2026 vs 2025 DEFRA Emissions Factor Comparison: What’s Driving the Latest Changes?
2026 DEFRA Emissions Factor Update: What the Latest Data Reveals About UK Decarbonisation
Each year, the Department for Environment, Food and Rural Affairs (DEFRA) releases a set of Government Greenhouse Gas (GHG) Conversion Factors (commonly known as Emission Factors).
On 11th June 2026, DEFRA released the set of emissions factors for 2026, which provide a valuable snapshot of how the UK’s carbon landscape is evolving. This year’s update is particularly notable, not only for continued reductions in electricity-related emissions, but also for methodological changes that directly influence reported carbon footprints.
For organisations tracking Scope 1, 2, and/or 3 emissions, understanding these changes is essential for accurate carbon reporting and meaningful decarbonisation planning.
What Are Emissions Factors?
Emissions factors, also known as “conversion factors”, are numerical values used to convert quantities of one unit into another. In the context of carbon emissions, these factors translate various activities, such as energy consumption or transportation, into an equivalent amount of carbon dioxide (CO2) emissions.
Let’s say you want to calculate the emissions associated with a 3,000 km flight, travelling economy class. Conveniently for us, the Department for Environment, Food & Rural Affairs (DEFRA) has an emission factor for an average long-haul economy journey of 0.11704 kgCO₂e per passenger km. So we can simply multiply the two and work out that the footprint of your journey was 351.12 kgCO₂e.
What Are They Used For?
Emissions factors are essential for measuring and reporting greenhouse gas (GHG) emissions. They are used in carbon accounting, helping organisations understand their carbon footprint and enabling them to set and achieve reduction targets.
For example, an emission factor for electricity might reflect the average carbon intensity of the UK's energy grid, while a factor for a specific vehicle type would account for its fuel efficiency and emissions per mile. These factors are crucial for understanding the relative impact of different actions and for making informed decisions about reducing emissions.
KEY TAKEAWAYS
- UK electricity emissions factors have fallen significantly, driven by grid decarbonisation and methodological updates.
- Electrified activities such as EV travel and rail fall significantly. https://carbongreenlimited.sharepoint.com/contentstorage/CSP_7f4e631d-4109-4215-8f8c-872f180762f7/Document Library/knowledge/a89eda1c-cbf3-4caf-8945-e55137deeb03/MyCarbon Messaging %26 Positioning Guide 2025 V3.docx
- Scope 1 fuels show only marginal changes, indicating stability in direct emissions factors.
- Scope 3 results are mixed, with transport and waste showing varied changes depending on updated datasets.
The Headline: A Step Change in Electricity Emissions
The most significant movement in the 2026 update is seen in electricity emissions. The UK electricity factor has reduced from 0.177 to 0.131 kgCO₂e/kWh, representing a substantial decrease (26%).
This reduction is driven by a combination of factors:
- The UK electricity mix shifting significantly towards renewables.
- A methodological shift reducing data lag from two years to one (meaning more of the newly deployed renewables get counted)
- Updated grid loss assumptions
- Improved accounting of imports and exports
- Correction of a small double-counting issue that affected autogenerators (i.e. a minor methodological refinement within the electricity calculation, contributing to a portion of the wider methodology-driven reduction in 2026 emissions factors, rather than indicating any material inaccuracy in previous values)
Across the electricity factor, around 6–7 percentage points of the overall reduction are attributed to methodological changes, including this correction, with the majority driven by underlying grid decarbonisation.
What this means in practice
Organisations with high electricity consumption will likely see a noticeable reduction in Scope 2 emissions this year. This reduction is primarily driven by the decrease in the UK electricity emission factor, rather than any change in underlying activity.
As a result, reported emissions may fall even if energy consumption remains the same. This is important to recognise when interpreting year-on-year performance.
In practice, organisations should:
- Avoid attributing these reductions to operational decarbonisation efforts alone
- Clearly distinguish between reductions driven by emission factor changes and those driven by actual activity reduction
Organisations should also not retrospectively apply the 2026 emission factors to previously reported inventories, unless formally restating their baseline. Instead, the 2026 update should be treated as a new reporting cycle, with any changes clearly explained in disclosures.
Scope 1: Stability in Direct Emissions
Scope 1 emissions factors remain largely stable in 2026, with only marginal movements across key fuels:
- Natural gas shows a slight decrease (~ - 0.4%)
- Diesel shows a small increase (~ +0.5%)
- Petrol shows a slight increase (~ +0.3%)
- Vehicle fuel factors generally decrease slightly for example:
- Average diesel car: ~ -0.2%
- Average petrol car: ~ -0.7%
These changes are not driven by methodological shifts, but rather minor updates to underlying datasets.
Key insight
Unlike electricity, direct combustion emissions are not seeing rapid structural change. This reinforces the importance of active decarbonisation measures such as fuel switching, electrification, or efficiency improvements for Scope 1.
Scope 2 and Electrification: Accelerating Impact
The decline in electricity emissions has a knock-on effect across all electrified activities.
For example:
Battery electric vehicle emissions have decreased significantly (~ -27%)
Plug-in hybrid emissions have also reduced (~ -25%)
Electric rail emissions have decreased (~ -13%), while London Underground emissions show a more substantial reduction (~ -44%)
Key insight
Electrification continues to strengthen as a decarbonisation pathway. As the grid improves, the carbon impact of switching from fossil fuels to electricity becomes even stronger.
Scope 3: A Mixed and Nuanced Picture
Scope 3 categories show a more varied set of changes:
Waste
- Slight decreases in combustion-related emissions (~ -0.7%)
- Marginal increases in landfill emissions (~ +0.01%)
These reflect updated UK datasets rather than methodological changes.
Travel
- Air travel remains unchanged
- Rail emissions decrease significantly (~ -13%)
- Bus emissions decrease slightly (~ -2%), while taxi emissions remain unchanged
Freight and Distribution
- Diesel van increase slightly (~ 0.6%)
- HGV emissions increase (~ +1.9%)
- Petrol vans show a decrease (~ 2%)
- Freight rail emissions change due to electricity factor updates (~ -7%)
Other categories
- Water, hotels, and several service-related factors remain unchanged
- Homeworking emissions decrease slightly due to updated electricity factors (~ -3%)
Key insight
Scope 3 continues to reflect underlying data improvements rather than systemic decarbonisation across all categories. This reinforces the complexity of value chain emissions and the need for targeted interventions.
What This Means for Reporting and Strategy?
For organisations reporting emissions or setting decarbonisation strategies, the 2026 update has several practical implications. The most significant change is in UK electricity, where the factor falls by 26%. DEFRA attributes most of this reduction to grid decarbonisation between 2023 and 2024, while the remaining 6 to 7 percentage points reflect methodological changes, improvements and corrections.
1. Treat lower electricity emissions carefully: Organisations with high electricity use are likely to report lower Scope 2 emissions in 2026, even if consumption remains broadly unchanged. In other words, some reported reduction will come from a lower emission factor rather than from operational improvement. That distinction matters when reporting progress internally or externally.
2. Be cautious when comparing with historic reporting: The 2026 electricity change reflects a mixture of real grid decarbonisation and updated methodology, including reduced data lag, revised treatment of imports and exports, updated grid loss assumptions, and correction of a small double-counting issue affecting autogenerators. That means organisations should be cautious about comparing 2026 figures directly with prior years without explanation. If previous inventories have already been published, the safer approach is usually to disclose the driver of change clearly rather than present the reduction as purely operational.
3. Reassess electrification strategies: This year’s update reinforces the long-term direction of travel. As grid electricity becomes less carbon intensive, the relative benefit of electrification increases. This is reflected not just in purchased electricity, but across battery electric vehicles, plug-in hybrids, rail and London Underground factors. For organisations considering fleet transition, electric heating, or wider fuel switching, the strategic case is now even stronger.
4. Maintain focus on Scope 3: Outside electricity-linked activities, many Scope 3 factors remain broadly stable or change only marginally. Waste, freight and water categories show limited movement overall, while flights and hotel stays remain unchanged in your comparison. This means organisations should not expect factor updates alone to drive meaningful Scope 3 reductions. Progress here still depends on supplier engagement, procurement choices, travel policy, logistics optimisation and operational change.
5. Communicate transparently: If a client asked how to present this year’s results, the advice would be simple: separate reductions driven by changed emission factors from reductions driven by genuine activity or efficiency improvements. That gives stakeholders a more credible picture of performance and avoids overstating progress. This is especially important in a year where methodological updates contribute materially to the reported fall in electricity-related emissions.
6. Use the update as a strategy review point: Rather than treating the 2026 factors as a routine technical refresh, organisations should use them as a trigger to review the logic of their decarbonisation plan. The message from this year’s data is clear. Electricity-linked emissions are falling faster, direct combustion remains comparatively stable, and most Scope 3 categories still require deliberate intervention. That should influence where effort and investment are prioritised next.
Ready to understand what these updates mean for your footprint?
At MyCarbon, we help organisations navigate changes in emissions factors, ensuring reporting remains accurate, credible, and aligned with your wider decarbonisation strategy.
Speak to our team to review your 2026 emissions and identify where real carbon reductions can be achieved.