Ecologically Active Soils for Regenerative Retrofitting of Existing Buildings: A Systematic Review

Approximately 80% of the buildings that will exist in Global North countries by 2050 have already been built, yet most perform poorly in terms of energy efficiency and fail to deliver net-positive outcomes. Ecologically active soils, which are engineered to provide the moisture, porosity, and nutrient conditions necessary for plant growth, offer a promising yet underexplored pathway for the regenerative retrofitting of existing building envelopes. This paper presents the rationale, objectives, and results of the Regenerative Retrofitting Via Ecologically Active Soil Structures (Reeco-Soil) project, which investigates the state of the art of ecologically active soil-based building retrofitting through a Systematic Literature Review (SLR) conducted in accordance with PRISMA 2020 guidelines, drawing on searches of the Scopus and Web of Science databases. Results confirm that bio-based clay composites can achieve significant reductions in thermal conductivity, and that robotic and spray-based fabrication methods are capable of depositing earthen materials onto complex building geometries. However, peer-reviewed evidence directly addressing biological component integration remains critically scarce. As conclusion, the review reveals substantial opportunities for integrating earthen materials, biological components, and digital fabrication technologies into regenerative retrofitting strategies, while also highlighting research gaps that must be addressed before they can be implemented at scale.