The Energy Performance of Buildings Directive (EPBD) is an important European policy tool to improve energy performance of buildings and has been applied in 27 countries with specific adjustments. The aim of this paper is to analyze the application of the Portuguese energy certification system and regulation to the residential sector using a case type, whilst considering a set of alternative and complementary solutions involving the regulation values for the envelope, interior and exterior thermal insulation, lower air renovation ratio, light colored exterior walls, better glazing system, shading elements and a Trombe Wall. In order to understand the role and the importance of bioclimatic measures in the Portuguese application of the EPBD, a comparison with the Passivhaus Norm applied to warm countries in Europe will be made. Due to the diversity of the Portuguese climate, three different climate regions were considered. Finally, we will discuss what new measures should be added to the Portuguese regulation, so that the proposed recast of the Directive might be transformed into a more effective tool in the search for better energy performance, passive house buildings and sustainable constructions. (C) 2011 Elsevier Ltd. All rights reserved.