Green facade systems (GFS) are a growingly popular resource in climate adaptation. However, current GFS are characterized mainly by high costs, high embodied carbon and short life span materials. This study presents the early-stage design of a cost-effective and low-embodied carbon GFS prototype. This prototype was developed and tested with a research through design (RTD) methodology. The first RTD iteration dealt with cost-effectiveness and low-embodied carbon and categorized the prototypes into three main GFS design typologies: facade-based typology, balcony forest typology, and the redesign of a GFS patented facade-based product. In iteration 2, the designs produced in iteration 1 were evaluated through a life cycle and cost analysis of the three typologies and the existing designs were refined. Finally, in iteration 3, the hydrological and structural performance was tested as a 3D printed GFS mock-up. This process resulted in a modular, cost-effective and low-embodied carbon early-stage GFS prototype. It was found that the selected materials (recycled), plants, substrate (with high-water holding capacity), GFS typology (façade-based with a light structure) and its fixing system (modular) lowered the costs and the embodied carbon of the GFS prototype by comparison to other GFS products.