Residential buildings are the vast majority of the building sector and play a significant role in the energy and environmental footprint of the whole building stock. This paper presents an overview of the energy performance of the existing Hellenic residential building stock, by exploiting data from the EPCs (energy performance certificates) of buildings issued in accordance to national EPBD (energy performance in buildings directive) provisions. The analysis is performed for different building size (i.e. single- and multi-family houses), construction periods and locations (i.e. at the four national climate zones). In addition, implemented energy conservation measures are investigated in order to define the most common refurbishment actions for each building type. According to 650,000 EPCs that have been issued in Greece by August 2015,15% are for single-family houses and 85% for multi-family houses (buildings or building units). About 34% of the residential buildings are ranked at the lowest energy class-G, while only 3% are ranked in energy class-B or higher. The average calculated primary energy is 261.6kWh/m(2) and the average CO2 emissions 70.3 kg/m(2). Replacing the windows is the most popular retrofit action, followed by the installation of solar collectors for domestic hot water. (C) 2016 Elsevier Ltd. All rights reserved.