How to minimise embodied carbon in steel structures

Using suppliers’ expertise to deliver sustainable construction



The UK’s construction industry was a world leader in identifying the impact of emissions created by construction. So we must now also be leaders in tackling and reducing emissions to meet global net zero targets.


Construction and the built environment are responsible for around 39% of global greenhouse emissions, including generating 11% during the construction process alone.


Embodied carbon is the emissions created by the construction process – the sourcing, transportation and erection of materials to construct a building, and the deconstruction and recycling or reuse of materials at a building’s end-of-life.


The remaining 28% of emissions comes from operational carbon – the greenhouse gases emitted during day-to-day use of buildings – the energy used to power, light, heat and cool properties.


The construction industry has dual responsibility for designing buildings that produce minimal operational carbon and delivering sustainable construction projects that minimise embodied carbon creation. While significant steps are being taken to reduce operational carbon, to meet targets for net zero carbon emissions by 2050, embodied carbon should not be overlooked by clients and contractors.


Calculating embodied carbon


Embodied carbon is calculated using a lifecycle assessment (LCA) and can be ascertained most accurately by using all four modules of an LCA:


  • Module A: How and from where raw materials or products are sourced, produced, transported and erected;
  • Module B: How much energy a building requires for day-to-day usage;
  • Module C: How a building is processed and deconstructed at its end-of-life;
  • Module D: How materials and components can be recovered, reused or recycled at a building’s end-of-life.


Measuring the associated emissions using these allows the most comprehensive calculation to be found.


Benchmarking average embodied carbon


A joint study by the British Constructional Steelwork Association (BCSA) and the Steel Construction Institute (SCI) found the average emissions factor for structural steel in UK construction. It shows that on average 1.74 tonnes of CO2 is emitted per tonne of steel (tCO2e/t) for Module A. This is a blended ratio between blast furnace and EFA material. However, factoring in Module D, reduces this significantly, to -0.92 tCO2e/t.


Including Module D in embodied carbon calculations is essential if benchmarking steel’s carbon footprint against its construction counterparts. While concrete and timber can appear more efficient at Module A, they are outweighed by the long-lasting benefits of steel at Module D.


The BCSA recommends using these figures to gauge embodied carbon for projects when the source of the structural steel is not yet known. The BCSA updates its calculations periodically, to reflect changes in the market.


However, while these figures are helpful to benchmark forecast emissions and as a start point for projects, complete LCAs are the only way to get an accurate calculation on an individual project’s impact.


To ensure comprehensive LCAs, engaging contractors to source the relevant information and share expertise is key.


Limiting embodied carbon


Steelworkers can play an important role in limiting emissions, since the core structure’s materials can represent up to 80% of a construction’s embodied carbon. By considering the materials used and their method of assembly to suit design and reuse later, they can work closely with designers and architects to design efficient structures.


For example, new steel frames can be designed using members and components able to be dismantled and recycled, or able to be easily adapted or modified to accommodate changing usage. This involves using standardization and repetition in member design, and connection design that limits or entirely negates welding. It can also include employing cellular beams to accommodate building services and flexibility.


For existing frames, steelworkers can be central to the feasibility of modifying buildings or bringing properties back into use – negating the need for entirely new structures.


Delivering sustainable construction


To effectively reduce embodied carbon, both on current projects and future works, employing the expertise and skills of specialist subcontractors is key.


Talk to us today for guidance and advice on your projects.

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