A policy booklet recently published by the UK’s opposition Conservative Party features a prominent financial figure concerning the “cost of net-zero” that appears to have been inflated by a factor of two due to a fundamental spreadsheet error.
The policy document, titled “The Right Way” and framed as a “common sense” guide for the party’s political direction, argues that what voters ultimately desire is a government competent enough to solve the problems for which it takes responsibility. Within its pages, the document critiques modern policymaking approaches, asserting that sophisticated economic modelling should never serve as a substitute for grounded political judgment. As part of this critique, the publication disparages various long-term estimates regarding the national cost of transitioning the economy to net-zero carbon emissions.
However, in its pursuit of challenging official projections, the Conservative document claims—incorrectly—that the government’s independent advisory body, the Climate Change Committee (CCC), originally placed the total cost of reaching net-zero at nearly £1tn. Specifically, the booklet states: “In 2020, the CCC estimated that its route to net-zero would cost £957bn.”
In reality, the CCC’s official 2020 estimate was precisely half that amount, standing at £478bn. Furthermore, the committee released a revised figure of £108bn last year, largely driven by the rapidly falling costs associated with electric vehicles (EVs) and low-carbon technologies.
Spreadsheet Error
The Conservative Party’s erroneous £957bn figure appears to trace its origins back to an accidental misinterpretation of a spreadsheet published by the CCC in December 2020 alongside its landmark Sixth Carbon Budget advice.
That 2020 spreadsheet contained comprehensive tables detailing the additional investments required to build a net-zero economy over a 30-year span from 2020 to 2050. These spanned multiple sectors, from low-carbon electricity generation to domestic heat pumps and electric vehicles. These extra capital expenditures, designated in the data as capital expenditure or CAPEX, added up to a cumulative total of £1.38tn over the three decades. Against these costs, the spreadsheet listed operational savings, designated as operational expenditure or OPEX, totaling £0.90tn.
When these figures were netted against one another over the 2020-2050 timeline, the combined CAPEX and OPEX figures yielded a net total of £478bn.
Alongside the annual sectoral figures for CAPEX and OPEX, the CCC’s spreadsheet also included a specific line item calculating the combined totals for each individual year. It appears that a subsequent analyst reviewing the data inadvertently added all of these rows together without accounting for the fact that annual totals were already embedded in the sheet, thereby counting the costs and savings twice.
This double-counting effectively doubled the true net cost of the transition, producing the £957bn figure that eventually found its way into the Conservative Party’s policy document.
When the CCC published its findings in 2020, it emphasized that the net cost of £478bn amounted to less than 1% of the UK’s total gross domestic product (GDP) over the 30-year period. The committee noted at the time that while the investment required was substantial, it would generate significant savings through reduced fossil-fuel imports and ultimately boost overall GDP by approximately 2%.
Subsequent analyses have continued to refine these projections. In 2025, the CCC updated its estimates, placing projected investment costs at £670bn and operating savings at £562bn, which brought the net total down to £108bn between 2025 and 2050—representing less than 0.2% of GDP. Earlier this year, the committee underscored that achieving net-zero emissions would cost less than a single major fossil-fuel price shock, while delivering economic and social benefits valued at £110bn annually.
Paper Trail
The erroneous £957bn figure cited in the Conservative document is formally referenced to the CCC’s 2020 advice on the UK’s carbon budget framework. However, a review of the official documents reveals that the figure does not exist within the primary text of the committee’s reports.
Tracing the online paper trail reveals that the earliest public use of the £957bn figure appeared in a January 2026 article published by The Spectator, written by retired engineer and self-described "accidental energy analyst" David Turver. Just a day after that article’s publication, Turver reiterated the mistaken figure in a formal report produced for the free-market Institute of Economic Affairs (IEA), citing a chart from the CCC’s 2020 supporting information data.
As established by the underlying spreadsheet architecture, however, the data supporting that specific chart totaled only £478bn. The discrepancy arose because the independent analysis mistakenly summed every row in the spreadsheet, duplicating the totals through double-counting.
Turver’s January 2026 report also triggered a wave of sensationalized headlines across various platforms, with some claims falsely asserting that net-zero would cost anywhere from £7.6tn to as much as £9tn. Those inflated figures relied on extreme and unrealistic theoretical assumptions, including the premise that fossil fuels, alongside the cars, home heating systems, and power plants that consume them, would carry zero baseline economic cost.
Following the initial circulation of Turver’s report and article in early 2026, the £957bn figure was repeated in March by the Great British Think Tank—an organization that uses the promotional tagline "data, not vibes" and asserts that all its figures are sourced directly from official public bodies.
Months later, the same doubled figure migrated into mainstream political discourse, ultimately appearing in the Conservative Party’s “Right Way” policy booklet in October 2026. The propagation of the figure highlights how calculation errors embedded in informal analytical reports can inadvertently travel through think-tank literature before being adopted into official political party publications.
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