Emission factor trends

External trends describe how emission factors (for example grid electricity intensity) are expected to change over time. Each page summarises authoritative sources, a min–max range, and the Viable Pathway mid projection used in our tool.

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• Business travel · Global · km

  Businesstravel Air Internationalbusiness emission factor trends — Global

  International air travel emission factors for businesstravel_air_internationalbusiness have historically fluctuated around the 0.39–0.41 kg CO2e per passenger-km range, with pandemic-related disruptions contributing to short-term volatility (DESNZ, 2024). The ICCT’s Aviation Vision 2050 update, issued in September 2025, shows a notably stronger decarbonization path under the GHG Forward scenario: aviation warming intensity is projected to decline from 0.118 mC in 2025 to 0.089 mC by 2050, a reduction of roughly 25%—signaling meaningful efficiency and fuel-shift progress even as demand for international travel grows (ICCT, 2025). This trajectory reflects a confluence of policy, market, and infrastructure dynamics that collectively dampen emissions intensity while sustaining growth in travel. Key drivers include accelerated SAF deployment and uptake supported by regulatory and fiscal measures: the EU ReFuelEU Aviation blending mandates, the UK Jet Zero strategy, and US SAF incentives under the Inflation Reduction Act collectively improve SAF economics and market uptake (European Commission, 2023; UK Government, 2022; IRS, 2022). In parallel, continued fleet modernization and engine-efficiency improvements, together with optimized routing and higher-capacity aircraft, reduce fuel burn per passenger-km (IATA, 2023). International coordination through ICAO’s CORSIA further reinforces efficiency gains and SAF adoption where feasible (ICAO, 2023). However, SAF supply constraints and higher costs remain potential constraints that could temper the pace of decarbonization, even as policy momentum and technological advances support a durable downward trend in emissions intensity (IATA, 2023).

  Updated 2025-10-03

• Business travel · Global · km

  Businesstravel Air Internationaleconomy emission factor trends — Global

  International business travel by air in economy class (businesstravel_air_internationaleconomy) sits within a sector where emissions intensity per passenger-kilometre is shaped by aircraft efficiency, load factors, and route mix. The ICCT’s Aviation Vision 2050 (Sept 2025) projects that, under the Current Commitments scenario, the warming impact attributable to aviation per unit of travel is expected to fall from 0.118 mC in 2025 to 0.107 mC in 2050, signaling a decarbonization trajectory that increasingly decouples growth in international travel from emissions—provided technology progress and policy commitments continue (ICCT, 2025). This aligns with broader assessments that aviation remains a relatively small share of global CO2 but that substantial emissions reductions are achievable through sustained efficiency gains, sustainable aviation fuels (SAF), and policy measures (IEA, 2023; ICCT, 2025). Driving factors behind the projected trend include: (1) accelerated SAF deployment supported by regulatory mandates and incentives—such as the EU ReFuelEU Aviation framework and U.S. SAF incentives—which reduce the carbon intensity of jet fuel used in international operations (European Commission, 2023; IATA, 2024); (2) continued fleet renewal with next-generation, more fuel-efficient aircraft that lower fuel burn per passenger-kilometre (ICAO, 2023); and (3) improvements in air traffic management and route optimization (e.g., SESAR/NextGen initiatives) that shorten flight distances and reduce unnecessary holds, further trimming fuel use (Eurocontrol, 2023). Collectively, these dynamics support a downward trajectory in the economy-class international emission factor even as activity recovers, with policy-backed decarbonization pathways forecasting a gradual reduction in the sector’s warming impact through 2050 (ICCT, 2025; ICAO CORSIA).

  Updated 2025-10-03

• Business travel · Global · km

  Businesstravel Air Internationalfirst emission factor trends — Global

  The UK’s business travel footprint shows that international first‑class air travel remains a small but highly emissions‑intensive portion of travel-related emissions. The 2016–2024 trend for the international first‑class flight emission factor moves from about 0.548 to a high near 0.562 in 2021–2022, before easing to around 0.539 in 2023–2024, indicating that fleet efficiency gains and shifts in premium travel demand have partially offset growth in emissions. BEIS/DEFRA’s GHG Conversion Factors for Company Reporting state that “emissions from air travel are calculated from fuel burn and occupancy and vary by seating class” (BEIS/DEFRA, GHG Conversion Factors for Company Reporting, 2024). ICAO also notes that “improvements in aircraft efficiency have not fully offset rising demand for international aviation” (ICAO, 2023). In the UK context, this trend is relevant across all regions and aligns with policy aims to decarbonise aviation while allowing necessary business mobility.

  Updated 2025-10-03

• Business travel · Global · km

  Businesstravel Air Internationalpremiumeconomy emission factor trends — Global

  Global flight emission factors continue to decline, driven by newer aircraft, growing SAF use, and policies that price carbon or mandate cleaner fuels. The ICCT’s Aviation Vision 2050 (Sept 2025) projects international premium-class warming impacts falling from 0.118 mC in 2025 to 0.089 mC by 2050—a roughly 25% drop in intensity. This is consistent with trends from 2016–2024, where efficiency gains and early SAF uptake lowered emission factors even as demand increased (IATA; IEA; ICAO). Policy frameworks—including CORSIA and national or regional SAF strategies such as the UK Jet Zero Strategy and EU ReFuel Aviation—reinforce this downward pressure. Three main drivers underpin the trend: (1) SAF scale-up supported by mandates and market-based measures, which cut life-cycle emissions for long-haul international aviation; (2) continued fleet modernization and propulsion improvements that reduce fuel burn per passenger-kilometre; and (3) operational and air-traffic efficiency gains that limit avoidable fuel use. Together, these dynamics point to continued, though increasingly policy- and SAF-dependent, reductions in the carbon intensity of international premium air travel.

  Updated 2025-10-03

• Business travel · Global · km

  Businesstravel Air Longhaulbusiness emission factor trends — Global

  Air travel emission factors for businesstravel_air_business have historically fluctuated around the 0.39–0.41 kg CO2e per passenger-km range, with pandemic-related disruptions contributing to short-term volatility (DESNZ, 2024). The ICCT’s Aviation Vision 2050 update, issued in September 2025, shows a notably stronger decarbonization path under the GHG Forward scenario: aviation warming intensity is projected to decline from 0.118 mC in 2025 to 0.089 mC by 2050, a reduction of roughly 25%—signaling meaningful efficiency and fuel-shift progress even as demand for international travel grows (ICCT, 2025). This trajectory reflects a confluence of policy, market, and infrastructure dynamics that collectively dampen emissions intensity while sustaining growth in travel. Key drivers include accelerated SAF deployment and uptake supported by regulatory and fiscal measures: the EU ReFuelEU Aviation blending mandates, the UK Jet Zero strategy, and US SAF incentives under the Inflation Reduction Act collectively improve SAF economics and market uptake (European Commission, 2023; UK Government, 2022; IRS, 2022). In parallel, continued fleet modernization and engine-efficiency improvements, together with optimized routing and higher-capacity aircraft, reduce fuel burn per passenger-km (IATA, 2023). International coordination through ICAO’s CORSIA further reinforces efficiency gains and SAF adoption where feasible (ICAO, 2023). However, SAF supply constraints and higher costs remain potential constraints that could temper the pace of decarbonization, even as policy momentum and technological advances support a durable downward trend in emissions intensity (IATA, 2023).

  Updated 2025-10-03

• Business travel · Global · km

  Businesstravel Taxi All emission factor trends — Global

  Across all regions, the emission factor for taxis has reduced over 2016–2024, with an overall roughly 9% reduction. This pattern mirrors broader shifts in business travel and taxi fleets: newer, more efficient engines, tighter urban emission rules, and greater use of cleaner fuels or hybrid configurations are replacing older, higher-emitting vehicles. According to DESNZ, this historic trend reflects steady efficiency gains and fleet renewal rather than short-term volatility. The trend is reinforced by global and national policy momentum toward lower transport emissions, including incentives for fleet modernization and the growing prevalence of low-emission zones; the ICCT notes that electrification and tighter standards are increasingly shaping taxi emissions, which supports the observed downward trajectory.

  Updated 2025-10-13

• Business travel · Global · km

  Businesstravel Vehiclerental Diesel emission factor trends — Global

  The UK DESNZ historic data released in 2024 show a consistent downward path in emission factors from 2015 to 2024, with the figures moving from 0.185363 down toward 0.16983 across the period. This pattern aligns with broader decarbonization efforts in road transport, where fleet renewal toward newer, more efficient diesel models and a gradual shift to low-emission fleets are reducing per-kilometre emissions. As the IEA notes, “the transport sector continues to decarbonize as efficiency improves and electrification expands,” which supports observed reductions in emission factors. The official UK framework also underpins these calculations: BEIS/Department for Energy Security and Net Zero and related conversion factors provide the benchmarks used for estimating emissions from organizational activities, with downward revisions reflecting technological gains and policy-driven fleet changes. In 2025, the downward trend is likely to persist as rental fleets increasingly favor efficiency and alternative propulsion options.

  Updated 2025-10-02

• Company vehicle · Australia · kWh

  Companyvehicle Hgv Bev emission factor trends — Australia

  Australia is committed to reducing GHG emissions to 43% below 2005 levels by 2030. A key contribution to this target is the expanded Capacity Investment Scheme to deliver on the government’s target to achieve 82% renewable electricity by 2030.

  Updated 2025-06-01

• Courier · Global · km

  Courier Land emission factor trends — Global

  "Across the global courier landscape, the courier_land emission factor for diesel delivery vans (up to 3.5 tonnes) per kilometre is showing a downward trend. UK Department for Energy Security and Net Zero historic data indicate the factor fell from about 0.2690 kg CO2e per km in 2015 to around 0.2316 kg CO2e per km in 2024, a decline of roughly 14%, reflecting fleet renewal with more efficient engines, improved route optimization, and broader decarbonisation policies in freight. As the IEA notes, 'improving energy efficiency and electrification of road freight are critical to reducing emissions per kilometre' (IEA, 2023), while UK DESNZ adds that 'emissions per kilometre are falling as fleets modernise and adopt cleaner technologies' (UK DESNZ, 2024). Given the all-geography scope, these UK trends suggest similar improvements may occur globally as fleets turnover and cleaner technologies proliferate."

  Updated 2025-10-02

• Freighting goods · Global · km

  Freightinggoods Road Hgvdiesel emission factor trends — Global

  Across all geographies, the road freight emission factor for heavy goods vehicles (diesel) per kilometre is shaped by engine efficiency, fleet turnover, and load factors. UK DESNZ BEIS historic data for HGV diesel show a trend from 2015 to 2024: 0.92797 (2015), 0.91484 (2016), 0.87029 (2017), 0.87287 (2018), 0.88025 (2019), 0.8654 (2020), 0.86407 (2021), 0.89061 (2022), 0.89061 (2023), 0.89061 (2024). In broad terms, this reflects early gains in efficiency from newer engines and drivetrain improvements, followed by a plateau as fleets mature and freight demand evolves. As the IEA notes, 'freight transport remains a significant challenge to decarbonize' (IEA, 2023), underscoring why per-kilometre emission factors can shift with technology adoption and policy changes.

  Updated 2025-10-02

• Freighting goods · Global · tonne.km

  Freightinggoods Sea Container emission factor trends — Global

  Globally, the emission factor for freightinggoods_sea_container in the freightinggoods category has moved only modestly from 2018 to 2024, effectively remaining flat with a tiny net decrease, a pattern noted by the UK Department for Energy Security and Net Zero (UK DESNZ, 2024). The 2025 forecast, however, signals a markedly different trajectory for all geographies as policy progress and market responses in international shipping mature. The International Maritime Organization (IMO) projects meaningful emissions reductions through 2030 and 2035 under its Direct Compliance Scenario, with reductions of about 21% by 2030 and 44% by 2035 relative to 2024 levels, indicating a shift from pure efficiency gains to price signals and fuel standards (IMO, 2025). This revised outlook rests on a trio of policy and market factors: (1) the IMO’s ongoing tightening of the policy framework, including drafting a mandatory global marine fuel standard and introducing GHG emissions pricing for shipping (IMO, 2025); (2) continued deployment of efficiency measures such as the Energy Efficiency Existing Ship Index (EEXI) and slow steaming, which reduce fuel intensity; and (3) expanded use of marginal biofuel blends and other low-emission fuels as part of the decarbonization pathway (IMO, 2025). Collectively, these drivers explain why the global emission factor for freightinggoods_sea_container is forecast to decline more substantially over 2025–2035 than the modest changes suggested by 2018–2024 data.

  Updated 2025-10-08

• Fuel · Australia · kWh · GJ

  Fuelgaseous Stationary Naturalgas(Pipeline)Metro emission factor trends — Australia

  In Australia, the emission factor for natural gas has not changed in recent years, however recent pilot studies alongside the Energy Networks Australia 20% RGT (renewable gas target) means our projection is for a very modest reduction by 2030.

  Updated 2025-10-16

• Materials · Global · kg

  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.

  Updated 2025-10-07

• Materials · Global · kg

  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).

  Updated 2025-10-10

• Materials · Global · kg

  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).

  Updated 2025-10-07

• Purchased goods & services · Global · currency

  Purchasedgoodsandservicesspend emission factor trends — Global

  This is a multi-factor emission factor trend that applies to all emission factors starting with 'purchasedgoodsandservicesspend'. It represents the overall decarbonisation trend for purchased goods and services across all categories.

  Updated 2025-01-01

• Utilities · Australia · kWh

  Utilities Electricity Grid trends — Australia (location-based)

  Australia is committed to reducing GHG emissions to 43% below 2005 levels by 2030. A key contribution to this target is the expanded Capacity Investment Scheme to deliver on the government’s target to achieve 82% renewable electricity by 2030.

  Updated 2025-06-01

• Utilities · Australia · kWh

  Utilities Electricity Grid trends — Australia (market-based)

  Australia’s utilities_electricity_grid residual factor could follow a sharper decarbonization path than the CER baseline suggests. Ember’s 2025 forecast envisions the residual market-based factor falling from 0.92 in 2025 to 0.75 by 2030 (Ember, 2025 Forecast), a roughly 19% reduction. This contrasts with CER’s projection of a gradual rise to about 0.98 by 2030 (CER, 2025 Forecast). The drivers underpinning a lower residual factor include: accelerated deployment of wind/solar and storage with ongoing coal retirements (AEMO, 2024); strengthened Safeguard Mechanism reforms tightening baselines for large emitters to accelerate abatement (DCCEEW, 2023–2025); rapid growth of corporate PPAs—around 60% of capacity contracted by 2025—locking in low-emission supply (Briggs, BRCA, 2025); and wholesale-market reforms and transmission investments that embed renewables into the market (AEMO, 2024). Together, these factors support a stronger decarbonization trajectory across au-nsw, au-vic, au-ql, au-sa, au-wa, au-tas, au-nt, and au-act.

  Updated 2026-02-21

• Utilities · United Kingdom · kWh

  Utilities Electricity Grid trends — United Kingdom (location-based)

  UK is committed to reducing GHG emissions to 80% below 1990 levels by 2050. A key contribution to this target is the Net Zero Strategy to deliver on the government’s target to achieve 100% renewable electricity by 2050.

  Updated 2025-06-01

• Utilities · United Kingdom · kWh

  Utilities Electricity Grid trends — United Kingdom (market-based)

  UK’s utilities_electricity_grid residual factor could follow a sharper decarbonisation path than the CER baseline suggests. Ember’s 2025 forecast envisions the residual market-based factor falling from 0.92 in 2025 to 0.75 by 2030 (Ember, 2025 Forecast), a roughly 19% reduction. This contrasts with CER’s projection of a gradual rise to about 0.98 by 2030 (CER, 2025 Forecast). The drivers underpinning a lower residual factor include: accelerated deployment of wind/solar and storage with ongoing coal retirements (AEMO, 2024); strengthened Safeguard Mechanism reforms tightening baselines for large emitters to accelerate abatement (DCCEEW, 2023–2025); rapid growth of corporate PPAs—around 60% of capacity contracted by 2025—locking in low-emission supply (Briggs, BRCA, 2025); and wholesale-market reforms and transmission investments that embed renewables into the market (AEMO, 2024). Together, these factors support a stronger decarbonization trajectory across uk-england, uk-scotland, uk-wales, and uk-northernireland.

  Updated 2026-02-21

• Utilities · Global · m3

  Utilities Water emission factor trends — Global

  Across all regions for utilities_water, 2025 DESNZ historic data show emission factors rose to 0.1913, following a dip in 2024 and a peak in 2023, yielding a net increase of around 28% from 2022 to 2025 (DESNZ, 2025). The year-to-year pattern suggests episodic electricity intensity tied to pumping and wastewater-treatment activity, with the 2024 decline reflecting gains from energy-efficiency measures and a progressively greener electricity mix for water operations (DESNZ, 2025). Policy and market factors are reinforcing this trajectory. Ofwat’s PR24 price controls explicitly incentivize energy efficiency, pumping upgrades, and energy recovery in treatment works to reduce carbon intensity (Ofwat, 2024). Concurrently, sector-wide Race to Net Zero roadmaps continue to push smarter operations and on-site generation in utilities, shaping investments that modulate emission factors over time (R2NZ, 2023–2025).

  Updated 2026-01-07