The Energy Performance of Buildings Directive (EPBD recast, 2010/31/EU) requires Member States to define minimum requirements of energy performance of buildings and building components with a view to achieving cost-optimal levels. In order to calculate the cost optimal level of minimum energy performance, Member States are required to create a set of reference buildings, at national or regional level, to be used in the calculations. This paper introduces to the concept of reference buildings and to the state of art at an international level. In particular, a general methodology for the creation of reference buildings is illustrated. A case study of an office building as a reference building for the Italian existing building stock is then shown. The process concerning the building definition and modeling was carried out by means of dynamic energy simulation program EnergyPlus. (c) 2012 Elsevier Ltd. All rights reserved.