Bio-Based Composites in Building: A Concrete Move to Reduce Emissions, Costs, and Dependence on Fossil Resources

Bio-based materials, particularly composites, are gaining visibility in the sustainable construction sector. This shift is not only driven by a desire for innovation or aesthetics but also by their ability to meet tangible environmental, economic, and technical requirements.

Bio-based composites are distinguished by their hybrid composition: a matrix, often plant-based, and a reinforcement made of natural fibers. Their appeal lies in the measurable reduction of carbon footprint, their adaptability to local resources, and their contribution to reducing operational costs related to energy consumption and maintenance.

Reducing Carbon Emissions

Bio-based composites directly reduce greenhouse gas emissions in several ways:

• Production: Their production consumes less energy compared to conventional materials such as cement or synthetic resins. For example, the production of hempcrete can reduce CO₂ emissions by up to 60% compared to traditional concrete due to much lower energy consumption.

  
  

• Plant Origin: The plants used as fibers (hemp, flax, cellulose) store carbon during their growth, offsetting some emissions throughout their lifecycle. On average, one hectare of hemp can capture up to 15 tons of CO₂ per year, which helps reduce the carbon footprint of buildings.

• Thermal Durability: Once integrated, these materials reduce the need for heating and cooling, thus decreasing energy consumption in buildings. For instance, a building with hemp insulation can reduce heating needs by 40 to 50%.

  
  

Case Study – WISE, Wales

The Wales Institute for Sustainable Education (WISE), in the UK, uses hempcrete in its walls. The building was designed with an eco-efficient construction approach. The hempcrete used in the exterior walls provides optimal thermal and acoustic insulation. Studies conducted over several years showed that the energy impact was reduced by 30 to 40% compared to traditional buildings of the same size, reducing heating consumption during the winter months. Additionally, the building was designed to minimize indoor humidity, thanks to the natural absorption of moisture by hempcrete. This phenomenon contributes to thermal stability and the creation of a comfortable indoor environment, while eliminating the need for expensive mechanical ventilation systems.

The real-time monitoring system installed on the site tracked data on energy efficiency, humidity, and temperature variations. The results confirmed an energy saving of 50% compared to a traditional building, with heating costs reduced by over £700 per year for a medium-sized building. These results demonstrate that bio-based materials, like hempcrete, can't only reduce a building's carbon footprint but also generate significant long-term savings.

https://cat.org.uk/info-resources/free-information-service/building/the-wise-building/

Costs: Reasoned Investment and Long-Term Savings

Although some bio-based materials have a higher initial cost compared to conventional solutions, they offer significant operational savings:

• Effective Insulation: Reducing thermal losses decreases energy needs and thus reduces operational costs. For example, a building with hempcrete insulation can save up to 20 to 30% on annual heating bills.

  
  

• Increased Longevity: Bio-based materials, when properly protected and maintained, show good resistance to thermal variations and humidity, reducing the need for renovation or replacement. A hempcrete house, for example, can last over 50 years without requiring major renovation work.

• Reduced Transportation: By sourcing raw materials locally, logistical costs are minimized, especially for projects in rural or decentralized areas. For example, a project using locally sourced bio-based materials can reduce transportation costs by up to 40% compared to conventional imported materials.

  
  

Case Study – Using Straw as Insulation in a House in Poland

An individual house built in northern Poland was insulated using prefabricated straw bales inserted into a wooden frame. This solution allowed the building to achieve an annual energy consumption of less than 60 kWh/m², suitable for cold climates.Life cycle analysis of the building showed a reduction of more than 40% in CO₂ emissions compared to an equivalent concrete building. This environmental gain is explained by the low embodied energy of straw, its local availability, and its ability to store carbon.

https://www.mdpi.com/2071-1050/14/24/16511

Availability and Valorization of Local Resources

One of the main advantages of bio-based composites is their ability to adapt to local supply chains. This promotes a regional circular economy and supports the emergence of decarbonized agricultural and industrial sectors.

• Available Materials: Hemp, flax, wood, bagasse, coffee grounds, straw, and even recycled textiles can be used to make composites. For example, a straw-based construction project can reduce costs by 30 to 40% compared to traditional materials.

  
  

• Rural Development: Some regions are developing cooperatives around industrial hemp, creating local added value. In France, cooperatives in the Hauts-de-France region have seen their hemp production increase by 25% annually for the past five years.

• Waste Reduction: Incorporating by-products (such as coffee grounds or recycled wood fibers) gives a second life to organic materials that were previously undervalued. In Spain, a study showed that integrating recycled wood fibers into composites can reduce production costs by 15% while improving durability.

Case Study – Improving Thermal Performance of Plaster with Coffee Grounds in Marrakech

A study conducted in Marrakech (Lachheb et al., 2019) evaluated the integration of used coffee grounds into plaster applied to a typical home in the region. The composite material, incorporating 6% coffee grounds by weight, improved the insulating properties of the plaster by reducing its ability to conduct heat. This improvement led to a 20% reduction in annual energy needs and a decrease in CO₂ emissions by 1,500 kg per year, simply by replacing conventional plaster with this bio-based solution. This case study illustrates how a locally available organic waste can be valorized in simple construction materials, with measurable benefits in terms of energy efficiency and environmental impact.

Technical Performance and User Comfort

Beyond their environmental impact, bio-based composites meet performance requirements:

• Effective Thermal and Acoustic Insulation: These materials limit heat transfer and noise disturbances. For example, hemp-based composites reduce exterior noise by 30% on average, improving interior acoustic comfort.

• Natural Hygrometric Regulation: They help maintain healthier indoor air quality without energy-intensive equipment. A hempcrete wall, for example, can absorb and release moisture naturally, maintaining a constant humidity level, which is ideal for health.

• Long-Term Stability: When properly protected from excessive moisture or UV rays, these materials remain stable over time. Hempcrete is particularly resistant to fungal attacks and mold, ensuring the durability of the building.

Conclusion

The use of bio-based composites is part of a broader approach to impact reduction, without compromising performance. Results observed on several projects show a significant reduction in CO₂ emissions, improved energy efficiency, and good potential for scalability at different levels.

However, their large-scale adoption depends on factors such as industrial availability, product standardization, feedback from construction sites, and professional support. For project owners and designers, these materials offer a tangible opportunity to transform practices by combining innovation, simplicity, and the valorization of local resources.

Sources

[1] M. A Dweib, B. Hu, R. P. Wool "Bio-based composite roof structure : Manufacturing and processing issues", 2018. https://www.sciencedirect.com/science/article/abs/pii/S0263822305001194

[2] Brahim Mazian et al. "In-depth analysis of Lime-hemp concrete and water vapor interactions : Effect of water default and prediction of the sorption behavior"*, 2025 https://www.sciencedirect.com/science/article/abs/pii/S0958946525000034

[3] Mouatassim Chara et al. "In-structural wall incorporating biosourced earth for summer thermal improvement : Hygrothermal caraterization and building simulation using calibrated PMV-PPD model",2022 https://www.sciencedirect.com/science/article/abs/pii/S0360132322000890

[4] A.Lachheb et al. " Thermal insulation improvement in construction materials by adding spent coffee grounds : An experimental and simulation study", 2019 https://www.sciencedirect.com/science/article/abs/pii/S0959652618335431

Want to learn more about bio-based materials? Feel free to check out our article 'Material Innovation: Cutting-Edge Products for Sustainable Construction' to dive deeper into the topic.