Grid carbon intensity by region: the cleanest times to charge an EV
The same kWh of grid electricity comes with very different emissions depending on where and when it is used. This page shows, for each of the 14 distribution network areas in Great Britain, the average carbon intensity over the last 12 months and how it changes through the day.
Across Great Britain the average was 125 g CO2/kWh, and 36% of half-hours were rated low or very low. On average the cleanest three hours were 11:00 to 14:00 (104 g) and the dirtiest 18:00 to 21:00 (153 g).
South Scotland averaged 8 g CO2/kWh, with wind 67% of its modelled generation mix. South Wales averaged 251 g, with gas 64%.
Average carbon intensity by network area
| Network area | Average g/kWh | Low or very low | 08:00-18:00 | 00:00-06:00 | Cleanest 3 hours | Largest sources |
|---|---|---|---|---|---|---|
| South Scotland | 8 | 99% | 9 | 6 | 00:00 to 03:00 (6) | wind 67%, nuclear 26% |
| North Scotland | 13 | 95% | 15 | 11 | 22:00 to 01:00 (9) | wind 93%, gas 3% |
| North East England | 27 | 95% | 30 | 24 | 00:00 to 03:00 (23) | wind 32%, imports 30% |
| North West England | 45 | 88% | 48 | 36 | 00:00 to 03:00 (35) | wind 41%, nuclear 36% |
| North Wales & Merseyside | 72 | 71% | 73 | 55 | 01:00 to 04:00 (52) | wind 55%, nuclear 18% |
| West Midlands | 115 | 49% | 110 | 101 | 11:00 to 14:00 (96) | wind 39%, gas 27% |
| Yorkshire | 119 | 38% | 120 | 106 | 00:00 to 03:00 (105) | biomass 37%, wind 33% |
| East England | 122 | 36% | 123 | 108 | 02:00 to 05:00 (104) | wind 37%, gas 21% |
| London | 143 | 24% | 135 | 136 | 11:00 to 14:00 (123) | imports 30%, gas 28% |
| South East England | 160 | 16% | 147 | 157 | 11:00 to 14:00 (133) | imports 43%, gas 32% |
| East Midlands | 175 | 22% | 168 | 159 | 11:00 to 14:00 (148) | gas 39%, wind 30% |
| South England | 177 | 15% | 153 | 184 | 11:00 to 14:00 (132) | gas 40%, imports 25% |
| South West England | 247 | 9% | 179 | 295 | 11:00 to 14:00 (141) | gas 62%, solar 19% |
| South Wales | 251 | 16% | 225 | 251 | 11:00 to 14:00 (196) | gas 64%, wind 24% |
| GB | 125 | 36% | 117 | 117 | 11:00 to 14:00 (104) | wind 34%, gas 26% |
Average by hour of day (g CO2/kWh)
Each cell is the 12-month average for that clock hour. Lower is cleaner. In the Midlands, the south of England and South Wales the lowest averages fall around midday; in almost every area the highest come in the late afternoon or early evening.
| Network area | 00:00 | 03:00 | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|---|---|
| South Scotland | 6 | 6 | 7 | 8 | 8 | 10 | 10 | 7 |
| North Scotland | 10 | 11 | 15 | 15 | 15 | 15 | 13 | 11 |
| North East England | 23 | 23 | 28 | 29 | 29 | 31 | 30 | 25 |
| North West England | 36 | 35 | 45 | 45 | 43 | 49 | 60 | 50 |
| North Wales & Merseyside | 55 | 53 | 68 | 67 | 61 | 79 | 107 | 85 |
| West Midlands | 104 | 97 | 119 | 108 | 95 | 112 | 150 | 137 |
| Yorkshire | 106 | 104 | 119 | 117 | 111 | 123 | 144 | 128 |
| East England | 114 | 104 | 122 | 128 | 116 | 116 | 145 | 136 |
| London | 139 | 131 | 152 | 136 | 122 | 134 | 172 | 164 |
| South East England | 158 | 151 | 175 | 145 | 132 | 149 | 190 | 181 |
| East Midlands | 163 | 154 | 182 | 165 | 147 | 172 | 219 | 200 |
| South England | 184 | 180 | 201 | 152 | 130 | 157 | 207 | 209 |
| South West England | 295 | 292 | 301 | 183 | 138 | 184 | 273 | 313 |
| South Wales | 257 | 244 | 274 | 231 | 195 | 224 | 297 | 291 |
| GB | 119 | 113 | 133 | 116 | 103 | 118 | 153 | 144 |
What it means for charging at your site
- Workplace and destination chargers are used mostly in the daytime. In the south of England, the Midlands and South Wales that is when average intensity is lowest. Depot chargers used overnight see the night-time figure.
- Smart chargers can delay or slow charging to follow a tariff or a carbon signal. Charging when intensity is low lowers the emissions linked to the electricity used, on this average measure.
- The government's conversion factor for grid electricity, used in most UK company carbon reports, is a single annual UK figure. Shifting charging times does not change a report that uses it.
How the figures are worked out
- NESO publishes a carbon intensity estimate for every half-hour in each network area. Regional values are modelled from generation, flows between regions and demand; they are estimates, not metered readings.
- We average every half-hour in the 12 months shown. Hours are on the UK clock, so they follow British Summer Time. The cleanest window is the run of three clock hours with the lowest average.
- Ratings of low or very low use NESO's own bands for each half-hour. The generation mix is NESO's modelled share of each source in the area, averaged over the same half-hours.
- Northern Ireland is on a separate grid and is not covered by this data.
Sources
- Carbon Intensity API, regional intensity, National Energy System Operator (NESO) (CC BY 4.0). Retrieved 2026-10-20.
- Government conversion factors for company reporting, DESNZ.