A policy booklet recently published by the UK’s opposition Conservative party features a prominent figure regarding the "cost of net-zero" that appears to have been inflated by 100 percent due to a basic spreadsheet error.

The publication, a "common sense" policy document titled "The Right Way," argues that what citizens ultimately want is a government competent enough to solve the problems for which it takes responsibility. Within its pages, the document cautions against letting sophisticated economic modelling act as a substitute for political judgment, utilizing this perspective to disparage various independent and official estimates concerning the financial burden of transitioning the United Kingdom to a net-zero carbon economy.

However, the Conservative document stumbles into factual inaccuracy when it attempts to cite the government’s official climate adviser, the Climate Change Committee (CCC). According to the booklet, the CCC estimated back in 2020 that its specific route to achieving net-zero emissions would cost close to one trillion pounds. Specifically, the text states that in 2020, the CCC estimated its pathway would cost £957bn.

In reality, the CCC’s actual 2020 estimate was exactly half of that amount—totalling £478bn. Furthermore, the committee published a revised figure last year dropping the projected net cost down to £108bn, a downward adjustment driven largely by the rapidly falling costs associated with electric vehicles and low-carbon technologies.

Spreadsheet Error

The root of the Conservative party’s erroneous claim can be traced back to an accidental double-counting error originating from a data spreadsheet published by the CCC in late 2020.

That specific spreadsheet contained a comprehensive table outlining the additional capital investments required to construct a decarbonized economy. These figures spanned a wide array of sectors, ranging from low-carbon electricity generation infrastructure to domestic heat pumps and electric vehicles.

In the document, these extra capital expenditures were designated as "CAPEX" and were calculated to total roughly £1.38tn over a thirty-year timeframe stretching from 2020 to 2050. These capital investments were then set against projected operational savings, categorized as "OPEX," which were valued at approximately £0.90tn over the same multi-decade period. When properly balanced—subtracting the operational savings from the gross capital expenditures—the combined net figure for the net-zero transition came to £478bn.

Yet, alongside the annual sectoral CAPEX and OPEX breakdowns, the CCC spreadsheet also included a distinct line providing combined totals for each individual year. An analysis of the data trail indicates that an analyst at some point accidentally added all of these annual figures together without accounting for the fact that the spreadsheet already incorporated sub-totals. Consequently, the operational savings and gross costs were inadvertently counted twice.

This double-counted calculation resulted in a staggering total of £957bn for the cost of net-zero. This inflated figure is precisely what eventually found its way into the Conservative party’s policy booklet.

When the CCC originally published its Sixth Carbon Budget advice in 2020, it emphasized that the actual net cost of £478bn amounted to less than 1 percent of the UK’s gross domestic product over the course of thirty years. The committee underscored at the time that the massive initial capital investment required would not only generate substantial savings through reduced reliance on costly fossil-fuel imports, but it would also provide a net boost to overall GDP by approximately 2 percent.

Subsequent updates from the advisory body have only reinforced these economic projections. In 2025, the CCC revised its estimates for investment costs and operating savings to £670bn and £562bn respectively, yielding a significantly reduced net total of £108bn over the 2025-2050 period—representing less than 0.2 percent of GDP. Earlier this year, the committee reiterated that pursuing deep emissions cuts to achieve net-zero would ultimately cost the country less than a single major fossil-fuel price shock, while delivering direct consumer and systemic benefits worth roughly £110bn annually.

Paper Trail

The provenance of the £957bn figure in conservative policy circles reveals a clear paper trail of repeated miscalculations across multiple independent publications and think tanks.

Although the Conservative party document formally references the CCC’s 2020 advice on the UK’s sixth carbon budget to justify its claims, the actual source material does not contain the £957bn figure. Instead, investigative tracking indicates that the earliest online appearance of the inflated £957bn metric emerged in an article published on January 12, 2026, in The Spectator, written by retired engineer and self-described accidental energy analyst David Turver.

Just one day after that article was published, Turver repeated the mistaken number in a formal report commissioned by the free-market Institute of Economic Affairs. That report explicitly cited figure 5.3 of the CCC’s 2020 supporting information. However, because the underlying spreadsheet for figure 5.3 totaled only £478bn, Turver’s methodology—summing every individual row without adjusting for the pre-calculated annual total lines—effectively duplicated the entire dataset.

Turver’s initial reports also catalyzed a broader wave of widely shared, inaccurate headlines in early 2026. Various commentary pieces claimed that transitioning to net-zero would cost anywhere from £7.6tn to as much as £9tn. Those extreme figures relied on implicit, highly unrealistic assumptions that treated fossil fuels, along with the cars, domestic boilers, and power plants that consume them, as entirely free resources.

Following the circulation of Turver’s report and subsequent media coverage in January 2026, the erroneous £957bn figure was adopted and republished in March by the Great British Think Tank. That organization, which promotes a motto emphasizing empirical data over subjective political narratives and claims to source every figure directly from official public bodies, helped cement the flawed statistic within broader right-of-centre policy discourse. From there, the inflated metric was embedded directly into the Conservative party’s "Right Way" booklet.

The propagation of this statistical error highlights the ongoing challenges surrounding public debates over climate policy economics, where complex multi-decade modelling data from official advisory bodies can occasionally be misinterpreted and amplified across political networks before reaching mainstream policy manifestos.