In recent decades, the energy conservation in buildings have attracted a broad spectrum of researchers’ interest in building and energy-related fields. Enhancement of energy efficiency and utilization of renewable energy are the most prevalent solutions for energy conservation in buildings. The application of phase change materials in the construction of building materials and building elements, which results in an increase in the thermal mass and thermal inertia of buildings, is one of the most recent methods of increasing energy efficiency of buildings. In this study, thermal performance and thermal energy storage (TES) capability of precast concrete sandwich panel wall specimens incorporating PCMs made out of normalweight and structural lightweight concrete were investigated. The total thickness of the specimens was 10 or 15 cm and the thickness of the macro encapsulated PCM layer was 1.5 or 2 cm. PEG 600 and a kind of salt hydrate are used as the PCM. The specimens were tested under the weather temperature condition of a summer day of Ardebil, Kashan and Ahwaz cities. For thermal performance test of specimens, an innovative experimental setup called “Daily Temperature Simulator” was employed and the maximum reduction of inner side temperature and the reduction of ultimate inner side temperature and time delay to reach to the maximum temperature were measured as the thermal performance criteria. Furthermore, the charge/discharge process of the PCM during a complete day was evaluated. Results stated that the application of phase change materials in concrete walls would reduce the inner side temperature of the wall up to 5.4 °C and up to 6 hour shift in peak load with respect to the specimen and applied temperature condition. Keywords : Concrete, Phase change material (PCM), Solar Energy, Daily temperature simulator apparatus, Thermal performance.