Time evolution of energy use intensities and energy gap of existing Hellenic non-residential buildings

Abstract

This work exploits data from the energy performance certificates (EPCs) of the national electronic repository, to characterize the energy use intensity (EUI) of non-residential (NR) buildings in Greece and investigate the gap between the nominal needs and the actual energy use. Over the past eight years, a total of about 1,500,000 EPCs have been issued for various building types, out of which 17.5% for NR buildings. As the national EPC database is progressively enriched with more data, the work considers the time evolution of the average EUI and analyse the available data in order to determine whether they can be regarded as typical and representative for the Hellenic building stock. When available, data on actual energy use of the buildings is used in an attempt to close the gap between calculated (asset) and actual (operational) energy use. The data is organized in terms of different end uses and used to generate empirical correction factors that relate the normative calculated heating energy consumption with the actual energy use. These factors can be used to make more realistic estimates of the energy performance of buildings that undergo different refurbishments at national level.