The energy renovation of existing buildings is an important tool for the reduction of energy consumption in the building sector, the improvement of prevailing indoor thermal comfort conditions and also for the improvement of environmental conditions in urban areas. At the same time, it is a technical, economic and social problem, due to the way in which many cities have been built and the restrictions imposed by economic constrains that tantalise most countries in South-Eastern Europe, and also Greece. It applies particularly in Nor-them Greece, with its cold and prolonged heating season, where a series of studies was carried out since 1994 to approach the problem and develop viable proposals. Public and mixed-use buildings form a significant part of the building stock and are therefore a primary candidate for energy saving measures, especially as they also play the role of a 'pilot-demonstrator' for the private owned buildings. However, due to the low energy prices that prevailed over the last 10 years, and as energy saving measurements are capital intensive investments, little was done in that direction. The recent sharp increase in oil prices proved that this was a short-sighted policy. In the following paper are presented the results of a study that aimed to determine the potential of energy saving renovation measures, in a representative sample of buildings under realistic conditions, to evaluate the feasibility of these measures, and also the way in which this feasibility is being analysed, under the rapidly changing economic conditions.