The ongoing climate change, resulting from increasing levels of environmental pollution, requires tangible actions aimed at the pursuit of truly sustainable global development, as indicated by the 17 Goals of the UN 2030 Agenda. Among human activities, the construction sector, notoriously a consumer of energy and raw materials, as well as a producer of waste and climate-changing gases, requires special attention from all stakeholders. One of the possible strategies to increase the sustainability of urban systems, restore degraded ecosystems and mitigate the effects of climate change is the adoption of Nature Based Solutions, including Green Roofs and Vertical Greenery Systems. In particular, in high-density urban areas, vertical greening strategies are emerging as a possible solution to address the shortage of green spaces, not requiring the occupation of land. Unlike what happens with new buildings, in which Vertical Greenery Systems are integrated into the building envelope already at the design stage, their application in the redevelopment of existing buildings is not an immediate solution, as it must be confronted with the morphological, volumetric, technological and material characteristics of the buildings to be renovated. The paper presents the progress of a research project that, through the design of a modular construction system, adaptable to the different characteristics of existing buildings, aims to allow the easy application of Vertical Greenery Systems in buildings constructed since the 1950s, which are most in need of energy and architectural retrofit.