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

Abstract

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'.

Keywords: circular economy; cob; earth construction; earthen architecture; rammed earth; soil.

Figure 1.

Left: the 'Orangerie' rammed earth building during its construction in the centre of Lyon (© Fabrice Fouillet). The arches are load-bearing structures holding up the timber floors and the flat roof. The timber floors ensure safety against earthquakes by tying the facades together and connecting them to the vertical timber structure around the lift (in the middle of the photograph). The partial on-site automation of the construction enabled the project to be delivered at a reasonable cost and in a reasonable time. Right: a single-family house in rammed earth, Burgundy, France (© Nicolas Meunier).

Figure 2.

Rate of growth for the last two decades of publications on dominant structures (concrete and steel) compared with publications related to earthen architecture found in Scopus©.

Figure 3.

The barriers for the use of earth as a construction material in the circular economy context; n stands for the number of occurrences reported by the interviewees, in the categories, subcategories or sub-subcategories. (Online version in colour.)