An assembly comprising: - a plurality of first pockets (3;3a,3b,3c) containing at least one thermally insulating material and in which a first controlled atmosphere prevails, the or each thermally insulating material having open cells with a diameter greater than or equal to 1 micron, - at least one second pocket (7;7a,7b,7c): -- which surrounds the first pockets (3;3a,3b,3c), -- in which a second controlled atmosphere prevails, and -- which forms an intermediate part, between two successive first pockets that the intermediate part joins together, characterized in that: - the or each said intermediate part is adapted to allow said pockets to be hinged with respect to one another, - the second pocket (7; 7a,7b,7c), of which there is only one, and which is peripherally closed at a location of a minor peripheral surface, continuously extends around all the first pockets (3;3a,3b,3c) at locations of respective major surfaces, up to the minor peripheral surface, - on at least a main part of said respective minor and major surfaces, the respective second pocket and first pockets are: -- applied against one another in pairs, or -- separated by an empty space, which thus includes no material. - a plurality of first pockets (3;3a,3b,3c) containing at least one thermally insulating material and in which a first controlled atmosphere prevails, the or each thermally insulating material having open cells with a diameter greater than or equal to 1 micron, - at least one second pocket (7;7a,7b,7c): -- which surrounds the first pockets (3;3a,3b,3c), -- in which a second controlled atmosphere prevails, and -- which forms an intermediate part, between two successive first pockets that the intermediate part joins together, characterized in that: - the or each said intermediate part is adapted to allow said pockets to be hinged with respect to one another, - the second pocket (7; 7a,7b,7c), of which there is only one, and which is peripherally closed at a location of a minor peripheral surface, continuously extends around all the first pockets (3;3a,3b,3c) at locations of respective major surfaces, up to the minor peripheral surface, - on at least a main part of said respective minor and major surfaces, the respective second pocket and first pockets are: -- applied against one another in pairs, or -- separated by an empty space, which thus includes no material. -- which surrounds the first pockets (3;3a,3b,3c), -- in which a second controlled atmosphere prevails, and -- which forms an intermediate part, between two successive first pockets that the intermediate part joins together, - the or each said intermediate part is adapted to allow said pockets to be hinged with respect to one another, - the second pocket (7; 7a,7b,7c), of which there is only one, and which is peripherally closed at a location of a minor peripheral surface, continuously extends around all the first pockets (3;3a,3b,3c) at locations of respective major surfaces, up to the minor peripheral surface, - on at least a main part of said respective minor and major surfaces, the respective second pocket and first pockets are: -- applied against one another in pairs, or -- separated by an empty space, which thus includes no material. -- applied against one another in pairs, or -- separated by an empty space, which thus includes no material.