Abstract With reference to building applications, recent scientific literature shows good potential in reducing cooling loads by means of phase change materials (PCMs), integrated in the building exterior envelope. This paper proposes a deepening, by investigating if these dynamic components could contribute in reducing building cooling demand in Mediterranean climates. An office building is analyzed, with reference to the entire cooling season (from May 1st to September 30th), in reliable conditions as regards building use, and thus internal gains, occupancy, activation of cooling systems. More in detail, through hourly energy simulation, the achievable cooling energy savings have been calculated, with reference to a well-insulated massive building, refurbished by means of addition of PCM plaster on the inner side of the exterior envelope. Five Mediterranean climates have been taken into account: Ankara (Turkey), Athens (Greece), Naples (Italy), Marseille (France), Seville (Spain). The studies regarded the influences of the phase change temperature, thickness of the PCM wallboard and location of the PCM layer. Beyond the evaluation of the absolute savings of primary energy requests for cooling, the energy saving rate and the not-overheating time have been calculated, respectively by considering an air conditioned building and a naturally ventilated building with free-running indoor temperatures. Starting from the achieved results, through the values of the proposed indicators, this paper would suggest information useful for proper design and selection of phase change materials for building applications.