Cementitious composites integrated phase change materials for passive buildings: An overview

Phase change materials (PCMs) have attracted considerable attention as potential energy storage media for improving the energy storage densities of building envelopes. Therefore, researchers have committed to introducing PCMs into cementitious materials to develop structural–functional integrated thermal energy storage cementitious materials (TESCMs). Nevertheless, TESCMs have not been widely applied in large-scale engineering and remain in a trial or test stage. This review provides an overview of TESCMs for passive buildings to keep researchers abreast of the latest research trends and technological advances. Among the different types of PCMs, inorganic PCMs with low cost and high thermal conductivity have the most potential for application in buildings; however, their supercooling and phase separation must be addressed before use. Vacuum impregnation and micro-encapsulated and macro-encapsulated techniques are the main methods to encapsulate PCMs for preparing shape-stabilized PCMs (SSPCMs) and preventing PCM leakage from TESCMs. The inclusion of SSPCMs was found to have a negative effect on the workability, mechanical strength, and thermal conductivity of cementitious materials. However, thermal energy storage buildings (TESBs) composed of TESCMs can regulate the indoor temperature within the thermal comfort range, significantly decreasing energy consumption. This is because the effectiveness of TESBs depends highly on such factors as PCM dosages, climatic conditions, and the phase change temperature of PCMs; thus, a multi-objective optimization design is required to design TESB layouts.