Biobased Materials Explained
What makes a material biobased and when it matters
What biobased actually means
A biobased material is one derived wholly or partly from renewable biological resources - plants, animals, or micro-organisms. In construction, the most common biobased materials are timber, hemp, straw, wool, cork, flax, cellulose (from recycled paper), and various plant-based fibres.
The term describes the origin of the raw material, not the product's environmental performance overall. A biobased material can still have high processing energy, poor durability, or problematic end-of-life characteristics. Being biobased is one attribute, not a complete sustainability assessment.
On Matera, products with biobased sourcing are identified by a teal 'Bio-based' badge on their sourcing tab, derived from the supplier's verified sourcing data.
Carbon implications of biobased materials
Biobased materials have a distinctive relationship with carbon. Plants absorb CO₂ as they grow, storing it as carbon in their cellular structure. When that plant material is used in construction, the stored carbon is locked into the building for its service life.
This stored carbon is called biogenic carbon. It is accounted for separately from fossil carbon in lifecycle assessments because it behaves differently - it was recently removed from the atmosphere (during plant growth) rather than released from geological stores (during fossil fuel combustion).
EPDs report biogenic carbon separately. Some show a negative A1 value (representing CO₂ absorbed during growth) followed by a positive C3/C4 value (representing CO₂ released at end of life through decomposition or incineration). Others report it as a separate line item outside the main GWP total.
Watch out. Biogenic carbon accounting is complex and methodologies vary between EPD programme operators. A negative embodied carbon figure based on biogenic carbon storage is not the same as genuinely zero-emission manufacturing. Always check whether biogenic carbon has been netted off or reported separately.
Common biobased materials in construction
The range of biobased construction materials has expanded significantly in recent years. These are the most established options.
Timber
The most widely used biobased structural material. Softwood and hardwood.
Wood fibre insulation
Processed from wood chips or sawmill residues.
Hempcrete
A lime-and-hemp composite for infill walls and insulation.
Cellulose insulation
Made from recycled newsprint treated with fire retardant.
Cork
Bark harvested from cork oak trees without felling.
Sheep wool
Natural fibre with good thermal and acoustic performance.
Performance considerations
Biobased materials have real performance strengths, but also limitations that need to be designed for.
| Topic | Detail |
|---|---|
| Moisture management | most biobased materials are hygroscopic (they absorb and release moisture). This can be an advantage for indoor air quality and condensation control, but requires careful detailing to avoid sustained wetting that leads to degradation. |
| Fire performance | untreated biobased materials are generally combustible. Many can achieve acceptable fire ratings with treatment or appropriate build-up design, but this must be engineered and specified correctly. |
| Durability | biobased materials can be very durable when properly detailed (timber buildings have lasted centuries), but they are vulnerable to biological attack (rot, insects) if moisture and ventilation are not managed. |
| Dimensional stability | natural fibres can expand and contract with humidity changes. Engineered products (glulam, CLT) are more stable than solid timber, but movement should still be accommodated in design. |
| Supply chain maturity | some biobased materials (timber, cork) have well-established supply chains. Others (hempcrete, straw bale) may have longer lead times and fewer suppliers. |
How to evaluate a biobased product
Being biobased is a starting point, not an endpoint. These questions help you assess whether a biobased product is genuinely a good choice for your project.
- Does it meet the functional requirement? Thermal performance, structural capacity, fire rating, and acoustic performance must be confirmed independently of the material's origin.
- What does the EPD say? Compare A1–A3 production-stage carbon with conventional alternatives at the same functional unit. Check whether biogenic carbon is netted off or reported separately.
- Is the raw material sustainably sourced? Timber should have FSC or PEFC chain of custody. Hemp and other crops should ideally come from managed agricultural systems without significant land-use change.
- What happens at end of life? Can the material be reused, composted, or recycled? Or will it go to landfill or incineration? Module D and C-stage data in the EPD will tell you.
- Is the supply chain reliable? Can the supplier deliver the required quantities on programme? Is the product available from multiple sources or dependent on a single manufacturer?
Biobased vs natural vs sustainable
These terms are related but not interchangeable, and it is worth being precise.
Material origin
Derived from biological resources. A factual description of where the material comes from.
Processing level
Minimally processed and free of synthetic additives. Says nothing about sourcing.
Overall judgement
A broader claim about environmental and social impact. Requires evidence to support.
Note. On Matera, the 'Bio-based' badge specifically indicates the source type of the material as verified through sourcing data. It is a factual label about origin, not a value judgement about overall sustainability.
Useful links
Standards & schemes
Related guides
Wood Fibre Insulation
A low-impact alternative to PIR and mineral wool
Recycled Content Explained
What the percentages mean and how to compare them fairly
Embodied Carbon Explained
What it is, why it matters, and how to reduce it through better material choices
Low-Carbon Material Substitutions
Practical swaps that reduce embodied carbon without compromising performance