The construction industry, a major source of global emissions, is increasingly looking to nature for solutions. Plant-based materials offer a sustainable path forward, providing greener alternatives to traditional, energy-intensive options like steel and concrete. These natural innovations help create a more environmentally friendly built environment by using renewable resources. They often require less energy to produce and can even store carbon from the atmosphere. Beyond environmental benefits, they open up significant economic and social opportunities, especially for rural communities, and enhance national security by reducing reliance on imported materials.
Hemp, a plant with a long history in building, offers several promising avenues for modern construction and economic growth. It also boosts strategic security by lessening our dependence on energy-hungry and potentially foreign-sourced materials.
Hempcrete, a mixture of the woody core of the hemp plant (hurds), a lime-based binder, and water, is an excellent insulator. It helps regulate indoor humidity and is considered carbon-negative because industrial hemp absorbs a lot of CO2 as it grows, all without needing harmful fertilisers or polluting water sources (1, 2). Growing hemp domestically means we rely less on potentially unstable global supply chains for building materials.
While hempcrete is lightweight and easy to work with, it’s not as strong as traditional concrete, so its use in major structural parts of buildings is limited (3)). The burgeoning hempcrete market, expected to reach USD 25.8 billion by 2024, signifies increasing demand and the potential for new industries and job creation in manufacturing, processing, and construction, often within rural economies. Companies like UK Hempcrete (4) and Hempitecture (5 ) are leading this charge, driven by the demand for sustainable, local building materials that offer thermal efficiency and environmental benefits, all while contributing to national resource independence.
Intriguing research into hemp rebar shows that hemp fibres can be incredibly strong, potentially even stronger than some types of steel (6). Studies suggest that thinner, denser bundles of hemp fibres could have a tensile strength (resistance to being pulled apart) that surpasses even high-strength steel. This “bending and mending strength” could transform structural applications, offering a lighter, rust-proof alternative that requires much less energy to produce than steel.
Developing a strong hemp fibre industry for rebar could create new agricultural markets for farmers and specialised manufacturing jobs in rural communities, boosting local and national economies. The wider industrial hemp sector, which includes uses beyond construction like textiles and biofuels, has significant potential to revitalise rural economies by providing new crop options and local processing facilities, making regions more self-sufficient (7). Government efforts to ease hemp cultivation licensing further acknowledge its economic and strategic value (8). Projects like the University of Exeter study (9) are specifically looking into how farmers can diversify into making plant-based insulation, creating a “harvest to house” system that also helps with rural labour shortages and promotes regional material security.
Adding to hemp’s versatility is HempWood, a patented product made from compressed hemp fibres and a soy-based adhesive (10). Developed by Fibonacci LLC in Kentucky (11), this innovative material offers a sustainable alternative to traditional wood, especially oak. HempWood has similar qualities to oak but is 20% harder and grows much faster, maturing in about 120 days compared to oak’s 50-100 years (10).
By using locally sourced hemp, HempWood’s production process is carbon-negative and produces very few harmful volatile organic compounds (VOCs) (10). Its properties make it a promising substitute for traditional hardwoods in indoor, non-structural uses, reducing reliance on potentially imported timber. Companies like HempWood (11) are pioneering the use of this domestically produced material, strengthening national material security.
Cross-Laminated Timber (CLT), an engineered wood product made by gluing layers of solid wood at right angles (12), provides significant structural strength for walls, floors, roofs, and even large-scale infrastructure like bridges (13). As a substantial “carbon sink” (14), CLT helps fight climate change, and its manufacturing process uses much less energy than that of steel and concrete (15). Sourced from sustainably managed domestic forests (16), the growing use of CLT supports local forestry, timber processing, and specialised manufacturing, often in rural areas.
CLT’s lightweight nature (under half a tonne per cubic meter, significantly less than concrete’s 2.7 tonnes (17)) makes it easier to transport and handle on-site, reducing reliance on extensive transport networks and their associated energy use. Its ability to be prefabricated streamlines construction, leading to faster project completion and potentially lower labour costs. This also creates skilled jobs in off-site manufacturing plants, often near timber-producing regions, which strengthens regional economies. While major global suppliers exist (18, 19), local CLT production can further boost national strategic security.
The SFE (Society of Façade Engineering) Façade 2023 Design and Engineering Awards (20) recognised innovative facade designs that use timber, highlighting the beauty and practicality of domestically sourced plant-based materials in modern construction. The increasing use of timber in facade design shows a growing trend towards sustainable and visually appealing building exteriors, reducing dependence on energy-intensive and potentially imported facade materials.
The shift towards clean construction using materials like CLT can create green jobs in rural areas, including sustainable forestry management, timber harvesting, and operating CLT manufacturing facilities, thereby strengthening local economies and reducing reliance on external labour. Increased demand for sustainably sourced domestic timber can provide new income for landowners and support local economies dependent on forestry, enhancing regional resilience. Initiatives like the Climate Smart Forest Economy Program (21) aim to share knowledge about how forests and forest products can benefit the climate and support the economy and social needs of rural communities, strengthening national energy and resource security.
Beyond timber, agricultural waste products are also finding new uses in infrastructure. For instance, in Brazil, sugarcane waste is being successfully incorporated into road construction. Researchers at the State University of Maringá (UEM) have shown its effectiveness as a replacement for stone dust in asphalt mixtures, improving resistance and helping to reduce costs. This eco-friendly innovation not only embeds carbon waste but also makes roads more durable and contributes to a lower environmental impact. This real-world application, tested on the BR-158 highway, demonstrates a significant way to repurpose biomass into durable and sustainable building materials for large-scale infrastructure, extending the impact of plant-based alternatives beyond traditional buildings (22).
Other diverse examples collectively demonstrate a broader trend: the repurposing of organic waste streams into durable and sustainable building materials, contributing to reduced environmental impact, enhanced resource efficiency, and the creation of new, green industries.
Corn waste, specifically corn cob cores, is being transformed into bio-based tiles and interior wall cladding. This diverts agricultural residue, often destined for burning, into a sustainable alternative for ceramic or less sustainable composite wall materials (30).
Rice husks and straw, abundant agricultural residues, are finding diverse applications, incorporated into various building elements such as bricks, masonry, and green concrete. They offer improved thermal insulation and serve as reinforcement. Studies show their potential in creating highly efficient seals and insulators when bundled, and they can be used in composite materials for walls with good thermal, acoustic, and structural characteristics (31, 32, 33).
Coconut fibres, a byproduct of the coconut industry, are proving valuable, particularly in tropical regions. They can be added to concrete mixes, used as reinforcement for cement-soil bricks, and serve as thermal insulators in building exteriors, effectively absorbing humidity and contributing to passive cooling (33).
The significant carbon footprint of steel production (23), which relies on energy-intensive processes and potentially unstable global supply chains, stands in sharp contrast to the carbon sequestration offered by domestically grown hemp and timber. These plant-based materials require less energy for processing (24). Maximising the use of wood in construction, as seen with CLT, has the potential to remove substantial amounts of CO2 from the atmosphere, helping to meet climate goals and supporting sustainable forest management in rural areas, while boosting national resource independence.
The development of thriving domestic hemp and mass timber industries can create new income streams for farmers and landowners, supporting rural economic diversification and resilience, and reducing reliance on imported construction materials. Government policies and incentives that promote green building materials can further accelerate the adoption of these alternatives, driving demand and fostering innovation across the domestic supply chain. This particularly benefits agricultural and forestry sectors in rural economies and strengthens national strategic security through reliance on local resources.
The potential for carbon sequestration through embedded biomass in construction is truly substantial. Replacing conventional building materials with alternatives that store CO2 could capture as much as 16.6 to 2.8 gigatons of CO2 annually. This is equivalent to about 50% of global CO2 emissions in 2021, showing a huge opportunity for buildings to become major carbon sinks (25). For timber and engineered wood products like CLT, a 70% reduction in embodied carbon can be achieved compared to steel and concrete structures (26). Projections show that substituting conventional concrete floors with CLT panels could lead to a 50 million tonne CO2 equivalent (Mt CO2e) reduction over 30 years (27). Hemp and hempcrete also offer significant carbon storage; building all new homes in the UK with hempcrete walls could potentially save 4.5 million tonnes of CO2 emissions per year (28), with hempcrete itself being carbon-negative (meaning it removes more carbon than it produces) at approximately -34.71 kgCO2/m2 (28). More broadly, for every kilogram of dry plant biomass, about 1.8 kg of CO2 is removed from the atmosphere (28). Despite these impressive benefits, bio-based materials currently make up only about 12% of materials used in the building industry (29).
In conclusion, hemp (including innovative products like HempWood) and CLT are compelling plant-based alternatives in construction. They offer clear performance advantages, significant environmental benefits, and crucial strategic security by reducing reliance on energy-intensive and potentially imported materials. The shift towards greater use of these domestically sourced materials promises substantial economic and social benefits for rural economies, fostering new industries in agriculture, forestry, processing, and manufacturing. This creates green jobs and contributes to a more sustainable, equitable, and strategically secure future for the construction sector and the broader economy. Strategic investment in research, development, and supportive policies will be crucial to unlock the full potential of these innovative building materials and ensure their benefits are realised in both urban and rural landscapes, strengthening national resilience through reliance on home-grown resources.
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