Description of phase change materials (PCMs) used in buildings under various climates: A review

In the context of global warming, Phase change materials (PCMs) arise a growing interest in the scientific and industrial communities because it fits very well with the policy of reducing energy consumption that many countries must face. They are natural or synthetic substances with the peculiarity of storing and releasing thermal energy through their phase change. In the building sector, they can help regulate the temperature of rooms in which they are used. This article focuses on research mainly devoted to evaluating their thermal performance at a macroscopic scale. It proposes a presentation of the different concepts related to the PCMs and details the different types of PCMs studied according to the type of climate. Their behaviour under these various climatic conditions is also detailed and analysed. It then appears that some choices are made arbitrarily but often inadequately. It is also shown that there is no universal PCM at the scale of a single habitat, or efficient in all parts of the world. Then, the essential parameters necessary for choosing the PCM are revisited based on the compilation of data from the different articles. The value of combining PCMs with different characteristics is detailed, as is the need to have the suitable PCM in the right place in a habitat, coupled or not with an active heating or cooling system. Moreover, the analysis of the distribution of the studies on PCMs shows that they are not evenly distributed worldwide. The countries most concerned by global warming are not the most active, but rather those interested in increasing the comfort of their homes and/or who can afford the costs related to the corresponding research. Nevertheless, the scientific community is encouraged to take a broader interest in PCMs, as their application potential is very real, whether to reduce countries' energy dependence or provide relevant technical and scientific assistance to developing countries.