In the context of strategies for mitigating the impacts of climate change within European cities, increasing attention is being paid worldwide to the use of urban green infrastructure which, in addition to the potential for improving the quality of the urban environment, allow significant amounts of CO2 to be removed from the air. However, considering the peculiarities of the dense European cities, most of the available surfaces in urban areas are the perimeter walls of buildings of considerable age that are in urgent need of measures to upgrade their energy performance. Based on this premise, this paper investigates the potential for CO2 storage resulting from the application of energy retrofit solutions using biogenic insulating materials. Starting from the analysis of the demand for insulation materials necessary for the energy requalification of the residential existing building stock in 28 European countries, following the renovation target fixed by EU, the research analyses, through the adoption of a dynamic LCA approach, the environmental benefits of bio-based materials compared to traditional solutions. The use of these materials, especially if they are fast-growing - as the study shows - offers several advantages in terms of climate change mitigation by reducing the energy needs and CO2 emissions of the existing building stock and increasing carbon storage capacity within cities. The results of this study are intended to provide a robust database on which to build a model of circular building renovation that takes into account the environmental long-term effects of measures for increasing energy efficiency of buildings.