Method for constructing or altering a matter- and/or heat-exchange device, wherein the mass- and/or heat-exchange device is assembled by using at least one first and one second stackable modular element (10, 11, 11a, 11b, 11c, 12, 12a, 12b, 12c, 13, 20, 21, 22, 22a, 22b, 23, 23a, 23b, 24, 31, 31a, 31b, 32, 32a, 32b, 33, 41, 42, 43, 44, 45, 46, 47, 48, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P), each of the first and second elements comprising a parallelepiped box having a length, a width and a height, the box having an upper face and a lower face, horizontally opposite, two front faces, vertically opposite, as well as two side faces, vertically opposite, the upper and lower faces of the box being defined by the length and the width of the box, the two front faces of the box by the length and the height of the box and the two side faces of the box by the width and the height of the box, the box containing at least one thermal insulating layer, the insulating layer covering at least the side and front faces of the box and optionally the upper and lower faces and surrounding at least one chamber with parallelepiped volume inside the box, the at least one chamber having a length, a width and a height, the chamber having an upper face and a lower face, horizontally opposite, the upper face and/or the lower face of the chamber being at least partially open, two front faces, vertically opposite, as well as two side faces, vertically opposite, the upper and lower faces of the chamber being defined by the length and the width of the chamber, the two front faces of the chamber by the length and the height of the chamber and the two side faces of the chamber by the width and the height of the chamber, the chamber containing at least one matter body allowing the exchange of mass and/or of heat, the body being of parallelepiped shape and filling at least one portion of the chamber, wherein i) the thermal insulating layer has a thickness less than one third of the width of the box, and ii) the first element having the at least one chamber having an opening on the lower face communicating with an opening in the lower face of the box and the second element having the at least one chamber have an opening on the upper face communicating with an opening in the upper face of the box for allowing the transfer of fluid from the body of the first element towards the body of the second element and/or from the second element towards the body of the first element and that, according to the method a) the first element is fixed on the second element or the second element is fixed under the first element in a sealed manner, such that a fluid can pass from the body of the first element towards the body of the second element and/or from the body of the second element towards the body of the first element, and/or b) the first element is disconnected from the second element, above which it is fixed in a sealed manner or the second element is disconnected from the first element below which it is fixed in a sealed manner, such that a fluid can pass from the body of the first element towards the body of the second element and/or from the second element towards the body of the first element. i) the thermal insulating layer has a thickness less than one third of the width of the box, and ii) the first element having the at least one chamber having an opening on the lower face communicating with an opening in the lower face of the box and the second element having the at least one chamber have an opening on the upper face communicating with an opening in the upper face of the box for allowing the transfer of fluid from the body of the first element towards the body of the second element and/or from the second element towards the body of the first element and that, according to the method a) the first element is fixed on the second element or the second element is fixed under the first element in a sealed manner, such that a fluid can pass from the body of the first element towards the body of the second element and/or from the body of the second element towards the body of the first element, and/or b) the first element is disconnected from the second element, above which it is fixed in a sealed manner or the second element is disconnected from the first element below which it is fixed in a sealed manner, such that a fluid can pass from the body of the first element towards the body of the second element and/or from the second element towards the body of the first element. a) the first element is fixed on the second element or the second element is fixed under the first element in a sealed manner, such that a fluid can pass from the body of the first element towards the body of the second element and/or from the body of the second element towards the body of the first element, and/or b) the first element is disconnected from the second element, above which it is fixed in a sealed manner or the second element is disconnected from the first element below which it is fixed in a sealed manner, such that a fluid can pass from the body of the first element towards the body of the second element and/or from the second element towards the body of the first element.