Insights
Understanding the UK grid carbon emissions data.
2025 figures show why time and place now matter more than ever.
Reporting carbon emissions is a regular commitment for large organisations, but where you are in the UK and what time of day you use electricity can make a significant difference to your level of emissions.
Using standard annual Scope 2 emission factors for your Streamlined Energy and Carbon Reporting (SECR) you are not reporting your actual carbon emissions.
And you could be missing out.
Using local and time-based UK National Grid NESO carbon emissions data, we have found that, for example, an office in London uses around 25% less carbon than it would be reported to have used when using the national average.
To help explore these regional and time-based differences in more detail, we have updated our public UK grid carbon analytics dashboard with 2025 data. It allows users to explore how 2025 compares to previous years, examine seasonal and regional variations in carbon intensity across the grid, and test how different carbon accounting approaches can materially affect reported emissions.
Our 2025 findings.
At a national level, grid carbon intensity has broadly stagnated between 2024 and 2025. A similar generation mix, combined with an increase in national electricity demand of around 3%, resulted in an average grid intensity of 129 gCO₂e/kWh (Scope 2, generation-based).
The figures shown are generation-based and load-weighted, meaning they reflect the technologies actually running during periods of highest demand, rather than simple annual averages.
For high-energy users, this is a critical shift. A relatively small number of high-demand hours can drive a disproportionate share of electricity-related emissions, because these are the moments when higher-carbon generation is most likely to be on the system.
Opportunities to lower your emissions.
Understanding this opens up new opportunities for asset owners to target carbon reduction where it has the greatest real impact.
Some regional movements stand out.
Regions with notable increases:
South East England:
140 → 161 gCO₂e/kWh (+15%)
London:
129 → 142 gCO₂e/kWh (+11%)
North Scotland:
31 → 47 gCO₂e/kWh (+52%)
North Scotland remains a low-carbon region overall, but the increased volatility suggests higher-carbon generation coincided more frequently with peak demand periods in 2025.
For electrically heated offices, residential schemes or other peak-sensitive assets in these regions, this means the carbon impact of each kilowatt-hour consumed during high-demand periods was higher in 2025 than in 2024, even where total annual electricity use remained unchanged. This reinforces further that “low‑carbon grid” is not a static attribute: the timing and shape of demand increasingly determine whether an asset genuinely aligns with a low‑carbon electricity system.
Regions with reductions:
South West England:
239 → 220 gCO₂e/kWh (−8%)
South Wales:
259 → 252 gCO₂e/kWh (−3%)
East Midlands:
208 → 197 gCO₂e/kWh (−5%)
Why this matters for low-carbon strategies.
What this analysis reinforces is that when and where electricity is consumed increasingly matters as much as how much is consumed. National annual averages alone are no longer sufficient for credible decarbonisation strategies. In practice, this means that two assets with identical annual electricity demand can have very different carbon impacts depending on where they are located and how their demand aligns with the grid.
1. More credible electrification decisions. By understanding how grid carbon intensity varies by location and time, we can help clients identify where and when electrification delivers the greatest carbon benefit, rather than assuming all electrification is equally low-carbon everywhere.
This helps avoid apparent carbon improvements that are driven by annual demand reductions, while electricity use increasingly coincides with high-carbon peak periods. For example, electrifying heating or EV charging without time-based control can increase demand during evening peaks, when grid carbon intensity is typically highest.
2. Targeted use of flexibility to reduce real emissions. The analysis highlights when grid carbon intensity is generally highest and lowest. We can then use this insight to inform the sizing and operation of flexibility measures such as batteries, thermal storage and smart controls, so they reduce real-world emissions rather than just theoretical ones.
In North Scotland, for example, the grid was zero-carbon for more than 60% of the year while peak demand periods were more likely to coincide with higher-carbon generation.
Designing assets and controls around this volatility allows demand to be actively shifted towards genuinely low-carbon periods, turning demand-side flexibility into a practical decarbonisation lever rather than a theoretical one.
3. Readiness for evolving carbon reporting frameworks. With the GHG Protocol currently reviewing Scope 2 guidance and considering more granular, time-based approaches, this type of analysis helps clients understand how future reporting requirements could affect them- and how operational strategies adopted today may reduce future reporting risk.
Importantly, strategies that reduce demand during high-carbon periods are likely to remain robust under any move towards more time resolved or location based reporting, helping futureproof decisions made today.
4. Aligning cost optimisation with carbon reduction. Recent Contracts for Difference results shows that low-carbon generation is increasingly the lowest-cost form of new electricity supply. DESNZ announced that new onshore wind has been agreed at £72.24/MWh and new solar at £65.23/MWh both significantly below the £147/MWh cost of building and operating new gas power stations.
As a result, periods of lower grid carbon intensity increasingly coincide with lower wholesale electricity prices. For asset owners, this strengthens the case for designing buildings and energy systems that can actively respond to time-based signals. Demand flexibility, storage and smart controls are no longer purely environmental measures — they are becoming financial optimisation tools as well.
In practice, strategies that shift consumption towards low-carbon periods are increasingly likely to reduce operating costs at the same time, creating alignment between decarbonisation objectives and commercial performance.
For a detailed exploration of the methodological differences between static, time-of-use and regional carbon accounting – and the implications for building-level decision-making – our paper presented at the CIBSE Technical Symposium 2025 provides further technical depth and case study analysis.
We’d be interested to hear:
What stands out to you when exploring the dashboard and UK grid carbon?
LET’S TALK:
JacquesLe-Van@hoarelea.com