A Review on the Utilisation of Phase Changing Materials in Passive Buildings: A Comparison with Common Thermal Mass

Adding thermal mass to store the heat is an important aspect of passive building design. Despite the proven benefits of conventional materials with high thermal mass, they have disadvantages. In the first part, this paper discusses the weaknesses of conventional materials with high thermal mass in buildings, including their weight, lack of control over their function, and high embodied energy and emissions throughout the life of buildings. The second part discusses the possibility of using phase changing materials (PCMs) to overcome those weaknesses. The results show that PCMs are considerably lighter and can be placed on ceilings and walls without additional structural load. PCMs also provide more control as they come with different melting points, which can be used for the benefit of the design. There are some uncertainties about the lifecycle analysis of PCMs due to the lack of comprehensive research in this area, especially regarding the encapsulation process. However, the existing data suggest some reduction in embodied energy and emissions over conventional thermal mass.