We investigated the integration of form-stable paraffin/nanosilica composites into vacuum insulation panels (VIPs) to improve the thermal mass. In total, six form-stable paraffin/nanosilica composites were produced by absorbing paraffin in different types of nanosilica with different surface characters, hydrophobic and hydrophilic. In view of cost, a phase change material (PCM) composite prepared by hydrophilic precipitated silica was chosen to produce the PCM-integrated VIPs. The microstructure and phase change behaviour of the PCM composites were investigated. The thermal mass of the PCM-integrated VIPs was found to be improved. With integration of PCM the thermal conductivity of the VIPs was increased, although it was still very low compared to normal foam insulations. (C) 2015 Elsevier Ltd. All rights reserved.