At present, concrete and steel, the two most widely used materials in construction, account for around 11% of global CO₂ emissions due to embodied carbon. This means that to effectively decarbonise, the construction industry must look for green alternatives.
At CFP Energy, we're committed to helping our clients in construction decarbonise. With over 20 years’ experience in the energy sector, we can help you access biofuels to power your fleet, or help you access power purchase agreements (PPAs) and voluntary carbon credits to reduce your Scope 2 emissions and offset residual carbon from materials and operations.
Contact our team to see how we can help you start decarbonising your business today.
What Are Low Carbon Materials?
Low-carbon materials are construction-specific products designed to reduce the amount of carbon released over their entire lifecycle - from the initial stage when raw material is extracted, all the way through to manufacturing, transport, installation, and disposal.
Before entering the transport and utilisation phase, the carbon profile of construction materials can be reduced in their production stage by using waste products or recycled matter. For instance, stone used for masonry can be produced using recycled aggregates.
These ‘green aggregates’ are typically made by reprocessing materials that might have come from a demolished building or be excess or waste from another project.
What are Examples of Low Carbon Products?
The number of low carbon materials in construction is, in practice, quite extensive. This section will outline some of the most common materials of this kind currently being used in the building sector.
Sustainable Timber
The main benefit of timber is its ability to store carbon - a property of wood that makes it an ideal sustainable material. When sourced and harvested sustainably, i.e., when the timber is extracted from FSC-certified forests, timber can potentially keep on storing carbon, all throughout the building's lifespan.
Cross-laminated timber (CLT) has similar applications because of its impressive carbon sequestration properties. Made from sections of timber that are glued, or ‘cross-laminated’, together, each cubic metre of timber typically stores around 0.9 tonnes of CO₂.
To ensure the material has been sourced responsibly - that is, extracted using sustainable methods - certification schemes like FSC and PEFC are essential to avoid deforestation.
Lower-Carbon Concrete and Cement
Conventional Portland cement production is notoriously carbon-intensive. For instance, calcination - a process that turns aggregates like limestone and clay into clinker that is used in cement - is energy intensive, making up 50-60% of cement’s total CO₂ emissions.
However, alternative cement formulations can significantly reduce these emissions. Ground granulated blast furnace slag (GGBS), for example, is a byproduct of steel production.
It can perform the same function as Portland cement, without requiring the powering of furnaces that produce amounts of energy sufficient to release significant amounts of CO₂.
- Fly ash, a by-product of coal-powered furnaces, can also be used as a cement substitute.
- Recycled concrete aggregates help reduce the need for new raw materials.
- New cement chemistries using calcium silicate or magnesium-based binders can absorb CO₂ as they cure, representing a promising new area of innovation.
Materials with High Recycled Content: What Are the Low Carbon Resources?
Steel, the most commonly used material in construction, is another product that requires high amounts of energy in its production. By using scrap steel as primary feedstock, however, recycled steel can reduce the thermal energy use of steel by as much as 75%.
Concrete and cement, meanwhile, can claim similar reductions by using recycled aggregates, sourced from construction waste, instead of virgin stone and gravel in their creation.
Recycling concrete aggregate, for instance, results in 10-30% fewer CO₂ emissions compared to natural stone aggregate by omitting energy-intensive activities like quarrying.
Bio-Based Materials
Hemp-based construction materials can be used across a range of applications, from insulation and weatherproofing, and due to their reliance on organic feedstocks, possess enhanced sustainability credentials over building products based on artificial substrates.
Hempcrete, for instance, is a concrete substitute that combines hemp fibres with more traditional substrates like lime to create a building material that continues to absorb CO₂ throughout its life cycle.
Straw bale construction also delivers exceptional insulation properties. Despite being an agricultural waste, straw has many practical uses and can even be recycled and used as a building material. This ensures that less CO₂ is created by artificial materials and that no CO₂ is wasted in disposing of the straw in cases where the straw is not reused.
Cork represents another naturally occurring material with sustainable characteristics. With the unique capacity to regenerate its outer bark, and with inherent insulating and fire-resistant properties, cork makes an ideal material for building offices, studios and homes.
Benefits and Considerations
Key Advantages
The reduced embodied carbon represents the primary advantage of the materials covered in this article. Buildings constructed with these alternatives can achieve 50-80% reductions in embodied carbon emissions compared to conventional construction methods.
But there are co-benefits to using materials like waste steel and blast furnace slag: material that might be potentially wasted is reutilised, ensuring that energy-intensive disposal methods - such as burning or transporting to landfill - are avoided, helping to maximise resource efficiency while minimising environmental impact throughout the supply chain.
There are also performance characteristics to consider - characteristics that go far beyond the low carbon profile many of these materials exhibit. Timber structures, for instance, exhibit excellent seismic resistance properties, while cork-based insulation provides a form of humidity control far more cost-effective than electrically powered alternatives.
Key Considerations
Despite the obvious benefits of low carbon construction materials - as verified by Life-Cycle Assessment (LCA) Verification standards - responsible sourcing is crucial. Third-party certifications like these provide the assurance where first-hand vetting isn’t possible.
In addition, because manufacturers sometimes overstate the environmental gains of certain materials, assessments should be carried out through independent inspections. Tests like these may be carried out through the BRE (Building Research Establishment) in the UK, which tests according to ISO 14025 standards, or the SGS (Société Générale de Surveillance), where materials are also tested to rigorous ISO standards.
Finally, it is important to factor in the cost implications of low carbon construction materials. Although initial premiums can be a barrier to adopting certain materials - like geopolymer and recycled aggregates - life-cycle cost analysis often shows that these materials provide comparable or even better performance long term, making them a long-term investment.
The Path Forward
Having explored the question “what are low carbon materials?”, the case for incorporating low carbon design and implementation in construction is now hopefully clear.
The built environment must transform rapidly to meet internationally ratified climate targets, and this will require commitment and collaboration across many fields - from manufacturing to construction and policy and governance.
At CFP Energy, we're committed to helping our clients in construction decarbonise. With over 20 years’ experience in the energy sector, we can help you access biofuels to power your fleet, or help you access power purchase agreements (PPAs) and voluntary carbon credits to reduce your Scope 2 emissions and offset residual carbon from materials and operations.
Contact our team to see how we can help you start decarbonising your business today.
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