The Return of Rammed Earth: An Ancient Treasure for 21st-Century Sustainable Architecture

Building with earth is nothing new. As early as the late 18th century, Lyon-born architect François Cointeraux (1740–1830) championed the use of rammed earth. He published numerous treatises and founded “rural architecture schools,” convinced that earth was a material of the future, affordable, healthy, and durable. His vision, long forgotten, now resonates with today’s search for sustainable solutions in the face of climate change.

The Lyon region still bears witness to this tradition: hundreds of rammed-earth constructions, some several centuries old, are still standing. A heritage survey estimates that the metropolitan area has more than 700 buildings built with this technique. Proof that, despite its rustic appearance, compacted earth withstands the test of time.

The Thermal Properties of Rammed Earth: What Studies Reveal

Beyond this local example, scientific research confirms the thermal qualities of rammed earth.

A study conducted by Jiang et al. (2023) tested rammed-earth walls and demonstrated their excellent thermal and humidity regulation. The walls absorb moisture from the air and release it gradually, improving indoor comfort. Under experimental conditions, rammed-earth walls reduced indoor temperature fluctuations by several degrees compared to outdoor conditions, while stabilizing relative humidity. The authors concluded that earth-based construction helps reduce energy demand for heating and cooling.

Similarly, Ciancio et al. highlighted that rammed earth has a high thermal mass, capable of dampening temperature variations. This makes it particularly suitable for regions with strong day-to-night temperature swings. Their review also emphasized the material’s very low embodied energy: unlike concrete or steel, rammed earth requires no firing or heavy industrial processes, which significantly reduces its carbon footprint.

These findings align with observations in practice: L’Orangery in Lyon, for example, maintains indoor comfort without air conditioning, even during heatwaves.

L’Orangery in Lyon

The Confluence district in Lyon showcases the revival of rammed earth. In 2019, a 1,000 m², three-story office building, named L’Orangery, was inaugurated. The walls were built from raw earth blocks, extracted locally, compacted, and adjusted to millimeter precision.

The building stands out for its environmental performance. Constructed without packaging or waste, it requires no air conditioning in summer and only minimal heating in winter. Thanks to its thermal inertia, the capacity of earth to absorb and slowly release heat, the building can withstand heatwaves without heavy energy use.

In addition, the materials (earth and wood) were sourced exclusively from the Rhône-Alpes region, drastically cutting emissions linked to transport. L’Orangery has earned several prestigious labels (HQE, Effinergie+, BREEAM Excellence), recognizing its environmental performance.

According to the regional newspaper Le Progrès, the building “defies heatwaves” thanks to its earth walls, which keep indoor temperatures stable even during extreme heat.

Heritage and Local Adaptations

Rammed earth is not unique to Lyon. It can be found on several continents, adapted to local resources and traditions.

• Macao (China): A comparative study published in 2025 by Zhai et al. analyzed the composition and construction methods of traditional rammed-earth walls. The researchers found notable differences between sites: some walls use sandy soils, others clay-rich soils. This diversity reflects the adaptation of the material to local conditions. The study also highlights the architectural heritage value of these structures and stresses the importance of preserving them. These buildings demonstrate that rammed earth can adapt to a subtropical humid climate while maintaining durability.

• Croatia: In eastern Croatia, Brkanić Mihić et al. (2024) examined traditional rammed-earth houses. Soil analyses showed varying proportions of sand, silt, and clay, which directly influence strength and durability. The study emphasizes that rammed earth allows the use of abundant local resources, but also raises questions about seismic stability. This underlines that while earth offers outstanding thermal and ecological performance, construction methods must be adapted to geographical and environmental constraints.

• Australia, Africa, the Americas: According to Niroumand et al. (2013), rammed earth is one of many earth-based construction techniques used worldwide, alongside adobe, cob, and wattle-and-daub. Their article points out that these methods are making a comeback today, as they significantly reduce construction-related emissions. Rammed earth, endlessly recyclable, embodies a model of circularity long before the concept became widespread.

Conclusion

From visionary François Cointeraux in the 18th century to modern experiments like L’Orangery in Lyon, and from research in Macao to case studies in Croatia, rammed earth shows remarkable continuity.

Recent scientific studies confirm its qualities: thermal and humidity regulation, high thermal mass, low environmental impact, and infinite recyclability. These results, reinforced by real-world examples, demonstrate that rammed earth is not a relic of the past but a material fully suited to contemporary challenges.

Of course, challenges remain: water resistance, compliance with seismic standards, and the transfer of know-how. Yet the current momentum shows that this material is reinventing itself as a credible answer to climate and energy challenges.

In a world where construction accounts for a major share of greenhouse gas emissions, rammed earth embodies a sober, local, and sustainable path. A millennia-old heritage, it is now emerging as a true treasure of the 21st century.

Sources

[1] TOPOPHILE, « Le pisé des villes : le patrimoine lyonnais ».

[2] CONSTRUCTION-PISE, « Lyon Confluence – L’Orangery ».

[3] CONSTRUCTION21, « L’Orangery, un bâtiment en terre crue au sein de Confluence ».

[4] LE PROGRÈS, (2023), « Ce bâtiment en terre crue défie la canicule », publié le 21 juin 2023.

[5] JIANG, Y., et al., (2023), « Thermal and Humidity Performance Test of Rammed Earth », PMC (PubMed Central).

[6] CIANCIO, D., (2015), « Rammed Earth: An Overview of a Sustainable Construction », University of Western Australia.

[7] ZHAI, J., et al., (2025), « Comparative Analysis of Physical Characteristics of Traditional Rammed Earth in Macau », Nature Scientific Reports.

[8] BRKANIĆ MIHIĆ, M., et al., (2024), « Architectural Features and Soil Properties of Traditional Rammed Earth Houses: Eastern Croatia », Buildings, MDPI.

[9] MARTIN-ANTUNES, M., et al., (2025), « Recent Developments in Stabilized Rammed Earth: Testing », ScienceDirect.

[10] NIROUMAND, H., et al., (2013), « Various Types of Earth Buildings », ScienceDirect.