Repurposed coconut oil waste as a viable phase-change material for thermal energy storage applications

Phase-change materials (PCMs) are widely used to enhance thermal energy storage in building envelopes; however, their large-scale adoption remains constrained by the cost, availability, and environmental footprint of conventional paraffin-based materials. This study investigates wasted coconut oil (WCO) as a circular, waste-derived PCM by evaluating its thermophysical properties and thermal storage performance. Differential Scanning Calorimetry (DSC) was employed to characterize phase transition behavior, and experimental testing of PCM-integrated concrete panels was conducted to validate a numerical model for extension to building-scale applications. Results show that WCO exhibits phase-change characteristics comparable to virgin coconut oil and remains thermally functional even at high levels of contamination. While its thermal behavior aligns with that of conventional organic PCMs, its key advantage lies in enabling comparable performance at significantly lower cost and environmental impact. Although latent heat decreases with increasing impurity content, performance losses can be mitigated through volumetric compensation, enabling effective diversion of larger quantities of waste material. By transforming a readily available waste stream into a functional thermal storage medium, WCO provides a pathway for both improving the economic feasibility of PCM deployment and diverting waste from landfills. Overall, the findings position WCO as a viable circular PCM, offering a scalable pathway for integrating waste-derived materials into energy-efficient building systems.