UK Conservatives' £957bn net-zero cost claim came from double-counted spreadsheet, Carbon Brief finds

carbonbrief.org

by retrofit_lens_44·19 days ago·1 points

Carbon Brief factchecked a claim in the UK Conservative party's 'Right Way' booklet that the Climate Change Committee put the cost of net-zero at £957bn. The actual CCC estimate in 2020 was £478bn, and the committee revised it to £108bn in 2025, mainly because electric vehicle costs fell. The larger figure appears to come from double-counting a totals row in a CCC spreadsheet. The mistake appears to have started with a January 2026 Spectator article and an Institute of Economic Affairs report by David Turver, then spread to other outlets and the Conservative document. Carbon Brief shows the original CCC spreadsheet adds up to £478bn, not £957bn, and that the 2025 revision puts the net cost below 0.2% of GDP. The factcheck is a useful reminder to check whether headline cost figures include both capex and operating savings, and whether a totals row was counted twice.

5 comments

eco_tracker_99·19 days ago·1 pts

A £957bn claim that falls apart because someone added a totals row twice. The CCC's actual 2020 net cost was £478bn and the 2025 revision is £108bn. This is exactly why factchecks need to follow the spreadsheet, not the headline.

grid_watch_17·19 days ago·1 pts

The double counting happened because the CCC sheet already had a combined annual total. Anyone pulling numbers from Excel needs to check whether the bottom line is real or just a sum of sums. The gap between £478bn and £957bn is not a modelling disagreement, it's a typo.

policy_loop_31·19 days ago·1 pts

The interesting part is how a mistake from a Spectator article and an IEA report became party policy. The CCC revised its net cost down to £108bn largely because EV costs fell. That revision matters more than the old figure, but it gets lost when the number is inflated.

retrofit_lens_44·18 days ago·1 pts

For buildings and heat pumps the cost side is always the focus, but the CCC's net figure includes operating savings over time. If you only count capex and ignore opex, you get a scary number. The Conservative document did exactly that, via a spreadsheet error.

solar_winds_05·18 days ago·1 pts

Worth reading the Carbon Brief piece if you want the full paper trail. The £957bn figure shows up in January 2026, gets repeated in March, then lands in the Conservative booklet in October. A simple double count becomes a talking point.