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

Approximately 80% of the buildings that will exist in 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. The Reeco-Soil approach addresses this gap, with the potential to transform existing buildings from static, resource-consuming assets into dynamic, living systems that actively regenerate the ecological and human environments they inhabit.