•Analysis of heating consumption for existing school buildings.•Evaluation of energy performance for space heating.•Definition of energy retrofit strategies for heating in school buildings.•Economical evaluation of space heating retrofits. Improving the energy performance of public buildings is important for the promotion of a culture of energy efficiency among the local population. Indeed the European Union has developed strategies particularly for this sector using specific legislation and has targeted projects for economic support. In this paper we present a energy audit campaign conducted on 49 school building complexes located in the Lombardy region of Italy to collect data concerning their actual energy consumption for space heating, occupant behaviour and the technical characteristics of the buildings. On the basis of these data, different energy retrofit scenarios were studied with different performance and cost-effectiveness targets. The results show that it is not always convenient to improve excessively energy performance for heating.