Assembly comprising: - at least one structure provided with a peripheral wall and having at least one interior volume in which there is at least one of the following: -- a refrigerant fluid or a heat transfer fluid capable of circulating in said volume under the action of circulation means, -- elements (13, 130) for storing and releasing a thermal energy, -- at least one element (9, 100) to be maintained at a certain temperature, and/or -- at least one element releasing heat, - thermally insulating elements under vacuum and arranged around said peripheral wall, - at least some amongst retaining protrusions and retaining spacers, held opposite the peripheral wall, two protrusions or spacers defining between one another, laterally and around the peripheral wall, an open space in which the thermally insulating elements under vacuum are installed, and - a sleeve extending around the protrusions or spacers, and around the thermally insulating elements, so as to retain the latter in said open spaces extending between the sleeve and said peripheral wall, characterized in that: - the thermally insulating elements are contained in structures under vacuum, which are arranged in said open spaces and extend around said peripheral wall, and - said at least some protrusions and retaining spacers individually consist of several parts comprising: -- a first part for integrally fastening the peripheral wall, and -- a second removable part engaged with the first fastening part (22a; 111; 175, 1750) by cooperating shapes. - at least one structure provided with a peripheral wall and having at least one interior volume in which there is at least one of the following: -- a refrigerant fluid or a heat transfer fluid capable of circulating in said volume under the action of circulation means, -- elements (13, 130) for storing and releasing a thermal energy, -- at least one element (9, 100) to be maintained at a certain temperature, and/or -- at least one element releasing heat, -- a refrigerant fluid or a heat transfer fluid capable of circulating in said volume under the action of circulation means, -- elements (13, 130) for storing and releasing a thermal energy, -- at least one element (9, 100) to be maintained at a certain temperature, and/or -- at least one element releasing heat, - thermally insulating elements under vacuum and arranged around said peripheral wall, - at least some amongst retaining protrusions and retaining spacers, held opposite the peripheral wall, two protrusions or spacers defining between one another, laterally and around the peripheral wall, an open space in which the thermally insulating elements under vacuum are installed, and - a sleeve extending around the protrusions or spacers, and around the thermally insulating elements, so as to retain the latter in said open spaces extending between the sleeve and said peripheral wall, - the thermally insulating elements are contained in structures under vacuum, which are arranged in said open spaces and extend around said peripheral wall, and - said at least some protrusions and retaining spacers individually consist of several parts comprising: -- a first part for integrally fastening the peripheral wall, and -- a second removable part engaged with the first fastening part (22a; 111; 175, 1750) by cooperating shapes. -- a first part for integrally fastening the peripheral wall, and -- a second removable part engaged with the first fastening part (22a; 111; 175, 1750) by cooperating shapes.