According to an investigation performed by the European Union residential and commercial buildings are responsible for about 40 % of the total energy consumption and CO2 emissions in Europe and up to 75 % of the building stock needs a sustainable renovation over the next 40 years. As a result, energy performance has become an important issue in the renovation of existing buildings and this paper present the development and optimization of a new type of external wall insulation, which will be highly suitable as one of the technical solution needed in a sustainable renovation. The external wall insulation system consists of a thin and light plate of High Performance Concrete connected with an insulation block. The panels have been the subject of different optimizations, such as an optimization of the insulation type and the design in order to minimize the thermal bridge effect and an investigation of the hygrothermal performance of the panels. The result are a new system of re-insulating panels which because of optimizations and the use of the High Performance Concrete plate will ensure a long life time of the system, an outstanding thermal performance, low CO2 emission, a low consumption of raw material and an attractive surface with minimum maintenance.