrial basement (6)    Pocket (11)