Embodied Carbon and Material Selection
Ten building material categories worth investigating when seeking to reduce embodied carbon — and the product data, performance requirements and project conditions that should be verified before specifying them.
No building material is automatically low carbon in every project. Its embodied carbon depends on the product, the quantity used, how and where it is manufactured, the distance it travels, how long it lasts and what happens at the end of its useful life.
The following ten material categories are therefore not universal answers. They are practical areas for Australian architects, builders, developers and sustainability teams to investigate when seeking to reduce the material-related emissions of a building.
A credible material decision should consider equivalent performance, project-specific quantities, transport, durability, replacement and verified environmental data rather than relying on broad terms such as green, natural or carbon-negative.
In Brief
Lower-Carbon Material Selection Starts Before Product Substitution
Retain and Reduce
Retaining existing construction and reducing unnecessary material may provide a greater benefit than replacing one new product with another.
Compare Like with Like
Products should be compared using equivalent structural, thermal, fire, acoustic, durability or functional performance.
Verify the Outcome
Environmental Product Declarations, applicable emissions factors and project quantities help move the decision beyond general sustainability claims.
The most appropriate material is not necessarily the product with the lowest isolated carbon figure. It is the option that delivers the required building function with an appropriate quantity, service life and whole-building outcome.
Understanding the Result
What Makes a Building Material Lower in Embodied Carbon?
Embodied carbon describes greenhouse gas emissions associated with building materials and construction processes. Depending on the scope of an assessment, this may include raw material extraction, manufacturing, transport, construction, maintenance, replacement, demolition and end-of-life processing.
A product may have lower embodied carbon because it requires less energy to manufacture, contains reused or recycled inputs, replaces a more emissions-intensive product, uses fewer raw materials or remains serviceable for longer.
Important Comparison Rule
Compare materials according to the function they perform, not simply according to their weight.
Comparing one kilogram of insulation with one kilogram of another insulation product may be misleading if the products provide different thermal resistance, density, fire performance or durability. Credible comparisons should use an equivalent functional unit and a consistent lifecycle boundary.
Principle 01
Use Less
Efficient structural grids, simplified assemblies and reduced finishes can lower impacts before an alternative material is introduced.
Principle 02
Use It Longer
Durable, repairable and adaptable materials may reduce refurbishment and replacement impacts over the life of the building.
Principle 03
Verify the Result
Product-specific data, project quantities and consistent lifecycle assumptions are needed to substantiate lower-carbon claims.
Before Product Substitution
Retain, Reduce, Reuse, Optimise, Substitute and Verify
Material substitution often receives the most attention, but it is not always the most effective first step. A useful decision sequence is:
Materials at a Glance
10 Low Embodied Carbon Building Materials to Consider
Material 01
Reused and Reclaimed Materials May avoid new manufacturing and reduce demand for virgin raw materials.Material 02
Lower-Carbon Concrete Can reduce emissions associated with cement content and overall material volume.Material 03
Lower-Emissions Steel Recycled content and alternative production routes may reduce carbon intensity.Material 04
Responsibly Sourced Timber Renewable feedstocks and structural substitution may lower project impacts.Material 05
Lower-Impact Masonry Reuse, recycled inputs and different manufacturing processes may reduce impact.Material 06
Earth-Based Materials Limited processing and local sourcing may support a lower-impact wall system.Material 07
Bio-Based and Recycled Insulation Renewable or recovered inputs may reduce manufacturing impacts.Material 08
Lower-Impact Flooring and Finishes Durable renewable or recycled products may reduce replacement impacts.Material 09
Recycled-Content Sheet Products Can reduce virgin inputs and support construction-waste recovery.Material 10
Recycled-Content Metals Recycled feedstock may reduce energy-intensive primary production.Material 01
Reused and Reclaimed Materials
Reuse can be one of the most direct ways to reduce demand for newly manufactured construction products. Reclaimed bricks, structural timber, steel sections, stone, flooring, doors, fixtures and façade components may retain value beyond their original application.
The embodied carbon benefit comes primarily from avoiding or delaying new production. However, reused materials are not impact-free. Removal, cleaning, testing, refurbishment, storage and transport can all affect the result.
Reuse should also be coordinated with structural, fire, acoustic, durability and certification requirements. The most effective opportunities are often identified early, while the design can still respond to available dimensions and quantities.
What to verify: Provenance, condition, remaining service life, structural or performance testing, refurbishment requirements, transport distance and whether the design can use the material efficiently.
Material 02
Lower-Carbon Concrete
Concrete can make up a substantial proportion of a building’s material volume. Reductions can come from using less concrete, optimising structural spans and slab thicknesses, reducing cement or clinker content, using suitable supplementary cementitious materials and selecting products with verified lower emissions.
Terms such as green concrete are broad marketing descriptions rather than a single technical standard. The actual result depends on the mix, strength class, curing requirements, available materials, structural performance and manufacturing location.
A lower-carbon mix should be assessed against a suitable reference mix providing equivalent performance. Early engagement with the structural engineer and concrete supplier is important because mix availability and technical constraints differ between projects and regions.
What to verify: Cement or clinker content, supplementary cementitious materials, required strength, curing time, supplier availability, transport and a product-specific or otherwise applicable EPD.
Material 03
Lower-Emissions Steel
The embodied carbon of steel varies according to the production route, recycled content, energy source and manufacturing efficiency. Products made with higher recycled content or lower-emissions electricity may offer reduced carbon intensity compared with conventional alternatives.
Material efficiency remains equally important. Rational structural grids, efficient member sizing, reduced over-specification and designing for future disassembly can reduce the total quantity of steel required.
The term green steel should not be relied on without supporting evidence. Product-specific data should confirm that comparisons use equivalent grades, strength and fabrication requirements.
What to verify: Manufacturing route, recycled content, electricity source, grade, fabrication impacts, structural quantity, sourcing and verified product emissions.
Material 04
Responsibly Sourced Timber and Mass Timber
Timber is a renewable building material and may provide a lower-carbon alternative in some structural, framing, lining and finishing applications. Engineered products such as cross-laminated timber, laminated veneer lumber and glulam can also allow timber to perform roles traditionally served by steel or concrete.
Timber is not automatically the lowest-carbon solution. The result depends on forest management, processing, adhesives, transport, moisture protection, durability, construction waste and the method used to account for stored biogenic carbon.
Design teams must also consider fire performance, termite risk, acoustic requirements, connection systems and exposure conditions. Responsibly sourced timber used efficiently and protected for a long service life is generally more credible than relying on carbon-storage claims alone.
What to verify: Responsible sourcing certification, product EPD, adhesives, durability, fire and moisture strategy, expected service life and the treatment of biogenic carbon.
Material 05
Reclaimed or Lower-Impact Masonry
Reclaimed bricks and stone can reduce demand for newly manufactured masonry while retaining materials with a long remaining life. New masonry products may also achieve lower impacts through recycled content, lower-temperature manufacturing, renewable energy or optimised material use.
The complete wall system should be considered rather than the masonry unit alone. Mortar, reinforcement, finishes, wall thickness, thermal performance, transport and construction waste can materially affect the result.
Reclaimed bricks may require cleaning, sorting and testing, particularly where structural performance or weather exposure is important. Their dimensional and visual irregularity also needs to be accepted as part of the design.
What to verify: Compressive strength, durability, mortar requirements, cleaning, transport, moisture exposure, thermal performance and product-specific environmental data.
Material 06
Earth-Based Materials
Rammed earth, compressed earth blocks and other earth-based systems can require relatively little processing when suitable material is available close to the project. They can also provide thermal mass and a durable internal or external finish.
Their carbon performance is highly project-specific. Cement stabilisation, long transport distances, thick wall sections, structural requirements and protective coatings may increase embodied impacts.
Thermal mass is also not automatically beneficial in every climate, orientation or occupancy pattern. Earth construction should be evaluated as a complete wall system that meets structural, moisture, insulation and weathering requirements.
What to verify: Source distance, stabiliser content, total material volume, structural design, insulation needs, moisture protection, workmanship and applicable construction requirements.
Material 07
Bio-Based and Recycled Insulation
Cellulose, wood fibre, cork, hemp-based products and insulation containing recycled material may provide alternatives to more emissions-intensive products. Some use renewable or recovered feedstocks and may require less manufacturing energy.
Insulation should always be compared on equivalent thermal performance. The quantity required to achieve a particular R-value can vary significantly between products. Density, installation quality, compression, air leakage, moisture behaviour and service life may also affect real building performance.
Hempcrete is sometimes described as carbon-negative, but this should not be treated as a universal property. The result depends on the binder, density, transport, construction method, lifecycle scope and the treatment of biogenic carbon.
What to verify: Installed R-value, density, fire performance, moisture resistance, additives, binders, durability, installation requirements and comparable EPD data.
Material 08
Lower-Impact Flooring and Finishes
Flooring and internal finishes cover large areas and may be replaced several times during a building’s life. Cork, linoleum, responsibly sourced timber, reclaimed flooring and products containing recycled content may reduce embodied impacts where they are durable and appropriate for the intended use.
Product selection should extend beyond the primary material. Adhesives, sealants, coatings, underlays, subfloor preparation, maintenance and replacement frequency may influence the total lifecycle result.
A durable product with a moderately higher initial impact may outperform a lower-impact product that requires frequent replacement. Indoor air quality should be assessed separately rather than assumed from embodied carbon alone.
What to verify: Expected wear life, maintenance, coatings, adhesives, replacement frequency, recycled or renewable content, repairability and product-specific emissions data.
Material 09
Recycled-Content Plasterboard and Sheet Products
Plasterboard, fibre cement, acoustic panels and other sheet products are widely used across residential and commercial buildings. Products incorporating recovered gypsum, recycled fibres or manufacturing waste may reduce virgin material demand.
Because these products are often used over large surface areas, small improvements per square metre can become meaningful at the building scale. Efficient layouts and standardised dimensions can also reduce cutting waste during construction.
Some manufacturers provide collection or take-back programs for clean offcuts. Their actual benefit depends on local availability and whether returned material is genuinely recycled into new products.
What to verify: Recycled content, board thickness, durability, manufacturing energy, construction waste, local recycling pathways and applicable EPD information.
Material 10
Recycled-Content Aluminium and Metal Products
Aluminium, steel and other metals are used in roofing, façades, windows, framing, fixtures and building services. Producing metals from recycled feedstock can require substantially different processes from producing them from virgin raw materials.
The benefit depends on the actual recycled content, manufacturing energy, alloy, finish, fabrication and transport. Aluminium in particular can have a wide range of embodied carbon results depending on the electricity used during production.
Long service life, corrosion resistance and recyclability can support a better lifecycle outcome, but these attributes do not remove the importance of reducing material quantities and avoiding unnecessary decorative or layered systems.
What to verify: Recycled content, production energy, alloy, coating, fabrication, transport, expected service life and product-specific EPD data.
Emerging Material Systems
What About Emerging Materials Such as Mycelium?
Emerging bio-composites such as mycelium-based products may eventually provide useful lower-impact alternatives in selected non-structural applications. Their potential can come from renewable feedstocks, low-temperature manufacturing and the use of agricultural residues.
Commercial readiness varies considerably. Fire performance, moisture resistance, coatings, durability, structural capacity, manufacturing scale and verified environmental data must be examined for each product and application.
Read our detailed guide to mycelium bricks and mycelium-based building materials .
Product Data
How to Compare Materials Using an EPD
An Environmental Product Declaration, or EPD, presents environmental impact data for a product using defined assessment rules. EPDs can improve transparency, but the presence of an EPD does not automatically mean that a product is low carbon or environmentally preferable.
Before comparing two EPDs, check that the products perform an equivalent function and use compatible declared or functional units. The lifecycle modules should also align.
A negative result in one lifecycle module should not be interpreted as proof that the entire product, building element or completed building is carbon-negative.
Whole-Building Context
Material Choice Is Only Part of the Building Result
A lower-carbon product does not automatically produce a lower-carbon building. The total outcome is shaped by the quantity of material used, the structural system, transport, construction waste, durability, maintenance, replacement and end-of-life assumptions.
Operational performance also remains important. Removing insulation, glazing performance or shading solely to reduce upfront material impacts could increase energy use and operational emissions over the building’s life.
Embodied and operational carbon should be considered together rather than treated as competing objectives.
Project Review
Australian Low-Carbon Material Checklist
Frequently Asked Questions
Low Embodied Carbon Material FAQs
What building material has the lowest embodied carbon?
There is no single lowest-carbon building material for every project. Results depend on the required function, quantity, product specification, manufacturing process, transport, durability and lifecycle scope. Retaining or reusing an existing material may provide a lower impact than purchasing any new alternative.
Is timber always lower carbon than concrete or steel?
No. Timber may provide a lower-carbon solution in some applications, but the result depends on sourcing, processing, adhesives, transport, durability, fire and moisture requirements, structural efficiency and the method used to account for biogenic carbon.
Is hempcrete carbon-negative?
Hempcrete should not be universally described as carbon-negative. Results vary according to cultivation, binder composition, density, transport, construction method, lifecycle boundaries and assumptions about stored biogenic carbon and end-of-life treatment.
Does recycled content always mean lower embodied carbon?
Not necessarily. Recycled content can reduce virgin material demand, but collection, sorting, processing, energy use, transport and product performance also influence the result. Verified product data provides a more reliable basis for comparison.
Which insulation materials may have lower embodied carbon?
Cellulose, wood fibre, cork, hemp-based products and insulation containing recycled material may have lower embodied carbon than some alternatives. Products should be compared using equivalent installed R-values while also considering density, fire, moisture, durability and installation requirements.
Are locally sourced materials always lower carbon?
Local sourcing may reduce transport emissions, but manufacturing impacts can remain more significant. A locally manufactured high-impact product may still have greater embodied carbon than a more efficient product transported from further away.
Does an EPD prove that a product is sustainable?
No. An EPD provides structured environmental information. It does not certify that a product is sustainable, low carbon or preferable in every application. The data must be interpreted within the context of the project.
When is an Embodied Carbon Report useful?
An Embodied Carbon Report is useful when a project team needs to quantify material-related emissions, identify carbon hotspots, compare design options or support a formal sustainability, planning or rating requirement.
Related Guidance
Continue Exploring Embodied Carbon
Embodied Carbon Project Review
Understand Where Material-Related Emissions Are Concentrated
Material selection is most useful when product data, quantities, structure, sourcing and lifecycle assumptions are assessed together. An Embodied Carbon Report can identify the largest sources of impact and test whether proposed design or specification changes materially improve the project outcome.
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