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This paper presents four mathematical models that have been developed to simulate the heat transfer between Phase Change Material and air to achieve behaviour analysis of those applications and their design analysis. These models have been validated through experimental results obtained in a previously constructed installation that tests Phase Change Materials performance. The storage procedure is macroencapsulation inside slabs. The four proposed models are: 1. Semi analytical model: this model is developed starting from the air-Phase Change Material heat transfer equation and eventually discretizing the system. 2. Finite differences 1 dimensional implicit model: as the thermal gradients inside the Phase Change Material parallel to the air flow direction are negligible compared to the ones in the perpendicular direction, a one-dimensional conduction model for the Phase Change Material has been considered. 3. Finite differences 2 dimensional implicit model: the two-dimensional heat conduction equation (perpendicular to the air flow (y-axis) and parallel (x-axis)) is numerically solved in the transient period to predict the temperatures distribution in the Phase Change Material. This model is particularly useful to analyze thick plates. 4. Fluid dynamic model: developing a fluid dynamic model the thermal behaviour of the whole system can be analyzed coupling two mathematical models: a model of phase change for the Phase Change Material within the slab and a fluid model for the heat thermal fluid circulating throughout the plate (2 dimension) or around the plate (3 dimension). Again the implicit formulation is used. The last three models incorporate the experimental enthalpy-temperature curves obtained for the Phase Change Materials in the laboratory by the T-history method. These Phase Change Materials are selected as their thermal window fits for building applications temperature ranges. Once the thermal behaviour of a single Phase Change Materials plate has been analyzed by all these models, the simulations results are compared to each other and finally to the experimental results with the purpose of finding the method with the best trade-off between accuracy and simplicity.