Since 2008, the Spanish Structural Concrete Code (EHE in Spanish) has generally focused on respecting the environment; as a result, it has become a support tool for designing sustainable concrete structures. The Ministry of Public Works took charge of the initiative and a wide range of professionals and researchers, encompassing various points of view in this sector, carried it through. It is a pioneering initiative, opening up an avenue for the future of sustainable structural design. The purpose of this paper is to summarize the procedure used in drafting the sustainability appendix for the EHE and to present the EHE model for assessing the sustainability of concrete structures. Although the project has had its problems, the model that it produced is very thorough. It includes practically all the main criteria, taking into account the current state of the art and the fact that this was the first time a sustainability assessment technique has been included in a structural code.