An optical element (11) in the form of an at least partially transparent face comprises transparent areas and essentially non-transparent areas. The transparent areas are arranged sufficiently close for the intermediate and essentially non-transparent areas to be essentially invisible to the naked eye, at least when the element is viewed from a given distance. The essentially non-transparent areas are arranged sufficiently close and have a sufficient extent at right angles to the face for the intermediate, transparent areas to have such depth/width ratio that the optical element will, at a given point on the face, allow passage of light with given angles of incidence, while light having other angles of incidence are unable to pass the element at the point in question. Hereby an optical element is obtained that is able to better reduce the heating of the interior of a building that is caused by incoming solar radiation without the direct radiation and hence the view being blocked considerably.