Thermal energy storage systems have been recognized as one of the most efficient ways to enhance the
energy efficiency and sustainability, and have received a growing attention in recent years.Theuse of
phase change materials (PCMs) in building applications cannot only improve the in door thermal comfort
but also enhance the energy efficiency.The necessity to enhance thermal conductivity of the PCMs is
evident due to it slow energy charging/discharging rates.Therefore, the high thermal conductivity
additives or inserts to enhance thermal conductivity or to form the composite PCM are sought to achieve
high energy charging/discharging rates. In this paper,the experimental and the or etical methods to
enhance the thermal conductivity of the PCMs are summarized, and the thermal conductivity inserts/
additives in recent investigations are listed and summarized.The evaluation of each thermal conductivity
enhancement method is discussed