Imagine you are standing in front of a multimillion-pound building in the centre of the French city, Lyon. It radiates warmth and history with its rammed earth structural walls. Two hundred miles away, a small house in the Beaucastel winery, Provence, shares a similar texture and aesthetic.
The soil used for both buildings was excavated earth that had been considered waste, leftover from the construction site or excavated from the nearby area. It was destined for landfills.
Once mixed with water and compacted, it creates a material strong enough to build walls. But watch out for counterfeits. It should not be confused with cement-stabilised rammed-earth that requires a huge quantity of cement due to the necessary thickness of the walls.
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Cement production alone contributes to three per cent of global greenhouse gas emissions. Now, the construction sector needs to transition towards a more sustainable model by maximising the use of materials at their highest value and eliminating waste.
Building with rammed earth could be scalable. But despite their recyclability, energy efficiency, low-carbon nature and centuries-long history of successful applications, earthen buildings are still underrepresented in the green building movement and is poorly regarded by architects, property developers and local authorities.
Most studies of earthen construction address the technical challenges, such as strength of walls, water damage and energy performance. But my research shows that the future of earth as a construction material faces challenges that go beyond mere technical issues. So why has this ancient, ecological approach not become a cornerstone of modern green architecture?
Some people still consider earth to be “the poor man’s stuff”, associated with poor technical characteristics, like weaker or less resilient walls.
Earthen architecture is either seen as a relic of the past or exclusive to luxury environmentalists, according to research. These socio-cultural perceptions create a stigma that limits its acceptance in modern construction practices.
It’s time to break down those outdated perceptions to recognise earth as a valid and sustainable construction material. Once reframed as an opportunity, earth can become the cornerstone of future sustainable cities, provided it is not stabilised with harmful components, such as cement.
The soil used for construction is not the fertile topsoil for agriculture, but the subsoil excavated during foundations or from infrastructure works. It does not contribute to desertification and does not decline the soil health.
Rebuilding trust in earthen materials
The way we approach construction must also shift. Earthen materials do not perform like concrete. There are questions about their resistance to extreme weather. However, when properly designed and implemented, earthen buildings can last for decades, even centuries.
Earthen materials differ tremendously (it’s soil, after all) so some can be more susceptible to water damage than others. That makes standardisation tricky. But with an appropriate design, earthen buildings can have extraordinary longevity.
Earth construction is a labour-intensive process, without the scope for much automation, so it often comes with higher initial manufacture costs. In the absence of a well-established supply chain for earthen materials, builders have to source and test materials on a project-by-project basis, increasing costs.
Without taxes on carbon-intensive raw materials and with high taxes on labour in Europe, earthen construction is often considered economically unattractive to developers. Governments can unlock the potential of earthen architecture by providing financial incentives or subsidies that make certification and insurance easier and cheaper. Accessible certifications and specific regulations for the use of earth as a construction material are highly demanded by practitioners.
Scaling up sustainable and recyclable earth construction hinges on the disruption of traditional design and building industry supply chains. That begins with involving masons and artisans in design decisions, to ensure that plans are adapted to accommodate earth materials.
Building with earth is more than possible. It is practical, sustainable and necessary for a greener future. But to transform the sustainability of the construction sector, we need to break through walls.
Rabia Charef, Senior Research Associate in Circular Economy & Digitalisation, Lancaster University
This article is republished from The Conversation under a Creative Commons license. Read the original article published Dec. 16, 20924.
