The European and International Standard UNE-EN ISO 13790 presents a set of calculation methods for the evaluation and design of energy and thermal performance of buildings. These methods have diverse range of details for calculating the energy use of heating and cooling in different building zones, as well as for calculating the heat transfer and solar heat gains of special elements, such as ventilated solar walls (Trombe walls). In this article, the authors have revised the aforementioned document in order to check the proposed mathematical models and their implementation within Mediterranean climates. This assessment pinpoints the existence of some errors in the equations provided in EN ISO 13790 under steady state conditions. Concurrently, the corrected equations are shown and new correlations are proposed for the ratios delta and omega which are more suitable for Mediterranean climates. (C) 2009 Elsevier B.V. All rights reserved.