In this paper, the latest progress in Turkey towards Recast Directive on Energy Performance of Buildings (EPBD Recast) targets is explained. In addition, sample calculations oriented at cost optimal retrofit analysis of an existing apartment building are also presented. In order to give an initial point of view about cost optimality concept and retrofit strategies in Mediterranean climate, an apartment building is analyzed for hot humid and mild climatic regions. The scenarios which are able to represent cost optimal level are highlighted and key aspects are derived for the nZEB approach in Mediterranean climate. (C) 2015 The Authors. Published by Elsevier Ltd.