The European Union considers climate change as the great- est long-term challenge facing the human race. It is therefore its priority to reduce the carbon dioxide concentrations, which are one of the main contributors to the climate change. The sustainability in the built environment is based on three pillars: sustainable materials and construction, sustainable energy use and waste management [1]. Public and commercial buildings in Europe consume an estimated 40% of the total energy [2]. It is impossible to improve this state without an energy efficient renovation of the existing buildings [3]. To achieve this objective and evaluate possible scenarios for intervention, it is necessary to document the existing situation in the building sector. For this reason, an extensive campaign in secondary school buildings of Cyprus is carried out. School buildings constitute a rather particular category of buildings. The running costs for heating, cooling and ventilation are the main costs in schools