Thermal energy conservation and management is a key issue for energy savings in any field with intensive thermal
dem ands. One of these fields is the building sector , which nowadays accounts for 40% of the European energy
co nsumption. There are many technolog ies in the building sector where the presence of thermal energy storage
imply a more efficient and profitable operation. Amongst th ese technologies, one can found thermal solar systems,
residential cogeneration, etc., where usually conventional hot water tanks are included in order to couple the
generation and the demand. However, these tanks require big water volumes and high aspect ratios, which can be a
problem in domestic applications where there is usually a lack of space.
This can be avoided by Phase Change Materials (PCMs) , which use the latent thermal exchange taking place during
th e liquid- solid phase change as the thermal storage mechanism allowing a higher thermal storage density [1].
However, it should be considered that PCMs pr esen t some disadvantages over conventional Thermal Energy
Storage ( TES ) systems. They generally present low thermal conductivities (between 0.2 and 0.7 W/m· K), which
redu ce the effective power in the charging and release of the thermal en ergy . Moreover, the specific price of these
systems is significantly higher. Therefore, the designer plays a very important role based on the two main following
considerations: