In Italy, most public buildings, and especially the educational ones, lack a proper design to guarantee sustainable thermal comfort conditions in the cooling season. However, due to the frequently more extended use of school buildings in the summer months and the warm temperature conditions, widespread indoor thermal discomfort is often experienced, with negative impacts on children’s and students’ learning performance. Consequently, the need to guarantee adequate indoor environmental conditions in schools in the summer season is becoming prominent for several public administrations. In this context, this study aims at the identification of solutions and strategies for the optimization of energy performance and indoor thermal comfort of public school buildings during the cooling season. To reach this goal, two case-study public school buildings set in Bolzano, Italy, were analysed and compared. Results proved the importance of passive and semi-passive cooling strategies in optimizing indoor thermal comfort, especially in the mid-seasons, and the need for mechanical cooling and ventilation systems to guarantee adequate levels of indoor environmental quality and schoolwork performance in the warmest months.