In this paper, a novel technology to improve the thermal performance of reefer container envelopes using a Phase Change Material (PCM) has been investigated. To that end, an external PCM layer was integrated with an insulated sandwich panel, in order to reduce and displace the heat flux phase caused by the external climatic conditions. The proposed technology was evaluated using an experimental and numerical design study. Specifically, during the experimental activities, a prototype panel was first tested inside a climatic test room and subsequently assembled on mini cold rooms and evaluated under real summer environmental conditions in Ancona (Italy). Finally, the numerical analysis was carried out using Finite Element Method (FEM) software in order to simulate a two-dimensional unsteady-state heat transfer with PCM. The calculation results were compared with the experimental values in order to validate the mathematical model, achieving a high reliability (correlation coefficient equal to 0.95). (C) 2016 Elsevier Ltd. All rights reserved.