Energy efficiency is very important in school buildings as it is associated with comfort and air quality conditions in their interior and energy costs of these buildings are associated with their main operational costs. Moreover, school buildings differ from other types of buildings because they are the places where children are educated and have the opportunity to learn how to become environmentally-aware citizens. There is an increasing awareness throughout Europe for promotion of sustainable solutions in school buildings involving energy efficient technologies and measures. The aim of this article is to assess the energy performance, based on monitored data, of school buildings in the C climatic zone of Greece, a region with the lowest air temperature during winter period. It also demonstrates, through simulation studies, the potential for energy conservation of school buildings in this region. (C) 2008 Elsevier Ltd. All rights reserved.