Explainer: Low-carbon materials (cement, steel, timber) — what sustainability teams need to know

Why It Matters

Cement, steel and timber together account for roughly 15 percent of global greenhouse-gas emissions, with cement production alone responsible for approximately 8 percent and steel for another 7 percent (IEA, 2025). As operational energy in buildings falls thanks to tighter envelope standards and heat-pump adoption, embodied carbon in structural materials now represents the dominant share of a new building's lifecycle footprint. The Global Alliance for Buildings and Construction estimates that embodied carbon will constitute more than half of cumulative building-sector emissions between now and 2050 (GlobalABC, 2025). Procurement teams that ignore material choices risk locking in decades of carbon liability. Conversely, organisations that shift to low-carbon alternatives can cut embodied emissions by 40 to 80 percent per project while positioning themselves ahead of tightening regulation. The EU Carbon Border Adjustment Mechanism (CBAM), which entered its transitional phase in 2023 and will impose full financial obligations from 2026, makes this a commercial as well as environmental imperative (European Commission, 2025). Understanding the technology landscape, cost dynamics and evaluation criteria for low-carbon cement, steel and timber is now essential knowledge for any sustainability team operating in the built environment.

Key Concepts

Embodied carbon refers to the total greenhouse-gas emissions associated with extracting, manufacturing, transporting and installing building materials. It is measured in kilograms of CO₂-equivalent per unit of material (kgCO₂e/tonne or kgCO₂e/m³) and disclosed through Environmental Product Declarations (EPDs). Unlike operational carbon, which can be reduced through retrofits, embodied carbon is fixed at the point of construction.

Environmental Product Declarations (EPDs) are standardised, third-party-verified documents that quantify a product's environmental impact across its lifecycle. EPDs follow ISO 14025 and EN 15804 standards and are the primary tool for comparing the carbon intensity of competing materials. The EC3 database maintained by Building Transparency now contains over 150,000 EPDs, making product-level benchmarking feasible at scale (Building Transparency, 2025).

Green premiums describe the additional cost of a low-carbon material relative to its conventional counterpart. For cement and steel, green premiums have been narrowing: BloombergNEF reported in 2025 that the green premium for low-carbon steel produced via hydrogen-based direct reduced iron (H2-DRI) fell to 20 to 35 percent above conventional blast-furnace steel, down from 40 to 50 percent in 2023 (BloombergNEF, 2025). For mass timber, cost parity with concrete-frame construction has already been achieved in mid-rise buildings in several North American and European markets.

Supplementary cementitious materials (SCMs) are industrial byproducts or natural pozzolans that partially replace Portland cement clinker, reducing the CO₂ intensity of concrete. Ground granulated blast-furnace slag, fly ash, calcined clay and limestone are the most common SCMs. LC3 (Limestone Calcined Clay Cement) can reduce clinker content by up to 50 percent and cut cement emissions by 30 to 40 percent using widely available raw materials (EPFL, 2024).

Mass timber encompasses engineered wood products such as cross-laminated timber (CLT), glue-laminated timber (glulam) and nail-laminated timber (NLT). These products sequester carbon during the growth phase of the source trees and, when sourced from sustainably managed forests, offer a biogenic carbon benefit that can offset a significant share of manufacturing emissions. A typical CLT element stores roughly 700 kgCO₂e per cubic metre of wood (Churkina et al., 2020).

How It Works

Low-carbon cement and concrete pathways fall into four categories. First, clinker substitution through SCMs reduces the most carbon-intensive step of cement production. Second, carbon capture, utilisation and storage (CCUS) fitted to cement kilns can abate 90 percent or more of process emissions; Heidelberg Materials' Brevik CCS project in Norway, scheduled for full operation in 2025, will capture 400,000 tonnes of CO₂ annually (Heidelberg Materials, 2025). Third, novel binder chemistries such as Solidia's CO₂-cured concrete and CarbonCure's injection technology mineralise CO₂ directly into the concrete mix. CarbonCure has been used in over 850 concrete plants worldwide, saving approximately 400,000 tonnes of CO₂ to date (CarbonCure, 2025). Fourth, performance-based mix design optimises aggregate gradation, admixtures and water-to-cement ratios to cut cement content by 20 to 30 percent without compromising structural performance.

Green steel production centres on two approaches. The primary route replaces coal-fired blast furnaces with hydrogen-based direct reduction of iron ore (H2-DRI) followed by electric arc furnace (EAF) melting powered by renewable electricity. SSAB's HYBRIT project in Sweden delivered the world's first fossil-free steel to Volvo in 2021 and is scaling toward commercial production of 1.3 million tonnes per year by 2026 (SSAB, 2025). The secondary route maximises scrap-based EAF steelmaking, which already accounts for roughly 30 percent of global production and emits 0.4 tonnes of CO₂ per tonne of steel compared with 1.8 to 2.2 tonnes for the blast-furnace route (World Steel Association, 2025). ArcelorMittal is investing in both paths, with its XCarb recycled and renewably produced steel achieving emissions reductions of up to 70 percent.

Mass timber construction uses prefabricated engineered wood panels and beams to replace concrete and steel in structural applications for buildings up to 18 storeys or more. Stora Enso and Mercer International supply CLT and glulam from FSC-certified forests. The Ascent tower in Milwaukee, completed in 2022 at 25 storeys, demonstrated that mass timber can meet fire-safety, acoustic and seismic requirements while reducing embodied carbon by approximately 60 percent compared with a concrete equivalent (Thornton Tomasetti, 2023). Bamboo-based engineered products are also emerging as viable alternatives in tropical regions, with companies like MOSO International producing structural-grade bamboo panels.

What's Working

Regulatory momentum is accelerating adoption. As of early 2026, over 30 jurisdictions have enacted or proposed whole-life carbon limits for buildings. The EU's revised Energy Performance of Buildings Directive (EPBD) requires lifecycle carbon assessments for all new buildings from 2028 and sets maximum embodied-carbon thresholds from 2030 (European Parliament, 2024). In the United States, the federal Buy Clean Act now mandates EPDs and maximum carbon-intensity thresholds for steel, concrete, glass and asphalt used in federally funded projects (White House, 2025). California's Buy Clean California Act, the earliest state-level policy, has already shifted procurement toward lower-carbon structural steel.

Procurement innovation is lowering barriers. The First Movers Coalition, convened by the World Economic Forum and the US State Department, has secured near-term purchase commitments from over 100 companies representing more than 12 percent of global GDP. Coalition members including Holcim, Volvo and Salesforce have pledged to source at least 10 percent of their steel and cement from near-zero-emission producers by 2030 (First Movers Coalition, 2025). SteelZero, led by the Climate Group, now has over 50 member companies committing to 100 percent net-zero steel by 2050.

Cost competitiveness is improving. Mass timber mid-rise buildings have achieved cost parity with concrete in markets including the Pacific Northwest, Scandinavia and Austria. Low-carbon concrete using SCMs and optimised mix designs often costs no more than conventional concrete and can reduce material quantities by 15 to 25 percent. Even for green steel, falling renewable electricity prices and rising carbon prices in the EU Emissions Trading System (which exceeded EUR 65 per tonne in 2025) are narrowing the economic gap.

What Isn't Working

Supply-chain readiness remains a bottleneck. H2-DRI steel plants require dedicated green hydrogen infrastructure that is still under construction across most regions. Global green hydrogen electrolyser capacity reached only 2.1 GW by end of 2025, far short of the roughly 90 GW needed for steel decarbonisation alone by 2030 (Hydrogen Council, 2025). Cement CCUS projects face high capital costs of $60 to $120 per tonne of CO₂ captured and lack the transport and storage infrastructure needed at scale.

Data gaps undermine procurement decisions. While EPD availability has expanded rapidly, product-level data quality varies. Industry-average EPDs, which account for over 60 percent of entries in most databases, can overstate or understate emissions by 30 percent or more compared with facility-specific declarations. Harmonisation across national EPD programmes remains incomplete, complicating cross-border comparisons.

Building codes lag behind technology. Many jurisdictions still prescribe material types rather than performance outcomes, effectively excluding mass timber and novel binder systems from structural applications. Height limits for timber buildings vary from 4 storeys in some Asian markets to 18 or more in parts of Europe, creating fragmented market access. Insurance underwriters remain cautious about mass timber fire performance despite successful full-scale fire tests.

Greenwashing risk is real. Terms like "green steel" and "low-carbon concrete" lack universally agreed definitions. Without standardised thresholds, producers can claim low-carbon status based on marginal improvements. The ResponsibleSteel certification and the Global Cement and Concrete Association's (GCCA) 2050 roadmap provide frameworks, but adoption is uneven.

Key Players

Established Leaders

• Holcim — World's largest cement producer, targeting 20 percent CO₂ reduction per tonne of cementitious material by 2025 through SCMs, CCUS and circular aggregates.
• Heidelberg Materials — Operating the world's first full-scale cement CCUS plant at Brevik, Norway, capturing 400,000 tCO₂/year.
• SSAB — Pioneer of fossil-free steel via the HYBRIT H2-DRI process, scaling to commercial production by 2026.
• ArcelorMittal — Investing over EUR 10 billion in decarbonisation through XCarb initiatives, combining DRI, scrap-based EAF and smart carbon pathways.
• Stora Enso — Europe's largest CLT manufacturer, supplying FSC-certified mass timber for buildings up to 18 storeys.

Emerging Startups

• CarbonCure — CO₂ mineralisation technology deployed in over 850 concrete plants globally, saving approximately 400,000 tCO₂.
• Solidia Technologies — CO₂-cured cement and concrete that reduces emissions by up to 70 percent versus conventional Portland cement.
• H2 Green Steel — Building Europe's largest green steel plant in Boden, Sweden, targeting 2.5 million tonnes per year by 2026.
• Brimstone — Producing carbon-negative Portland cement from calcium silicate rock instead of limestone, eliminating process CO₂.
• Prometheus Materials — Biologically grown building materials using microalgae to replace Portland cement.

Key Investors and Funders

• Breakthrough Energy Ventures — Backing Brimstone, CarbonCure and other materials innovators.
• First Movers Coalition — Demand-side commitments from 100+ companies for near-zero materials.
• Climate Group (SteelZero) — Corporate alliance driving demand for net-zero steel with 50+ members.
• European Investment Bank — Financing cement CCUS and green steel infrastructure projects across Europe.

Sector-Specific KPI Benchmarks

Action Checklist

• Establish an embodied carbon budget for every project and track it from concept design through completion using tools such as EC3, One Click LCA or Tally.
• Require facility-specific EPDs in procurement specifications rather than accepting industry-average declarations.
• Set maximum carbon-intensity thresholds for cement (below 400 kgCO₂/t) and steel (below 1.0 tCO₂/t) aligned with SBTi sectoral pathways.
• Pilot mass timber in at least one mid-rise project to build internal expertise and benchmark cost, schedule and carbon outcomes.
• Join demand-signal coalitions such as SteelZero, ConcreteZero and the First Movers Coalition to aggregate purchasing power and send clear market signals.
• Engage suppliers early in design to identify SCM availability, scrap-steel sourcing opportunities and regional timber supply from certified forests.
• Monitor regulatory timelines for the EU CBAM, EPBD lifecycle requirements and the US Buy Clean Act to ensure procurement aligns with upcoming mandates.
• Invest in workforce training on reading EPDs, performing lifecycle assessments and specifying low-carbon alternatives.

FAQ

What is the biggest barrier to adopting low-carbon materials? For cement and steel, the primary barriers are the cost premium of breakthrough technologies (CCUS, H2-DRI) and the lack of green hydrogen and CO₂ transport infrastructure at scale. For mass timber, regulatory restrictions on building height and lingering concerns about fire performance remain key constraints, although both are being addressed through updated building codes and successful demonstration projects. Across all three materials, insufficient availability of facility-specific EPDs complicates procurement decisions.

How do I compare materials using EPDs? EPDs quantify environmental impacts across standardised lifecycle stages (A1-A3 for cradle-to-gate, A1-A5 for cradle-to-site, and stages B and C for use and end-of-life). To compare products, ensure you are using the same functional unit (e.g., one cubic metre of concrete at a specified strength class), the same lifecycle stages, and EPDs generated under the same programme operator or at least the same EN 15804 standard version. The EC3 tool automatically normalises these variables for side-by-side comparison across over 150,000 products.

Is mass timber safe in fires? Engineered mass timber chars at a predictable rate of approximately 0.7 mm per minute, forming an insulating layer that protects the structural core. Full-scale fire tests conducted by the National Research Council Canada, the Bureau of Alcohol, Tobacco, Firearms and Explosives in the United States and Bre Global in the United Kingdom have demonstrated that properly designed CLT buildings can achieve the same or better fire-resistance ratings as concrete and steel structures. Insurance markets are gradually adjusting, with several major underwriters now offering standard terms for mass timber buildings up to 12 storeys.

Will carbon border taxes make low-carbon materials cheaper than conventional ones? The EU CBAM will progressively impose the EU ETS carbon price on imported cement, steel, aluminium and other materials from 2026. At current ETS prices above EUR 65 per tonne of CO₂, this adds roughly EUR 40 to 140 per tonne to conventional imported steel depending on production route. As free allowances phase out by 2034, domestic producers using low-carbon processes will gain a structural cost advantage. Similar mechanisms are under discussion in the United Kingdom and Canada.

What certifications should I look for when procuring green steel? ResponsibleSteel is the most comprehensive certification, covering greenhouse-gas emissions, water stewardship, biodiversity, human rights and community engagement at the site level. For product-level carbon intensity, look for facility-specific EPDs and verify claims against the Science Based Targets initiative's steel sector pathway, which calls for emissions below 1.1 tCO₂ per tonne of crude steel by 2030.

Sources

• IEA. (2025). Tracking Industry 2025: Cement and Steel. International Energy Agency.
• GlobalABC. (2025). 2025 Global Status Report for Buildings and Construction. Global Alliance for Buildings and Construction / UNEP.
• European Commission. (2025). Carbon Border Adjustment Mechanism: Implementation Update. European Commission.
• BloombergNEF. (2025). Green Steel Cost Tracker: H2-DRI Premium Trends. BloombergNEF.
• Building Transparency. (2025). EC3 Database: EPD Coverage and Growth Report. Building Transparency.
• EPFL. (2024). LC3: Limestone Calcined Clay Cement — Global Deployment Update. Swiss Federal Institute of Technology Lausanne.
• Heidelberg Materials. (2025). Brevik CCS Project: Construction and Commissioning Update. Heidelberg Materials.
• CarbonCure. (2025). Impact Report: Global CO₂ Savings and Plant Deployments. CarbonCure Technologies.
• SSAB. (2025). HYBRIT: Scaling Fossil-Free Steelmaking. SSAB.
• World Steel Association. (2025). Steel Statistical Yearbook 2025. World Steel Association.
• First Movers Coalition. (2025). Annual Progress Report: Near-Zero Materials Commitments. World Economic Forum.
• Hydrogen Council. (2025). Hydrogen Insights 2025: Electrolyser Deployment Tracker. Hydrogen Council.
• European Parliament. (2024). Revised Energy Performance of Buildings Directive (EPBD). Official Journal of the European Union.
• White House. (2025). Buy Clean Task Force: Federal Procurement Standards Update. The White House.