The building envelope (roof, façade and basements) is the key element to address in order to achieve the energy efficiency in the retrofitting of buildings, where the façade represent the largest part of the heat transmission surface and includes a number of critical components (like windows, balconies, ventilation units,etc) and thermal bridge phenomena.The present project aims to develop an energy efficient integrated system composed by an innovative concept, built on composite materials, and advanced multifunctional panels with technological modules integrated in the façade for building envelope retrofitting. The following solutions will be developed:- Innovative façade concept for retrofitting based on new industrialized constructive system integrating advanced multifunctional panels, technological modules and installations; allowing personalized configurations for each façade typology, orientation and local climate conditions, always using standardized panels and technological modules. It will be cost effective in service life, with low maintenance, easy assembly and disassembly.- Energy Efficient panels and modules integrated in the façade will include a particular technology for reducing energy demand of the building or for supplying energy by means of RES; two new energy efficient modules will be developed: Advanced Passive Solar Protector and Energy Absorption auto mobile unit, Advanced Passive Solar Collector and Ventilation Module.- A set of flexible, lightweight and cost-effective structural panels, easy to be industrialized and assembled, made of composite materials (FRP - Fibre Reinforced Polymer).The solution will be demonstrated in a real building in Spain, in a region with a continental climate, where extreme conditions in summer up to (>35°C) and in winter (<0°C), covering the different seasons. The building will be monitored before and after the retrofitting with the new Retrofitting system to evaluate the performance solutions.