Earth as construction material in the circular economy context: practitioner perspectives on barriers to overcome.

The need for a vast quantity of new buildings to address the increase in population and living standards is opposed to the need for tackling global warming and the decline in biodiversity. To overcome this twofold challenge, there is a need to move towards a more circular economy by widely using a combination of alternative low-carbon construction materials, alternative technologies and practices. Soils or earth were widely used by builders before World War II, as a primary resource to manufacture materials and structures of vernacular architecture. Centuries of empirical practices have led to a variety of techniques to implement earth, known as rammed earth, cob and adobe masonry among others. Earth refers to local soil with a variable composition but at least containing a small percentage of clay that would simply solidify by drying without any baking. This paper discusses why and how earth naturally embeds high-tech properties for sustainable construction. Then the potential of earth to contribute to addressing the global challenge of modern architecture and the need to re-think building practices is also explored. The current obstacles against the development of earthen architecture are examined through a survey of current earth building practitioners in Western Europe. A literature review revealed that, surprisingly, only technical barriers are being addressed by the scientific community; two-thirds of the actual barriers identified by the interviewees are not within the technical field and are almost entirely neglected in the scientific literature, which may explain why earthen architecture is still a niche market despite embodying all the attributes of the best construction material to tackle the current climate and economic crisis. This article is part of the theme issue 'The role of soils in delivering Nature's Contributions to People'.

Components reuse in the building sector - A systematic review.

Widespread reuse of building components can promote the circularity of materials in the building sector. However, the reuse of building components is not yet a mainstream practise. Although there have been several studies on the factors affecting the reuse of building components, there is no single study that has tried to harmonize the circumstances affecting this intervention. Through a systematic literature review targeting peer-reviewed journal articles, this study intends to identify and stratify factors affecting the reuse of components of the superstructure of a building and eventually delineate correlations between these factors. Factors identified throughout this study are classified into six major categories and 23 sub-categories. Then the inter-dependencies between the barriers are studied by developing the correlation indices between the sub-categories. Results indicate that addressing the economic, social and regulatory barriers should be prioritized. Although the impact of barriers under perception, risk, compliance and market sub-categories are very pronounced, the highest inter-dependency among the sub-categories is found between perception and risk. It suggests that the perception of the stakeholders about building components reuse is affected by the potential risks associated with this intervention.