Bio-based PCMs are made from underused feedstock, such as soybean oil, and are significantly less flammable than paraffins. In this study, Bio-based PCMs were prepared with silica fume through a vacuum impregnation process. Silica fume is a mineral admixture product with an impermeable pore structure, and it is one of the most feasible candidates for use as economical, light-weight thermal energy storage materials for buildings [15,16]. We also used exfoliated graphite nanoplatelets (xGnP) to improve the thermal conductivity because PCMs have a low thermal conductivity. The vacuum impregnation process that was used in this study guarantees that the Bio-based PCM composites can store heat after incorporation. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), Differential scanning calorimetry (DSC), Thermo gravimetric analyses (TGA), and TCi analysis were then carried out to determine the characteristics of the Bio-based PCM and Bio-based PCM composites. (C) 2015 Elsevier B.V. All rights reserved.