The present invention relates to a wall passage opening for passing a conduit through a through-penetration defining at least one reveal, of a building with a substantially vertical or horizontal orientation, wherein the conduit is covered with an insulation material (10) comprising an insulation shell (16), at least in the region of the passage opening, the diameter of the insulation element substantially corresponding to the inner diameter of the passage opening, wherein the insulation shell (16) includes a cavity for accommodating a conduit section (22) having an enlarged outer diameter and wherein the insulation shell (16) is made of mineral fibers, to accommodate the conduit section (22) having the enlarged outer diameter in a quick and easy manner.