The construction sector is one of the world’s largest greenhouse gas emitters, accounting for around 37% of CO2 emissions.1 The demand for low-carbon materials is increasing rapidly with increasing urbanization. Conventional bricks and cement, although durable, are energy-intensive to produce and add to the embodied carbon footprint of buildings.
Image Credit: Irene Miller/Shutterstock.com
A Sheffield-based company, earth4Earth, is piloting an alternative: fully recyclable ecobricks that avoid emissions during manufacture and actively capture and store carbon dioxide. If scaled, this technology could help transform construction from a major emitter into a net-zero enabler.
earth4Earth and the Ecobrick Concept
Founded in the UK, earth4Earth has developed a proprietary e4E binder, designed to cure at room temperature and enable the carbonation of excavated soil into structural bricks.2 Unlike cement or lime kilns, which rely on high-temperature calcination, this process eliminates most direct emissions from binder production.
The approach uses accelerated carbonation curing, with atmospheric carbon dioxide (CO2) that reacts with minerals in the binder, converting it into stable carbonates locked within the material. Over its life cycle, the brick functions as a carbon sink rather than a source.3
Ecobrick Variants and Specifications
earth4Earth currently produces several ecobrick variants, distinguished by the binder composition and carbon storage capacity.
Table 1. Data from earth4Earth.2
|
Code
|
e4E binder content
|
Binder type
|
Carbon uptake behavior
|
Notes
|
|
N10
|
10 %
|
e4E (room-temperature binder)
|
Absorbs CO2; lower uptake than N20/N30
|
Reusable; soil-return possible. Entry-level product
|
|
N20
|
20 %
|
e4E
|
Higher CO2 absorption
|
Reusable; soil-return possible. Balance of strength and sequestration
|
|
N30
|
30 %
|
e4E
|
Highest CO2 absorption in N-series
|
Reusable; soil-return possible. Maximum binder content
|
|
L10
|
—
|
Conventional lime
|
Captures CO2 but uses fired lime
|
Reusable; soil-return possible. Transition option
|
|
L0
|
0 %
|
No binder (earth-based)
|
No carbon-capture binder
|
Reusable; soil-return possible. Traditional earth brick
|
Pilot projects using these variants are already underway in the UK, where small-scale builds demonstrate their feasibility.4
Potential Contribution to Net-Zero
The potential of ecobricks lies in their ability to simultaneously address several key drivers of construction-sector emissions. By avoiding high-temperature lime and cement production, their manufacture significantly reduces embodied carbon from the outset.2 The carbonation curing process further enhances this advantage, permanently mineralizing CO2 into carbonates while simultaneously improving the strength characteristics of the bricks.3
Another critical factor is the utilization of waste streams. The bricks are made primarily from excavated soil that would otherwise go to landfill, reducing the need for virgin raw materials. At the end of their service life, the bricks can be crushed and remanufactured into new units, with the captured carbon remaining locked within the material. This circular pathway ensures that benefits extend beyond initial production, embedding recyclability into the entire lifecycle.
If independently verified and certified, ecobricks could be scaled for use in housing, commercial buildings, and infrastructure projects. This would support developers in meeting net-zero construction goals and align with broader carbon-reduction targets. Research indicates that carbonation-based building materials could collectively store more than 16 billion tons of CO2 per year if adopted at scale.5 This highlights the potential role of ecobricks within wider decarbonization efforts.
Carbon-Capture Brick Demonstration
Image Credit: earth4Earth/YouTube.com
Challenges to Overcome
Ecobricks face several hurdles before they can move from pilot use to wider adoption. Structural integrity is central: the bricks must comply with building codes and secure independent certification to UK and international standards.4
Field trials must also prove durability, particularly under freeze–thaw cycles, water exposure, and long-term weathering. Research on carbonation-based binders shows that results can vary with curing conditions and material composition, underlining the need for validation.6
Scaling production brings further risks. Larger volumes must not increase energy use or transport emissions, otherwise the climate benefits may be reduced. Cost will also be a decisive factor, as pricing must remain comparable to conventional bricks; commercial prices have not yet been disclosed at this stage. Finally, independent lifecycle assessments are required to verify carbon sequestration claims and ensure they are credible. Without this, market confidence could be limited.
The Future of Ecobricks
earth4Earth’s immediate priorities are certification for structural use and the development of production capacity. These steps will need to be managed carefully to preserve environmental gains. Collaboration with developers and architects working toward net-zero goals may support broader adoption. Early engagement with regulators, insurers, and procurement agencies could also help smooth the path to market acceptance.
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If technical, economic, and regulatory hurdles are addressed, ecobricks could provide a practical option for reducing emissions in mainstream construction. Their success would depend on performance and cost, but also on integration into supply chains and construction practices already in place. With clear evidence and verified results, they may become part of a broader toolkit of low-carbon materials that support long-term climate targets.
References and Further Reading
- Global Alliance for Buildings and Construction (GlobalABC), United Nations Environment Programme (UNEP). (2023). Global status report for buildings and construction: Beyond foundations. https://globalabc.org/resources/publications/global-status-report-buildings-and-construction-beyond-foundations
- earth4Earth. (2025). Our products – Carbon capture bricks (N10/N20/N30; L10; L0). https://earth4earth.co.uk/products
- Padmalal, A., Kulkarni, K. S., Rawat, P., & Sugandhini, H. K. (2024). Efficacy of accelerated carbonation curing and its influence on the strength development of concrete. Buildings, 14(8), 2573. https://doi.org/10.3390/buildings14082573
- BBC News. (2025). Sheffield company launches eco-bricks that ‘absorb carbon’. https://www.bbc.co.uk/news/articles/c8739gvn7gzo
- Van Roijen, E., Miller, S. A., & Davis, S. J. (2025). Building materials could store more than 16 billion tonnes of CO2 annually. Science, 387(6730), 176–182. https://doi.org/10.1126/science.adq8594
- RILEM TC 281-CCC. (2021). Understanding the carbonation of concrete with supplementary cementitious materials: A critical review. Materials and Structures, 54, 136. https://doi.org/10.1617/s11527-020-01558-w
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