Graphical abstract Display Omitted

Highlights • Different incorporation techniques of PCMs in building envelopes are presented. • The synthesis processes of different microencapsulation methods were discussed. • The effect of PCM incorporation on heat transfer and energy consumption of buildings is also analyzed. • Economic benefits and CO2 emission reduction through the incorporation of PCMs in buildings are presented. • The future research possibilities for the PCM embedded buildings are also outlined.

Abstract The urbanization and comfort in the living standards of human beings have shown a tremendous increase in the energy demand around the globe. The building sector is one of the major sectors which consumes about 40% of the overall energy consumption which has led to environmental impacts. Most of the energy required for the building sectors is used for its heating and cooling in order to achieve the desired level of thermal comfort. Therefore, one of the primitive challenges for researchers is to reduce energy usage without compromising the building's thermal comfort. The phase change material (PCM) has a significant potential to store and release the heat for energy conservation and thermal regulation process. The use of PCMs in building construction is an emerging technology that offers considerable cooling and heating of buildings leading to thermal comfort with reduced energy consumption. To meet these challenges, an extensive review has been conducted in the present study to evaluate the effect of PCM integrated into the building envelopes. Further, the selection of PCM and different techniques for its incorporation in the building envelopes are presented. Energy savings and economic benefits obtained through the integration of PCM in building materials are also discussed. Based on the study, it is concluded that the reduction in energy consumption and improved thermal comfort is achieved using the PCM in building envelopes such as walls, roofs, ceilings, and windows. Among the studied incorporation techniques, it is evident that micro/nano encapsulation and shape stabilization are found to be more effective in the aspects of thermal performance as compared to the macro and impregnation techniques, due to their advantages like enhanced heat transfer, no leakage, and corrosive resistance. Further, In-situ-polymerization and emulsion polymerization are found to be the most widely employed encapsulation technique due to their improved encapsulation efficiency and simple synthesis processes. From the findings, it is identified that PCMs with phase transition temperatures close to the ambient can have a great promise for improving the building's thermal comfort. This study may be helpful for the selection of PCMs and different encapsulation synthesis processes for building applications. Finally, certain challenges and recommendations for future researchers are also presented, which will result in advancement in the field of energy-efficient buildings.