The present invention discloses a heat barrier article for mounting on an exterior wall of a building and a method thereof. The heat barrier article comprises a phase change material, PCM, a high density polyethylene housing member, an insulator layer and a metallic layer. The PCM comprises a eutectic mixture having one or more melting points configured for absorbing and releasing heat from and to outdoor ambient, comprising 96.0 - 98.0% calcium chloride hexahydrate (CaCl2·6H2O), 1.0 - 1.5% strontium chloride hexahydrate (SrCl2·6H2O), 0.2 - 1.0% sodium chloride (NaCl) and 0.2 - 2.0% potassium chloride (KCl).