A policy document recently published by the UK’s opposition Conservative Party features a prominent financial figure regarding 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 "Right Way" and framed as a "common sense" approach to governance, argues that what citizens ultimately desire is a government competent enough to solve the problems for which it takes responsibility. Within a section cautioning that sophisticated economic modeling should never be used as a substitute for direct political judgment, the document takes aim at various official estimates concerning the financial burden of transitioning the United Kingdom to a net-zero carbon economy.

In making its case, the Conservative publication asserts—incorrectly—that the Climate Change Committee (CCC), which serves as the British government’s official independent adviser on climate policy, had pegged the cost of achieving net-zero emissions at close to £1tn. Specifically, the booklet states: "In 2020, the CCC estimated that its route to net-zero would cost £957bn."

However, official records show that the CCC’s actual figure published in 2020 was exactly half of that amount, coming in at £478bn. Furthermore, the committee released a revised figure of £108bn last year, a significant downward adjustment largely driven by the rapidly falling costs associated with electric vehicles (EVs).

Spreadsheet Error

A detailed tracing of the numbers reveals that the Conservative Party’s erroneous claim originates from a compounding calculation error in an entirely separate report, which accidentally added up figures twice while utilizing a data spreadsheet published by the CCC in 2020.

The spreadsheet in question contains a comprehensive table mapping out the additional capital investments required to construct a net-zero economy over a 30-year period spanning from 2020 to 2050. These projected capital expenditures, categorized simply as "CAPEX," range from the development of low-carbon electricity generation infrastructure to the widespread installation of domestic heat pumps and the adoption of electric vehicles.

Over the three-decade timeframe, these extra capital expenditures sum to a total of £1.38tn. When evaluated against projected operational savings—listed in the data as "OPEX"—amounting to £0.90tn, the net combined total of CAPEX and OPEX figures over the 2020 to 2050 timeline yields a net cost of £478bn.

The root of the error appears to lie in the spreadsheet’s layout. In addition to listing annual sectoral CAPEX and OPEX figures, the CCC’s 2020 spreadsheet also included a distinct line providing combined totals for each individual year. An analysis of the error suggests that an analyst inadvertently added all of these individual rows and totals together, resulting in the operational savings and capital costs being counted twice over.

This double-counted sum results in a total figure of £957bn for the cost of net-zero—precisely the figure that subsequently found its way into the Conservative Party booklet.

At the time the original figures were published in late 2020, the CCC emphasized that the net cost of £478bn represented less than 1% of the United Kingdom’s gross domestic product (GDP) spread across the 30-year duration. The committee argued at the time that the substantial investments required would not only generate direct savings by slashing reliance on expensive fossil-fuel imports, but would also provide an overall net boost to national GDP of approximately 2%.

Subsequent updates by the committee have only further shifted the economic outlook. In 2025, the CCC revised its cumulative investment costs and operating savings estimates to £670bn and £562bn respectively, leaving a net total of £108bn across the 2025 to 2050 period. This reduced net cost amounts to less than 0.2% of the nation’s GDP. Additionally, earlier this year, the committee noted that pushing ahead with domestic emissions cuts to reach net-zero would ultimately cost less than enduring a single major fossil-fuel price shock, while delivering wider ancillary benefits valued at £110bn annually.

Paper Trail

The erroneous citation included in the Conservative Party document formally references the CCC’s 2020 advice regarding the UK’s sixth carbon budget. However, that official advisory document does not contain the £957bn figure anywhere within its text.

A broader investigation into the digital footprint of the £957bn figure reveals that its earliest appearance online can be traced to an article published on January 12, 2026, in The Spectator. That piece was authored by David Turver, a retired engineer who describes himself as an "accidental energy analyst."

Just one day after that article was published, Turver repeated the mistaken figure in a formal policy report compiled for the free-market Institute of Economic Affairs (IEA). That report explicitly cited figure 5.3 of the CCC’s 2020 carbon budget supporting information.

Nevertheless, as the underlying spreadsheets demonstrate, the data corresponding to figure 5.3 only amounts to £478bn—exactly half of what Turver’s report asserted. The discrepancy stems from the same methodological oversight, wherein the annual summary rows were mistakenly added into the cumulative sum, effectively double-counting the transition expenses.

Turver’s published report subsequently catalyzed a wider wave of misleading headlines across various media outlets and online commentary platforms, with some claims asserting that net-zero would carry an astronomical price tag ranging from £7.6tn to as high as £9tn. These even higher figures relied on implicit assumptions that fossil fuels, along with the cars, home heating boilers, and power generation plants that consume them, would essentially cost nothing to replace or operate.

Following the circulation of Turver’s report and related commentary in early 2026, the erroneous £957bn figure was repeated in March by an organization known as the Great British Think Tank. The group, which promotes a motto emphasizing "data, not vibes" and maintains that all of its figures are strictly sourced from official public bodies, helped institutionalize the figure before it was ultimately adopted by the Conservative Party in its "Right Way" publication in October 2026.