Thermal insulating element

A panel-shaped insulating element for thermally insulating spaces, comprising a plurality of closed cells, wherein a first group of closed cells is formed by first recesses in a first flat element, and the first flat element between edges of openings of adjacent recesses forms first connection regions to which a first flat cover element closing the openings of the first recesses is materially bonded on a front side of the first flat element, characterized in that a second group of closed cells is provided, which is formed by second recesses in a second flat element, and the second flat element between edges of openings of adjacent recesses forms second connection regions to which a second flat cover element closing the openings of the second recesses is materially bonded on a front side of the second flat element, wherein the second recesses are provided on a rear side of the first flat element between the first recesses, and the first recesses are provided on a rear side of the second flat element between the second recesses, so that a volume remaining free of first and second recesses between the first and second flat elements is less than 50% of a volume enclosed by the first and second recesses together, wherein the first and second connecting regions are strip-shaped, forming a grid of strip-shaped connecting regions extending transversely at an angle of 90°, relative to one another, and bases of the first and second recesses are cross-shaped and the first recesses are arranged such that a cross-shaped base of the first recesses of the first flat element, over its entire length, rests on two intersecting strip-shaped connecting regions of the second flat element.