Embodied carbon: comparisons between the UK and Australia

Muiris Moynihan, Chair of the Institution’s Sustainability Panel, moved from the UK to Australia in early 2024; in this blog post, he explores the key differences in embodied carbon he has noticed in Australia, and what that means for effective decarbonisation down under.

Steel: more carbon-intensive (for now)

Steel production in Australia has a higher carbon footprint compared to the UK (e.g. 3.72kgCO₂e/kg¹ for hot-rolled sections in Australia against 1.13 kgCO₂e/kg in Europe²). This is due to a greater proportion of blast-furnace production (powered by fossil-fuels) and a more carbon-intensive electricity grid (0.62 kgCO₂e/kWh³ vs. 0.177 kgCO₂e/kWh⁴). Even where low-carbon steels are imported, these can have higher associated carbon due to the long shipping distances. 

On the bright side for Australia however:

• A major Government effort is underway⁵ to increase electricity generation from renewable sources, thereby reducing the carbon intensity of the grid (and hence steel production)
• There are a number of consortia (for example⁶ aiming to build new electric arc furnaces in Australia to supply more ‘green steel’ into the market – so watch this space!

Concrete: lots of potential 

Concrete is another material with notable differences between the two regions: 

• In the UK, there are established industry-wide benchmarks for low-carbon concrete⁷, and initiatives like ConcreteZero commit businesses to using 100% low-carbon concretes by 2050⁸
• Australia is earlier in its concrete decarbonisation journey, as evidenced by the higher average carbon content reported⁹ as compared with the UK low-carbon concrete⁷. There is a greater availability of pulverised fly ash (PFA) whilst the use of ground granulated blast furnace slag (GGBS) is less common. The supply chain for low-carbon concrete is still developing, and price premiums for low-carbon concrete can still exist, depending on the concrete strength grade and the level of carbon reduction sought. This may change however as the supply-chain becomes more efficient at exploiting the stockpiles of fly ash, with research ongoing to determine how more of it can be used as cement replacement

Timber: increasing domestic production and experience

Until recently, both glulam and cross-laminated timber had to be imported into Australia, which added significant embodied carbon due to shipping. Now, some of these products can be sourced domestically and the supply of engineered timber products is growing¹⁰. Since these materials are relatively new in Australia, expertise in designing and constructing with them is not as widespread as in the UK. However, there is a growing interest in their use.

Transportation emissions: bigger down under

The vast distances to and within Australia make transportation emissions a more significant factor compared to the UK. The carbon footprint of transporting materials into and across the country can be substantial, adding to the overall embodied carbon of construction projects. In contrast, the UK's smaller geographical size and closer proximity to European and American suppliers means transportation carbon impacts for UK projects are lower than in Australia.

Circular economy: also bigger down under

In part due to Australia’s geographic isolation, there has long been an economic driver to reuse and recycle materials to reduce imports. This has manifested in policies like the state of Victoria’s ‘Recycled First’ approach¹¹, where construction projects are required to incorporate waste streams such as tyre rubber, post-consumer plastic and crushed glass into asphalt, pipes and sand respectively. Creating this demand has in turn spurred research and innovation, identifying new opportunities for the circular economy.

Regulatory landscape: federal pros and cons

The federal nature of Australia is both a boon and a hindrance to embodied carbon reduction. State governments are politically and fiscally semi-autonomous, meaning they can pursue different sustainability agendas to the federal government, often ones that are more aligned to their own needs. For example, the Western Australia government is interested in how lower-carbon steel can be made from its iron ore, whilst Victoria has focussed on recycling. The states also learn from and support each other, for instance New South Wales has taken the lead in developing construction product carbon libraries, these are now being extended and adopted nationally¹².

On the flip side, each state has its own regulations – meaning a low-carbon innovation approved for use in one must still get approved in others. Whilst “Buy Local” clauses in public contracts can spur use of nearby, low-carbon products, they can also prevent the use of solutions from overseas or out-of-state.

Conclusion: what does this mean for decarbonisation?

Whilst both the UK and Australia are working towards reducing embodied carbon in construction, the differences in material availability, production methods, transportation routes, economies and regulatory landscapes present unique challenges and opportunities for each region. Therefore, whilst both countries can (and should) learn from each others’ experiences, an engineer should be aware that not all techniques and solutions can be imported without due consideration. In particular:

• Given embodied carbon in steel (particularly) and concrete is generally higher in Australia than the UK, the benefits of designing out those materials wherever possible is even more impactful
• Additionally, comparing between the carbon contents of otherwise identical structural options – e.g. floor slab systems – may give different optimum solutions due to the relative differences in materials’ embodied carbon between the two countries
• The relative novelty of some engineered timber products in Australia may mean extra consultation is required when designing and constructing with them, as they may be unfamiliar to some project team members
• The relative isolation and size of Australia mean that transport emissions (importing materials to Australia and distributing them within the country) can be substantially larger than those for UK projects, and should therefore be explicitly calculated. However, Australia’s isolation also means that circular economy initiatives are actively promoted
• The federal nature of Australia means that innovation is more tailored to local needs, and that lessons can be learned by looking across state boundaries. It’s also worth remembering that specifications and techniques approved in one state or territory may require extra time and engagement to be approved elsewhere, which should be factored into project programmes when aiming to spread best practice or innovations

References
[1] https://epd-australasia.com/wp-content/uploads/2018/04/IB-Steel-Centre-Hot-Rolled-Structural.pdf 
[2] https://www.istructe.org/journal/volumes/volume-98-(2020)/issue-7/a-brief-guide-to-calculating-embodied-carbon/
[3] https://www.dcceew.gov.au/climate-change/publications/national-greenhouse-accounts-factors-2025 [National value used from Table 1]
[4] https://www.gov.uk/government/publications/greenhouse-gas-reporting-conversion-factors-2025 [UK electricity value used]
[5] https://www.dcceew.gov.au/climate-change/emissions-reduction/net-zero/electricity-and-energy-sector-plan
[6] https://www.greensteelwa.com.au/
[7] https://www.lccg.uk/home/current-activities/lccg-market-benchmark 
[8] https://www.theclimategroup.org/concretezero
[9] https://mecla.org.au/wg5b/
[10] https://mecla.org.au/engineered-timber-products/ 
[11] https://bigbuild.vic.gov.au/about/ecologiq/recycled-first-policy 
[12] https://www.nabers.gov.au/publications/national-emission-factors-database