The objective of this study is to investigate the effect of supercooling repression on the TMA clathrate by adding ethylene glycol. For this purpose, phase change temperature, supercooling, specific heat, latent heat and rate of volume change were measured and evaluated experimentally for heat source temperatures of -6$^{circ}C$, -7$^{circ}C$, -8$^{circ}C$. The results show that supercooling was decreased. Thus the experimental results are expected to be used for the increase of coefficient of performance of low temperature thermal storage system in the building.