Innovative PCM-integrated calcium silicate panels for thermal regulation in building envelopes

• Calcium silicate boards host up to 72% by weight of Phase Change Material • PCM-impregnated panels show losses of less than 1%, ensuring leak-proof performance • Impregnation preserves the thermal storage capacity of PCM • PCM-impregnated panel effectively mitigate temperature fluctuation • Analyses show that the system is suitable for thermal buffering in buildings Buildings significantly contribute to global energy consumption and CO 2 emissions, underscoring the need for energy-efficient building solutions that enhance thermal comfort. Existing Phase Change Materials (PCMs)-based thermal storage solutions are promising but often suffer from leakage or loss of latent heat capacity. This study addresses these limitations by developing ready to use, leak-proof composite panels through direct impregnation of porous calcium silicate boards with organic PCMs for efficient latent heat storage in buildings. Two paraffinic PCMs were incorporated into two calcium silicate panels with different microstructure using the direct impregnation technique. The resulting composites boards were characterised by leakage tests, Fourier Transformed Infrared Spectroscopy, Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis, Scanning Electron Microscopy, thermal conductivity measurements, and controlled thermal response experiments. The panels achieved high PCM uptake exceeding 69 wt.% with negligible leakage (<1%), indicating excellent retention. DSC analysis revealed latent heats values ranging from 79 to 145 kJ/kg during melting and from 94 to 144 kJ/kg during solidification, confirming the significant thermal storage potential of the composites. Thermal stability comparable to pure PCMs was maintained below 156 °C, and performance remained durable after 200 heating–cooling cycles. Controlled thermal response tests showed effective temperature buffering, with gradual solidification process extending over approximately two days. The results highlight that porous calcium silicate panels are highly suitable host materials for direct PCM impregnation, enabling stable, scalable latent heat storage solutions for buildings, supporting their potential to improve energy efficiency and indoor comfort, marking significant progress in sustainable building material development.