Structural metal element for door-, window or the similar applications with improved thermal properties, having at least one interior surface, one exterior surface and one internal surface, where at least one surface of the element have improved optical properties by means of a surface treatment or coating. The surface in accordance with the invention has improved thermal emissivity and/or solar reflectance. Further, the invention also relates to a method of making the structural element, treated in a preferred manner or with preferred coatings.