As the global carbon neutrality goal enters a new stage, the construction industry is at the forefront of emission reduction and transformation. The transition from “consumer” to “carbon sink carrier” has become a new proposition for the construction industry to break through bottlenecks. In this opportunity, biochar has come into view with its dual properties of “multifunctional building materials + carbon sequestration”. Read on to learn how biochar provides a feasible idea for the industry to move towards a low-carbon future.
Decarbonization Background in Construction Industry
Emissions Continue to Rise
Construction industry, including both building operations and material production, accounts for approximately 34% of global CO₂ emissions. Notably, cement production alone contributes around 8%. According to IEA, global energy-related CO₂ emissions continued to rise in 2023, reaching 37.4 billion tonnes. Under carbon neutrality goals, construction has become a critical sector that must be addressed urgently.
Policy Focus Intensifies
In 2024, the European Union released the Carbon Removal and Carbon Farming Regulation. For the first time, “biochar storage in buildings” was included in the scope of certification methodology. Meanwhile, green building certification systems in various countries—such as BREEAM and LEED have strengthened incentives or recognition pathways for low-carbon materials like biochar.
Applications and Advantages of Biochar in Construction
Biochar offers a range of engineering performance benefits.Therefore, it is becoming an important component of green building materials. Its application not only improves the durability and comfort of buildings. Similarly, it helps achieve energy conservation, emission reduction, and green and low-carbon building goals in many links.
Construction Material Additive
- Strength Enhancement: Incorporating 1–2 wt% biochar into concrete can improve flexural strength by approximately 15%. Additionally, substituting around 1% of fine aggregates with biochar can increase compressive strength by about 10%.
- Lightweight Material: When processed into lightweight aggregate, biochar can reduce the self-weight of concrete by 10–20%, thereby cutting emissions associated with material transportation.
Eco-Composite Materials
- Thermal Insulation: Biochar–clay composites can achieve a thermal conductivity as low as 0.101 W/m·K, providing excellent insulation.
- Sound Absorption: Biochar panels made with larger particle sizes can reach a sound absorption coefficient of 0.33 at 2000 Hz, offering effective noise reduction.
- Moisture and Mold Resistance: In real-building tests, insulation layers incorporating biochar helped maintain indoor humidity between 40–60% with no mold formation.
Carbon Sequestration Mechanism of Biochar in Construction
In construction materials, biochar serves as an effective medium for long-term carbon sequestration. Its inherently stable structure and strong synergy with cementitious systems allow carbon to remain in solid form for centuries. The carbon retention mechanism can be summarized as a “three-lock” system:
1. Chemical Lock
Stable Aromatic Carbon Structure
In biochar machine, biomass undergoes pyrolysis under high temperature and low-oxygen conditions. This thermal decomposition process forms polyaromatic carbon clusters in biochar. When the hydrogen-to-carbon ratio (H/C) is below 0.4, the biochar becomes highly resistant to microbial or oxidative degradation.
2. Physical Lock
Hydration Products Encapsulation
Once mixed into cement paste, porous biochar absorbs water, which enhances hydration of C₃S/C₂S. Meanwhile, its surface functional groups, such as carboxyl/hydroxyl groups, act as nucleation sites for C‑S‑H gel. Thus, it forms continuous encapsulating layer blocks oxygen & water intrusion.
3. Mineral Lock
Carbonate Deposition Promotion
The porous structure of biochar facilitates CO₂ diffusion and moisture retention. It accelerates the carbonation reaction: Ca(OH)₂ → CaCO₃. Moreover if the biochar is rich in Si, Mg, or Ca, it can further induce the formation of magnesium carbonates, enhancing long-term mineral-based carbon sequestration.
Biochar: Building Toward a Low-Carbon Future
With both material and climate benefits, biochar offers a practical path for decarbonizing construction. Its integration helps turn buildings into long-term carbon sinks—paving the way for greener, more resilient cities. If you are looking for solutions for producing building material grade biochar, feel free to contact us.
