Clay celebrates its comeback
Earth is moving to the centre of research and building practice as a climate-friendly alternative to energy- and emission-intensive concrete. The Innosuisse project "Think Earth" brings together researchers, architectural firms and the construction industry with the aim of establishing locally available, recyclable and technically advanced earthen and hybrid constructions as new standards. Behind this is the clear vision of a circular economy and climate-neutral construction as a real alternative to the current construction method.
Clay has been tried and tested for thousands of years, consists of local clay, silt and sand, can be used without energy-intensive firing processes and is available in almost unlimited quantities. In contrast to concrete, the production of which causes considerable CO₂ emissions by burning limestone, loam scores points with its minimal energy consumption during extraction and processing. According to estimates from various sources, the production of concrete generates an average of 800-900 kg of CO₂ per tonne, whereas clay often only produces a tenth of this and usually none at all, provided it is dried naturally
The clay pavilion in Horw
As part of the “Think Earth” programme, ETH Zurich, HSLU and industrial companies are working together to bring clay and wood into innovative applications as a material base. One milestone is the clay pavilion in Horw, where clay and wood elements are combined in hybrid form with recycled Oulesse, a mixed demolition material developed by Oxara. The prototypes are created in close collaboration with the construction industry and students. The aim is to create modular, prefabricated clay building components with reliable strength, versatile and deconstructable, for multi-storey residential construction and flexible architecture
Advantages, challenges and recycling potential
Earth is not only energy-saving, but can also store CO₂, especially when organic additives are added – it can even have a climate-positive effect. Earth building materials can be easily separated and reused when buildings are dismantled. The recycling process is not costly and enables a genuine circular economy.
Clay is already available in abundance regionally as excavated clay or as a by-product (“filter cake”) from gravel and excavation washing. So far, widespread use has failed mainly due to a lack of standardisation and market maturity. The “Think Earth” project partners are now working intensively on this
Clay construction hybrid solutions are still more cost-intensive than conventional concrete construction, but advances in industrial production, material mixing and quality assurance are increasingly bringing them within reach for the masses
From niche to standard?
Researchers at HSLU and ETH Zurich are working on the standardisation of the new hybrid earth building elements, so that market entry in the next ten years is realistic. The industry is showing great interest. Especially because “waste” from excavations is becoming a key raw material. With clay, wood and intelligent hybrid technologies, a building principle is available that conserves natural resources, offers climate benefits and still enables architectural diversity. Clay is experiencing an innovation and image revival. “Think Earth” and the earth pavilion show how research and the construction industry are working together to deliver solutions for the building revolution. A small ecological footprint, circular potential and healthy living are more than just a trend – they mark the path to urban building culture in the 21st century.