The increasing gas emissions and the continuous rise of fuel prices are the main reasons why new solutions for world energy demand are searched. Using Europe as an indicator, every year more than thirty per cent of the oil demand in Europe is used in the private and commercial sector. From this approach, it is clear that reducing heat losses of buildings or, in general, their heat energy consumption will have a major impact on the total emissions in Europe and in the rest of world. This project focused on the desire of finding renewable sources of energy which will replace the harmful and limited fossils fuels and the low effective electricity in building heating systems. Besides, its aim was to enhance the energy efficiency of power systems. One option to improve energy efficiency is to develop energy storage devices and systems in order to reduce the mismatch between supply and demand. The different forms in which energy can be stored are mechanical, electrical and thermal. In this project, only thermal energy storage was considered and therefore, the latent heat discussed but neither the sensible and the thermochemical heats were considered. The latent heat storage is produced when a material undergoes a phase change from solid to liquid, liquid to gas, or the reverse. Its main advantages are the high energy density that can be stored, and that it is possible to store energy at a constant temperature or in a really short range of temperatures. This value of temperature corresponds to the phase transition temperature of the material. Nowadays, phase change materials have been used to enhance gypsum wallboards or concrete in building applications, but in this cases the phase change material remains in stationary conditions without flowing. Moreover, there are similar solar storage energy systems for building heating applications which use water. The main improvement carried out in this project was to use a phase change material mixed with water and let it flow all around the thermal circuit as if it was only water. This led to greater heat storage capacity per unit volume than water. Therefore, in this work, an overview is given on how a thermosolar energy system for a building can be implanted using the latent heat of a phase change material.