Bio-based Materials: Towards Ecological and Sustainable Construction

In the face of environmental challenges, the construction sector is turning towards more sustainable solutions. Among these, bio-based materials offer a promising alternative to traditional materials such as concrete and steel, whose production is energy-intensive and polluting. The construction industry has a substantial global impact, consuming around 40% of raw materials and responsible for 39% of total CO2 emissions, of which at least 11% comes from manufacturing building materials and products.

Bio-based materials are part of an ecological transition approach, promoting the circular economy and the valorization of local natural resources. This blog post will introduce you to the various types of bio-based materials, their applications, and the reasons for their growing adoption in sustainable construction.

Bio-based Materials: Definition

Definition

According to the United States Environmental Protection Agency, biobased materials refer to products that mainly consist of a substance (or substances) derived from living matter (biomass) and either occur naturally or are synthesized, or refer to products made by processes that use biomass. In the construction sector, bio-based materials refer to materials derived from renewable organic matter (biomass) of plant or animal origin. These materials can be used as raw materials in construction and decoration products, fixed furniture, and as building materials. The focus is on utilizing local resources to promote sustainability and reduce reliance on imported, non-renewable materials.

Sources

“ The 21st century will face a radical paradigm shift in how we produce materials for the construction of our habitat. While the period of the first industrial revolution, in the 18th and 19th century has resulted in a conversion from regenerative (agrarian) to nonregenerative material sources (mines), our time might experience the reverse: a shift towards cultivating, breeding, raising, farming, or growing future resources going hand in hand with a reorientation of biological production methods and goals ”

(D. E. Hebel, F. Heisel, Cultivated Building Materials, Birkhäuser, 2017)

In ASEAN, this paradigm shift with bio-based materials mainly come from the following sectors where resources are abundant making them practical and sustainable choice for construction materials : : 

• Forestry: Bamboo, timber, and other wood derivatives.

• Agriculture: Rice husk, palm oil waste, coconut fiber, hemp, straw, and similar crops.

• Recycling: Recycled cotton, cellulose wadding, and other materials from recycling processes.

Applications

Bio-based materials can be used in various construction applications based on their specific properties:

• Structure and Framework: Bamboo and timber are commonly used for building structures and frameworks, offering excellent mechanical performance and increased durability.

• Insulation: Bio-based insulators such as bamboo fiber, rice husk, cellulose wadding, recycled textiles, and coconut fiber are used for thermal and acoustic insulation of buildings. They are often preferred for their moisture-regulating ability and low environmental impact.

• Coatings and Renders: Lime and hemp-based renders are used for their breathable and insulating properties, promoting a healthy indoor climate.

• Panels and Partitions: Wood fiber panels, hemp bricks, cellulose panels, and rice husk boards are used for interior partitions and wall coverings.

Why Use Bio-based Materials?

Environmental Impact of Traditional Materials

Traditional materials such as concrete and steel are extremely energy-intensive and polluting. After water, concrete is the most consumed product in the world, with 10 billion cubic meters produced annually, equating to more than 1.5 cubic meters per person​​. Cement, the primary component of concrete, is responsible for 8% of global greenhouse gas emissions​​. Sand extraction, crucial for concrete production, also has significant environmental impacts, including the degradation of river and coastal ecosystems and the depletion of natural resources. According to a 2022 UNEP report, 50 billion tonnes of sand, equivalent to one million 15-tonne trucks per day, are extracted annually worldwide​​. Additionally, the extraction of minerals for construction materials like steel contributes to significant environmental and social impacts.

These materials not only require a large amount of energy for their production, but their entire life cycle (from raw material extraction to building demolition) also contributes to a high carbon footprint. For instance, producing one ton of cement emits 264 kg of CO2, while producing one ton of steel emits 694 kg of CO2​.

Carbon Footprint Reduction

Bio-based materials offer an effective solution to reduce the carbon footprint of the construction sector. By using renewable and often local resources, these materials help decrease the greenhouse gas emissions associated with the transportation and processing of construction materials. For example, bio-based materials like wood store carbon during their growth. Wooden buildings can store around 2,000 tonnes of CO2, contributing significantly to reducing global carbon emissions. One ton of wood can store up to 1.8 tonnes of CO2​​.

Furthermore, producing bio-based materials generally generates less CO2 compared to traditional materials. For instance, producing one ton of wood generates only 33 kg of CO2, compared to 264 kg for cement and 694 kg for steel​.

Circular Economy and Waste Valorization

The use of bio-based materials fits into a circular economy approach, where waste from one industry can become raw materials for another. For example, recycling paper to produce cellulose wadding or using recycled textiles for insulation helps reduce the amount of waste sent to landfills and minimizes the extraction of new resources. Agricultural waste valorization is equally important. Materials like hemp and straw, which are by-products of agriculture, can be transformed into construction materials. Utilizing these by-products reduces agricultural waste and the emissions associated with their decomposition or incineration. By promoting the use of locally produced bio-based materials, local economies are supported, and CO2 emissions related to long-distance material transport are reduced. This also stimulates innovation and job creation in the forestry, agriculture, and recycling sectors.

Improving Quality of Life

Bio-based materials significantly improve the quality of life for building occupants. They are generally less polluting, emitting little or no volatile organic compounds (VOCs) harmful to health. For example, studies have shown that some compounds emitted by wood products, such as α-pinene and d-limonene, can have beneficial effects on human health, such as physiological relaxation and reduced blood pressure​​.

Additionally, some of these materials have natural moisture-regulating properties, helping to prevent condensation and mold formation, thereby improving indoor air quality. Their ability to moderate humidity and temperature can help reduce humidity-related respiratory diseases. For example, stabilized earth structures can maintain optimal indoor humidity levels between 40 and 60%, ideal for human health. By using bio-based materials, buildings can offer a healthier and more comfortable indoor environment for occupants, reducing the risks of irritations, allergies, and other health problems related to air quality.

Applications of Bio-based Materials in ASEAN

Bamboo

Bamboo is not only an eco-friendly building material but also an affordable alternative. On average, bamboo construction can be 20-30% cheaper than traditional building methods, making it an accessible option for those on a budget​​. Bamboo species used for building are resistant to insects and fungi, and they are capable of capturing CO2 from the atmosphere. In terms of strength and stiffness, bamboo performs well compared to materials such as steel, concrete, and wood. For floors, furniture, and walls, bamboo plywood can be used. Plywood consists of layered sheets of bamboo made by processing large bamboo stems​​​​.

Bamboo construction systems such as BamCore Prime Wall™ have proven to be twice as strong as conventional 2 x 6 framing for low-rise construction. Additionally, the in-development Mass Timber Bamboo (MTB)™ shows greater rigidity (up to 98% at the same thickness), a slimmer profile (up to 27% thinner while maintaining equivalent stiffness), and reduced weight (up to 17% lighter with similar stiffness) compared to Cross Laminated Timber (CLT).

Rice Husk

Rice husk, a by-product of rice production, is gaining attention as a sustainable material. Ordinary cement is expensive for developing countries, and the need for low-cost building materials is high. Since cement is the most expensive component of concrete, replacing part of the cement with rice husk ash (RHA) would significantly decrease the cost of concrete. It is demonstrated that replacing 50% of cement with RHA can reduce the cost of concrete by 25%​​. A study compared RHA bricks with simple clay bricks and found equivalent properties: absorption test results of 15.27% compared to 20% and compressive strength of 6.2 N/mm² compared to 6.9 N/mm²​​.

Moreover, the use of rice husk for insulation offers a strong thermal performance with thermal conductivity of 0.018 W/mK. Thermal conductivity measures how well a material conducts heat. A lower value indicates better insulation properties. Rice husk has a thermal conductivity of 0.018 W/mK compared to 0.023 W/mK for glass wool for example.

Coconut Fiber

Coconut fiber, also known as coir, is an increasingly popular bio-based material in the ASEAN region due to its abundance and sustainable properties. Derived from the husk of coconuts, coir is known for its durability, resilience, and excellent insulation properties and is the toughest of all the natural fibers. Testing has shown that coir fiber-reinforced concrete is stronger than concrete without coir fiber and has improved mechanical and dynamic properties.

Moreover, the thermal conductivity value changes between 0.040 and 0.050 W/m K for coir fiber–based commercial panels and rolls compared to 0.032 to 0.044 for rock mineral wool in boards and rolls.

Conclusion

Bio-based materials offer a sustainable alternative to traditional materials, reducing greenhouse gas emissions and promoting the circular economy. Bamboo, rice husk, coconut fiber present significant advantages in terms of thermal performance and environmental impact. Today, there are numerous bio-based materials available, making this field an area of continuous innovation. Adopting these materials in construction helps address climate challenges and promotes a more sustainable and responsible future.

Are you interested in integrating bio-based materials into your project? Contact us!