This paper presents a detailed method to develop cost-optimal studies for the energy renovation of residential buildings. A realistic characterization of the building has been introduced, using measurement and survey data. The method allows improving the interaction between the occupancy and the building, and the characterization of the real state of the construction. In addition, the building simulation includes vernacular strategies of the Mediterranean architecture, as for example the natural ventilation and the use of solar protection. The method presented takes part of an innovative approach: two-step evaluation considering thermal comfort, energy and ecohomic criteria. The passive evaluation is the focus of the paper and evaluates the passive measures from an economic and thermal comfort point of view. This method prioritizes the passive measures rather than the active ones, considering the thermal comfort of the users as a criterion of decision. The paper shows the results of a multi-family building built in the years 1990-2007 and located in two climates C2 and B3 (Barcelona and Tarragona). The method provides technical and economic information about a set of passive energy efficiency measures, with the objective to help to make decisions for choosing the appropriate combination of passive measures. (C) 2015 Elsevier B.V. All rights reserved.