Getting more from every tonne of steel

Standard design practices often use roughly 20–50 per cent more structural steel than is strictly necessary. That gap represents a significant opportunity to cut steel’s carbon footprint.

Steel is in our buildings, bridges, water networks, transport systems and renewable energy infrastructure. Around 52 per cent of all steel globally goes into buildings and infrastructure. Reducing the greenhouse gas emissions associated with steel is therefore both a pressing challenge and one that extends well beyond the steel industry itself.

In April, the Sustainable Steel Council released Forging Ahead, a plan for net-zero greenhouse gas emissions from steel used in New Zealand buildings and infrastructure. It sets a pathway to reduce direct and electricity-related emissions by more than 30 per cent by 2030 and more than 90 per cent by 2050, compared with a 2020 baseline.

Those reductions are significant because our modelling assumes New Zealand’s population will grow by around 31 per cent, from 5.1 million in 2020 to approximately 6.7 million by 2050, with steel demand rising proportionately if there is no intervention. The plan therefore does not depend on reduced economic activity. It requires us to lower emissions per tonne of steel and reduce unnecessary material demand.

There are five main strategies: extending the life of existing assets through adaptive reuse, using steel more efficiently through better design and construction, decarbonising electricity and hydrogen supply, expanding scrap-based electric arc furnace production and reducing emissions from ironmaking.

For those involved in infrastructure delivery, some of the earliest and most accessible opportunities lie in the first two.

Start with design

Optimising structural design can reduce the amount of steel required without compromising safety or performance. Getting there requires decisions to be made early. Early peer review, digital modelling and better coordination between designers and contractors can all reduce routine over-specification – including the additional material that can result from standard safety factors and simplifying the range of structural members sent to site.

The opportunity continues through fabrication and construction, where greater efficiency can further reduce material use and waste. By 2050, our modelling assumes a 20 per cent reduction in steel use in new construction through better design. That is a substantial contribution to the overall emissions reduction path.

This also changes how we should think about embodied carbon during project development. Greenhouse gas emissions need to become a standard consideration in early design, alongside cost, quality and timeline – not an afterthought applied once the structural system is already set.

Procurement then has a critical role in ensuring those design intentions survive from drawing board to completed asset. Our plan envisages procurement contracts incorporating upper limits for embodied carbon by material type, supported by industry benchmarks. It also identifies the need for mechanisms to verify specified low-emissions materials have not been value engineered out during construction.

Better digital workflows between design and construction can help here too, enabling products to be specified precisely rather than relying on generic, off-the-shelf materials.

Keep steel working for longer

There is another way to reduce demand for new steel: get more life from the steel we already have.

Adaptive reuse means extending the life of buildings and infrastructure rather than automatically demolishing and replacing them. It can include repurposing existing structures, upgrading assets instead of replacing them and designing new assets so they can themselves be adapted in the future. Our modelling assumes this approach can reduce steel demand by 10 per cent by 2050.

Steel is well suited to this. Approximately 85 per cent of steel in New Zealand is recovered for reuse or recycling at the end of its current life. Steel can be reused directly and recycled repeatedly without loss of quality, which means the end of an asset’s current use is best understood as the beginning of another material life cycle.

That has practical implications for how assets are designed and documented. Digital material passports is one of the tools that can help. Better records of what has gone into a building or structure allow it to function as a material bank. When its original use ends, steel sections can be identified, recovered and reused, while high-quality scrap can be recycled into new steel.

Many of the benefits of decisions made today will be realised beyond 2050. Buildings being constructed now are likely still to be standing then, which makes designing for disassembly and reuse a long-term but necessary part of the picture.

Alongside these changes in demand, the steel supply chain is changing too.

A changing supply chain

Our plan identifies greater recycling of steel scrap as its single most important short-term strategy. Recovered steel should be treated as a strategic resource – one that needs efficient collection, sorting, domestic processing and recycling rather than export.

Electric arc furnaces can melt steel scrap into new steel using electricity and, when powered by renewables, achieve emissions around 80 per cent lower than conventional coal-based blast furnace production. This shift is already under way in New Zealand. A new electric arc furnace is now operating at Glenbrook, backed by around $300 million of co-investment from BlueScope Steel and the New Zealand Government. From late 2026 it is expected to cut national greenhouse gas emissions by around one million tonnes a year – more than 1 per cent of the country’s gross emissions, and the largest single-site emissions reduction initiative in New Zealand to date.

For logistics, infrastructure and procurement professionals, Forging Ahead has implications well beyond decisions about which steel product to specify.

Before replacing an asset, ask whether it can be retained or adapted. Bring designers and engineers together early to reduce material use, and make sure those decisions are captured in procurement contracts that hold through to construction. Invest in better records of what goes into assets so steel can eventually be identified, recovered and returned to productive use.

And treat recovered steel as a logistics challenge as much as a materials one – it needs to be collected, sorted, moved and processed efficiently to realise its value.

The steel industry has set a target of more than 90 per cent reduction in direct and electricity-related emissions by 2050, without relying on carbon offsets. Reaching it will require action across the entire value chain – from manufacturers and importers to designers, engineers, builders, recyclers, asset owners, government and those responsible for the infrastructure and logistics systems that connect them.

The projects being delivered today are part of that process. The choices made now – about what to build, how to specify it and what happens to it at the end – will determine how quickly the industry gets there.

Jeremy Sole is the Executive Officer for the Sustainable Steel Council (SSC), the leading industry body for sustainability in New Zealand’s steel sector. He spearheaded the development of SSC’s Green Building Council recognised Responsible Products Certification.