How does rammed earth board compare in life cycle assessment?

As the construction industry searches for ways to cut carbon, the rammed earth board has moved from a niche technique to a serious contender in sustainable building. But how does it actually perform when measured across a full life cycle assessment (LCA)? The answer is more nuanced than a simple "green material" label, and understanding the comparison helps architects, contractors and developers make informed choices.

A life cycle assessment tracks a material from raw material extraction, through manufacturing and transport, to installation, use and eventual disposal or recycling. For cladding and wall boards, the two phases that matter most are the embodied impacts of production and the operational energy they save or demand over the building's life. When rammed earth board is placed against conventional options such as concrete, fired brick and natural stone, the differences show up clearly in both phases.

The embodied energy advantage of rammed earth board

The biggest advantage of rammed earth board in an LCA is embodied energy. Traditional rammed earth is made by compacting locally sourced soil with a small amount of water and, in some cases, a stabiliser. Because the material is not fired in a kiln and does not require the energy-intensive clinker production of cement, its production footprint is far lower than that of fired brick or concrete. Research comparing residential structures has found that the embodied carbon of a brick-and-concrete house can be roughly 70 percent higher than that of a comparable modern rammed earth house, a gap driven almost entirely by the manufacturing stage.

It is worth noting that the choice of stabiliser matters. Unstabilised earth offers the lowest embodied impact, while cement stabilisation can raise the embodied carbon of the wall significantly. This is precisely why modern flexible rammed earth boards, produced as modified clay materials, are engineered to deliver the visual and tactile character of rammed earth without relying on heavy cement content, keeping the production-stage footprint low.

Rammed earth board versus concrete and fired brick

Concrete and fired brick dominate modern construction, but both carry heavy production burdens. Cement manufacturing alone is responsible for a significant share of global industrial CO2 emissions, and firing clay brick requires sustained high temperatures. When these materials are compared with rammed earth board across a cradle-to-gate assessment, the earth-based option consistently shows lower carbon footprint, lower water footprint and lower embodied energy per square metre of wall.

There is also a structural advantage that feeds into the LCA. A flexible rammed earth board is thin and lightweight, which reduces the load on the building frame and allows smaller foundations. Lighter panels also mean more product can be shipped per container, cutting transport emissions per square metre of installed surface. For projects that import cladding, this logistics saving is a real and measurable part of the life cycle picture.

Operational performance and thermal mass

A life cycle assessment does not stop at production. The way a material behaves in use can offset its embodied impact over decades. Earth-based walls are known for high thermal mass, which moderates indoor temperature swings and reduces the energy needed for heating and cooling in many climates. This operational saving is often overlooked in simplified comparisons, yet it can tip the balance decisively in favour of earth-based cladding over thin, low-mass alternatives.

For exterior applications, rammed earth board also offers a durable, low-maintenance surface that weathers gracefully, avoiding the frequent recoating or replacement cycles that add hidden impacts over a building's life. Fewer replacements mean fewer material inputs, less waste and lower cumulative emissions, all of which improve the long-term LCA result.

Where rammed earth board needs careful consideration

No material wins every category, and an honest LCA comparison should acknowledge the trade-offs. Transport distance matters: earth-based boards sourced from a distant factory lose some of their advantage over locally produced concrete products. The stabiliser content, as noted, can raise embodied carbon if overused. And in very humid or exposed environments, the detailing and protective treatment of earth-based cladding must be specified correctly to ensure long service life.

These factors are manageable, but they explain why the best LCA results come from choosing a well-engineered product, specifying it correctly, and keeping transport distances short. A modern flexible rammed earth board, produced under controlled factory conditions, addresses many of the variability issues that plagued traditional on-site rammed earth while retaining its environmental strengths.

The verdict: a strong performer in green building

When the full life cycle is considered, rammed earth board compares favourably with concrete, fired brick and natural stone in the categories that matter most to sustainability: embodied carbon, embodied energy, water footprint and operational performance. Its main weaknesses, transport distance and stabiliser content, are controllable through good specification and sourcing.

For architects and developers committed to green building materials, the flexible rammed earth board offers a practical way to bring the look and environmental performance of rammed earth to modern facades and interiors, without the weight, cost and site complexity of traditional construction. With options ranging from natural earth tones to rammed earth board gradient finishes, it is a material that performs as well on paper as it does on the wall.