Materials emission factor trends

External decarbonisation trends for materials activities — curated sources, uncertainty ranges, and pathway-ready projections.

• Global

  Purchasedgoodsandservicesmass Cement emission factor trends — Global

  The updated IEA forecast for the cement sector reinforces the existing narrative of global decarbonization in cementitious materials. The Net Zero Scenario projects the cement emission factor to fall from about 575.7 kg CO2e/t in 2020 to roughly 446 kg CO2e/t by 2030 and to about 219 kg CO2e/t by 2040, implying reductions of roughly 23% by 2030 and about 62% by 2040 relative to 2020 (IEA, 2023). This trajectory sits alongside GCCA’s observed long-run trend, which shows the emission factor declining from 711 to 580 kg CO2/t cementitious between 2000 and 2022, i.e., an ~18% improvement over that period and evidence of ongoing global decarbonization in cementitious supply (GCCA, 2023). Taken together, the data point to accelerated decarbonization across regions and markets in the coming decade, consistent with broader policy, market, and technology shifts in the sector. Three primary dynamics are underpinning the observed trend and are likely to shape the next decade’s pace of reduction: - Blended cements with higher supplementary cementitious material (SCM) content are rising globally, lowering clinker demand and the associated process emissions per tonne of cementitious material (GCCA, 2023). The shift toward fly ash, slag, and natural pozzolans reduces emissions intensity while preserving performance. - Expanded use of alternative fuels in cement kilns is being tapped to improve energy security and waste-management outcomes, cutting fuel-related emissions and supporting lower overall emission intensity (IEA, 2023; GCCA, 2023). - Plant-level efficiency gains, including advanced preheater/calciner configurations and waste heat recovery, are complemented by emerging carbon capture, utilization, and storage (CCUS) pilots in cement plants, further reducing energy intensity and process emissions (IEA, 2023; GCCA, 2023). Policy and market context are reinforcing these drivers. Rising carbon prices and decarbonization mandates in major markets—coupled with explicit targets for low-carbon cement and clinker pathways—are incentivizing faster uptake of SCMs, alternative fuels, and energy-efficiency measures (IEA, 2023; European Commission, 2023). The convergence of policy signals, market adaptations, and technological progress suggests that the cement emission factor for purchased goods and services mass will continue to move lower across geographies and sectors, extending the downward trajectory documented by GCCA and projected by the IEA into the 2030s and 2040s.

• Global

  Purchasedgoodsandservicesmass Concrete emission factor trends — Global

  Historically the concrete industry has been a major emitter of CO2, but the emission factor has reduced from 252.9 to 234.1 kg CO2 / m3 between 2019 and 2024 according to the ICE Database v3. The 2024 forecast from the IEA's Net Zero Scenario projects further decarbonization of cement (which accounts for the majority of concrete emissions), reducing the factor to roughly 205 kg CO2e/m3 by 2030, about 162 kg by 2035, and about 119 kg by 2040, assuming cement represents ~85% of concrete emissions by weight (IEA Net Zero Scenario; Update trigger). This trajectory aligns with policy and market drivers: the EU’s Carbon Border Adjustment Mechanism and rising EU ETS carbon prices are accelerating shifts toward lower-emission cement and the use of supplementary cementitious materials and blended cements, reinforcing the decarbonization pathway described by the IEA (European Commission CBAM; IEA Net Zero Scenario).

• Global

  Purchasedgoodsandservicesmass Steel emission factor trends — Global

  Global, embodied emissions in purchased steel goods have eased modestly as buyers and producers continue decarbonizing supply chains. According to the IEA, the steel-related emission factor in purchased goods and services fell roughly 3–4% across 2010–2022, a trend driven by more recycled steel, greater use of electric-arc furnaces (EAF), efficiency gains in steel production, and the decarbonization of electricity grids in key markets—all underpinned by policy levers such as carbon pricing and low-carbon procurement standards. For global purchasers, these shifts translate into lower cradle-to-gate emissions for steel-intensive inputs and clearer opportunities to curb scope 3 emissions by preferentially selecting low-emission suppliers and materials. The 2022–2030 outlook for construction materials reinforces this trajectory: the IEA’s Net Zero Scenario forecasts a substantial reduction in cement emission factors (from 1.41 in 2022 to 1.07 by 2030, and around 0.439 by 2040), signaling stronger decarbonization momentum across energy-intensive inputs that, while targeting cement, mirrors the broader policy and market direction shaping steel procurement (IEA Net Zero Scenario). These dynamics are consistent with the ongoing shift in steel supply chains toward lower-emission inputs as procurement criteria tighten and market incentives align with decarbonization. Driving factors include: broader adoption of scrap-based steel production and higher EAF participation, supported by recycling infrastructure and policies (World Steel Association); continuing decarbonization of electricity generation that reduces energy-intensity in steelmaking (IEA Electricity Market Report); and policy instruments such as carbon pricing and low-carbon procurement standards that reward low-emission steel supply (IEA framing and European procurement frameworks, e.g., Green Public Procurement criteria). In addition, pilot and demonstration efforts in low-emission steelmaking—such as hydrogen-based direct reduction projects—signal feasible pathways for deeper decarbonization in the medium term (HYBRIT consortium).

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