Using environmentally friendly construction materials
As the construction industry strives to meet net zero targets, contractors seek to reduce embodied carbon to increase the sustainability of their projects.
Planning to use greener construction materials such as EAF steel helps to reduce embodied carbon.
‘Embodied carbon’ refers to the emissions created by the construction process. The sourcing, transport, and erection of materials to construct a building. It also includes the deconstruction and recycling or reuse of materials at a building’s end-of-life.
Structural Steel is evolving to become greener
Steel is one of the most environmentally friendly construction materials because it is resilient, long-lasting, and infinitely recyclable. However, there are two main processes for manufacturing steel, and they have different sustainability credentials.
- Basic oxygen steel making route (Bf- BOF) uses raw materials in a gas furnace.
- Electric arc furnace (EAF) route melts scrap steel in an electric arc furnace.
Using recycled steel reduces CO2 emissions by 58%
All steel is recyclable, but if you want to know more about reducing embodied carbon with greener steel, you need to use EAF steel where possible. It is made from up to 100% scrap steel that’s melted in an electric arc furnace. This process does not produce any harmful greenhouse gasses or environmentally hazardous by-products. It also has improved efficiency compared to a blast furnace.
Overall, EAF steel manufacturing is a more flexible process that results in a reduced amount of embodied carbon. In fact, using scrap steel instead of virgin ore reduces CO2 emissions by 58%. Recycling one tonne of steel saves 1.4 tonnes of iron ore, 0.8 tonnes of coal and 0.3 tonnes of limestone and additives and 1.67 tonnes of CO2.
Getting closer to net zero steel
ArcelorMittal can go one step further in decarbonising steel by manufacturing with renewably produced electricity. XCarb® is their label for recycled and renewably produced steel.
Whilst EAF steel can be made with wind and solar energy from a grid that is local to the factory, it’s still not yet net zero. Nevertheless, it’s a huge step in the right direction.
Here you can see the difference in carbon per tonne of finished steel:
BOS = 2.5t.
EAF= 0.5t.
XCarb = 0.333t.
In the future, it looks like more products will be made from EAF steel, but there is only so much scrap in circulation.
The data from green hydrogen pilot projects will play a role in influencing future actions for the industry to achieve net zero targets by 2050.
Working with sub-contractors to reduce embodied carbon
More than half of the world’s carbon emissions come from fossil fuel use. This is another reason why EAF steel is a critical technological pathway for decarbonizing construction projects.
A steelwork contractor will be able to advise how you can reduce embodied carbon with greener steel, including which parts of your structure can be fabricated with EAF steel.
It’s estimated that 60 to 70% of a typical project’s steelwork can be made using the EAF manufacturing process. It’s not possible to manufacture certain parts in EAF steel and the steel fabricator will be able to advise on this.
They may also be able to minimise the environmental impact of the construction process. Early contractor involvement is key for discussing and improving environmental impacts during the planning and costing stage of projects.
Whole life carbon assessments
This includes the emissions generated from construction, use and demolition and disposal. For more information on designing to reduce embodied carbon, see our article: Reducing embodied carbon in structural steel. This explains why module D in embodied carbon calculations is essential if benchmarking steel’s carbon footprint against its construction counterparts.
Completing WLCAs on all projects is now essential, to build evidence and understanding of the construction and built environment sectors’ carbon emissions. And since it’s estimated that 80% of the built environment we’ll be using in 2050 is already built, new solutions will need to extend to retrofitting existing building stock.
For contractors delivering at construction stage, this requires circular economy principles, to:
- Build less – prioritising refurbishment of existing stock or reuse of materials
- Build light – considering the impact of a building’s structure
- Build wise – understanding a building’s longevity and local context.
- Build low carbon – reviewing building material’s specifications and whole-life carbon
- Build for the future – understanding a building’s adaptability or recyclability at end-of-life
- Build collaboratively – involving all contractors; as with the ‘golden thread’
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