Low Embodied Carbon Steel

What is low embodied carbon steel? Why is it a necessary step in modern construction thinking? How does voestalpine Metsec strive to push the industry forward towards the Net Zero deadline? Here we delve into what exactly this term refers to and what the industry as a whole needs to be doing about it.

The construction industry is where innovation, development and long-term thinking thrive. At voestalpine Metsec, sustainability is not just a buzzword, but a practical, important part of steel production.

The primary focus for designers has been operational carbon reduction, economising on the use of energy, and water, and streamlining the maintenance of buildings throughout their lifecycle.

The success of this approach has led designers and policymakers to focus on the embodied carbon of the manufacturing process.

What is Embodied Carbon?

Embodied carbon is a calculation of the CO2 released during the manufacture, delivery and construction process throughout the entire lifecycle of a building.

The embodied carbon calculation includes the production of raw materials, and their processing into constructible elements, including fixtures and fittings. The transport and construction of the building, and the demolition of it at the end of its lifecycle all account for the carbon budget.

How Big is the Carbon Footprint of Steel?

The carbon footprint of traditional, oxygen blast furnace-produced steel, is second only to the production of concrete, which makes it a prime contender for reduction strategies. Furnaces that process virgin ore have an average carbon cost of up to 2000 kgCO₂e/tonne.

The steel production industry is in the process of upgrading from basic oxygen furnaces to electric arc furnaces powered by renewable energy sources. In time, this should transform the carbon budget and reduce the cost to approx. 800 kg/tonne.

Whole-life carbon assessments

The UK Government has recognised that there are achievable targets for carbon reduction in construction, and whole-life carbon assessments (WLCAs) are an important tool in measuring progress. At voestalpine Metsec, steps are already underway to reduce the carbon footprint of steel used in cold-formed manufacturing.

The main measure manufacturers scrutinise is cradle-to-gate, the carbon cost of taking steel from raw ore to delivering a finished product to a construction site. Since 2011, the City Council of Brighton and Hove in the UK has stipulated cradle-to-gate assessments at the planning stage of any development.

Designers, however, are increasingly required to determine the cradle-to-cradle whole-life cost of all parts of a building. As demands for a more circular economy increase, the recyclability of a planned building also comes into focus.

What is Low Embodied Carbon Steel?

Low embodied carbon steel is material that has been manufactured using modern, greener technologies, or steel that has been sourced from recycling plants.

While 98% of steel used in construction is recyclable, current global rates of recycling mean that just 40% of steel is available for reuse.

European numbers are currently (as of September 2024) better, with British Steel reporting the availability of 56% recycled steel across the sector. 32% is classed as pre-consumer scrap; metal that is recycled at the factory or furnace. The remainder is post-consumer recycling that comes via reclamation and demolition.

Industry focus on cleaner means of production, reducing transport emissions, and managing out the over-specification of products during the design process, are all key to achieving low embodied carbon steel.

The calculation for low embodied carbon steel accounts for energy use in suppliers’ offices as well as factory production.

‘Moving our electricity requirements to 100% renewable sources has resulted in a 67% reduction in our carbon footprint and by the end of this Summer (2024) we will have installed enough solar PV panels to generate 48% of our total electricity requirements.’ – Andy Hackett.

Metsec Decarb: Mass balance, carbon credits and offsetting

At voestalpine Metsec, steel from our suppliers is produced using electric arc furnaces powered by renewable energy to create reduced carbon steel; Metsec Decarb. It delivers direct carbon reduction and does not rely on creative data or other processes to achieve a sustainable target.

• Mass balance is a catch-all term that describes off-setting high-carbon production methods with savings, or the purchase of carbon credits, to bring the final carbon cost down. Tracking emissions right across the supply chain is essential to offset the impact of an oxygen blast furnace.
• Carbon credits, where a company invests in reforestation or other green energy initiatives, may balance their production of carbon on paper but do nothing to advance the reduction of their own emissions.
• Carbon offsetting is not a sustainable practice in the longer term as Government, and client expectations of green solutions become ever more stringent.

Reducing Carbon Lifecycle Footprints

The carbon lifecycle footprint of a building is defined mainly by the costs of its operation throughout the design lifetime and occupation by end users.

Operational considerations that have a direct carbon cost are:

Operational carbon costs

Different buildings have different operational costs. Supermarkets have a very high use-to-material ratio, considering that these buildings are often lit, and heated for 24 hours a day, while structurally, they are light on materials.

Domestic structures, apartment buildings and individual houses have lower operational costs, however, the ratio remains at a level that can still benefit from carbon reduction at the manufacturing and construction stage.

Warehouses have the lowest overall use-to-material ratio as they are not required to support human habitation.

Water consumption

According to a past UK Government report, domestic water consumption once accounted for some 89% of operational carbon emissions in the built environment, associated mostly with the energy required to heat water.

Since then metering and other demand management strategies, such as water reduction devices and efficient water use appliances have had a positive impact on reducing CO2 emissions.

Maintain, repair, replace and refurbish; the 6Rs

The 6Rs are a powerful way to think about any construction design: Reduce, Rethink, Reuse, Recycle, Repair, Refuse.

• Reduce: Can you use fewer materials? Does the product require less packaging, transport, or energy to manufacture?
• Rethink: Is it required? What is its recyclability? Can you increase its longevity?
• Reuse: Can it be easily dismantled? Can it be repurposed?
• Recycle: Can the product be made with recycled materials? Is it easy to recycle at the end of its working life?
• Repair: Can the product, and/or its parts be repaired or replaced cheaply without resorting to entire replacement?
• Refuse: Is it practical to refuse to use non-recycled materials? Can you refuse to design any element that cannot be recycled?

Embodied Carbon in the Built Environment

Assessing the impact of carbon emissions in the built environment promotes long-term thinking. Consideration of how a structure may be disassembled and reconstituted into components or raw materials will become an essential part of how industry designs for construction in the future.

When used for Metsec Framing and Purlins products, Metsec Decarb achieves a reduction in CO2 emissions of 54.7%, whilst in Metsec Dry Lining products the reduction is 65.35%. In each case, Metsec Decarb contains less than half the amount of carbon dioxide per tonne for the same quality of steel.’ – Andy Hackett.

Environmental Product Declarations

Metsec can supply a selection of EPDs (Environmental Product Declarations) for submission at the proposal stage. Metsec EPDs (viewable here) have been submitted to the BECD (Built Environment Carbon Database) whole-life carbon assessments of built assets database, to help create a foundation for regulation and standardisation.

BIM and the Art of Carbon Reduction

voestalpine Metsec is the first Tier 2 cold-roll steel manufacturing company in the UK to be awarded BIM Level 2 Certification by the BSI. Using BIM (Building Information Modelling) the design team can quantify, almost to the kg the amount of steel required.

Excess materials and superfluous details can be identified and mitigated at the design and planning stage, thereby lowering the final embodied carbon budget.

BIM offers a way to integrate and interrogate construction design to improve compatibility with the 6Rs, by reducing components, not to a bare minimum, but to an elegant, sustainable solution.

Net Zero and Low Carbon Steel Production

The UK Government is committed to achieving net zero carbon emissions by 2050, and at the recent COP26, the UN Climate Change Conference, the UK targeted a 68% reduction by 2030.

Decarbonizing steel production, from cradle to cradle requires a holistic approach to design and delivery. Up to 7% of greenhouse gases produced annually can be traced and allocated to the steel industry.

‘voestalpine Metsec remains committed to achieving net zero carbon emissions by 2035, investing in new systems and equipment to reduce carbon emissions throughout its operations.’ – Andy Hackett.