This article aims to evaluate the potential application of prefabricated panels in energy retrofit of facades in the Portuguese building stock. The fundamentals of this study were part of Annex 50. which was an international ECBCS IEA project. with the purpose of developing an innovative concept of building renovation for the most representative buildings based on prefabricated systems. https://www.roneverhart.com/Modern-Rectangular-Keyed-Entry-Pocket-Door-Emtek-2113/