The objective of this research is to identify a tool of analysis applicable to school buildings that, through simple input information, can make immediate assessment reduction of energy consumption for heating and associated reduction of CO2emission, as a result of improvements. The definition of a methodology of analysis allows to evaluate preliminarily the energy performance of the whole school building identifying the most problematic buildings and dividing into groups based on the construction and geometry. In the first phaseall buildings have been filed through information obtained from survey and documentation of archives, then two analyses were performed to compare the energy performance of the whole sample. For the initial analysis it was applied a methodology proposed by ENEA (Italian National Agency for New Technologies, Energy and Sustainable Economic Development) and designed specifically for school buildings; in the second analysis it was calculated the energy performance index for winter heating and compared with the appropriate limit value. Subsequently a sample of buildings was well selectedafter splitting the school building into homogeneous groups. The buildings have been translated into a mathematical model of the building system calibrated on actual energy consumption and dynamic conditions were simulated in order to accurately quantify the impact of the various proposed actions. The results of all combinations of intervention, obtained from the latter analysis, have been used to develop a tool that identified the type of building and construction technology in order to estimate the immediate reduction of consumption and the CO2 emitted. The methodology was applied to the school building of the municipality of Castelfranco Veneto, simulating two scenarios: the first plan to interventions under the PAES (Action Plan for Sustainable Energy) for public buildings while the second considers the possibility of performing all the improvements recommended by the instrument in relation to the entire academic heritage of the city.