Electric heat pumps are set to play a key role in the UK’s climate strategy, as well as cutting the nation’s reliance on imported fossil fuels.
Heat pumps took centre-stage in the UK government’s recent “warm homes plan”, which said that they could also help cut household energy bills by “hundreds of pounds” a year.
Similarly, innovation agency Nesta estimates that typical households could cut their annual energy bills nearly £300 a year, by switching from a gas boiler to a heat pump.
Yet there has been widespread media coverage in the Times, Sunday Times, Daily Express, Daily Telegraph and elsewhere of a report claiming that heat pumps are “more expensive” to run.
The report is from the Green Britain Foundation set up by Dale Vince, owner of energy firm Ecotricity, who campaigns against heat pumps and invests in “green gas” as an alternative.
One expert tells Carbon Brief that Vince’s report is based on “flimsy data”, while another says that it “combines a series of worst-case assumptions to present an unduly pessimistic picture”.
This factcheck explains how heat pumps can cut bills, what the latest data shows about potential savings and how this information was left out of the report from Vince’s foundation.
How heat pumps can cut bills
Heat pumps use electricity to move heat – most commonly from outside air – to the inside of a building, in a process that is similar to the way that a fridge keeps its contents cold.
This means that they are highly efficient, adding three or four units of heat to the house for each unit of electricity used. In contrast, a gas boiler will always supply less than one unit of heat from each unit of gas that it burns, because some of the energy is lost during combustion.
This means that heat pumps can keep buildings warm while using three, four or even five times less energy than a gas boiler. This cuts fossil-fuel imports, reducing demand for gas by at least two-fifths, even in the unlikely scenario that all of the electricity they need is gas-fired.
Since UK electricity supplies are now the cleanest they have ever been, heat pumps also cut the carbon emissions associated with staying warm by around 85%, relative to a gas boiler.
Heat pumps are, therefore, the “central” technology for cutting carbon emissions from buildings.
While heat pumps cost more to install than gas boilers, the UK government’s recent “warm homes plan” says that they can help cut energy bills by “hundreds of pounds” per year.
Similarly, Nesta published analysis showing that a typical home could cut its annual energy bill by £280, if it replaces a gas boiler with a heat pump, as shown in the figure below.
Nesta and the government plan say that significantly larger savings are possible if heat pumps are combined with other clean-energy technologies, such as solar and batteries.
Both the government and Nesta’s estimates of bill savings from switching to a heat pump rely on relatively conservative assumptions.
Specifically, the government assumes that a heat pump will deliver 2.8 units of heat for each unit of electricity, on average. This is known as the “seasonal coefficient of performance” (SCoP).
This figure is taken from the government-backed “electrification of heat” trial, which ran during 2020-2022 and showed that heat pumps are suitable for all building types in the UK.
(The Green Britain Foundation report and Vince’s quotes in related coverage repeat a number of heat pump myths, such as the idea that they do not perform well in older properties and require high levels of insulation.)
Nesta assumes a slightly higher SCoP of 3.0, says Madeleine Gabriel, the organisation’s director of sustainable future. (See below for more on what the latest data says about SCoP in recent installations.)
Both the government and Nesta assume that a home with a heat pump would disconnect from the gas grid, meaning that it would no longer need to pay the daily “standing charge” for gas. This currently amounts to a saving of around £130 per year.
Finally, they both consider the impact of a home with a heat pump using a “smart tariff”, where the price of electricity varies according to the time of day.
Such tariffs are now widely available from a variety of energy suppliers and many have been designed specifically for homes that have a heat pump.
Such tariffs significantly reduce the average price for a unit of electricity. Government survey data suggests that around half of heat-pump owners already use such tariffs.
This is important because on the standard rates under the price cap set by energy regulator Ofgem, each unit of electricity costs more than four times as much as a unit of gas.
The ratio between electricity and gas prices is a key determinant of the size and potential for running-cost savings with a heat pump. Countries with a lower electricity-to-gas price ratio consistently see much higher rates of heat-pump adoption.
(Decisions taken by the UK government in its 2025 budget mean that the electricity-to-gas ratio will fall from April, but current forecasts suggest it will remain above four-to-one.)
In contrast, Vince’s report assumes that gas boilers are 90% efficient, whereas data from real homes suggests 85% is more typical. It also assumes that homes with heat pumps remain on the gas grid, paying the standing charge, as well as using only a standard electricity tariff.
Prof Jan Rosenow, energy programme leader at the University of Oxford’s Environmental Change Institute, tells Carbon Brief that Vince’s report uses “worst-case assumptions”. He says:
“This report cherry-picks assumptions to reach a predetermined conclusion. Most notably, it assumes a gas boiler efficiency of 90%, which is significantly higher than real-world performance…Taken together, the analysis combines a series of worst-case assumptions to present an unduly pessimistic picture.”
Similarly, Gabriel tells Carbon Brief that Vince’s report is based on “flimsy data”. She explains:
“Dale Vince has drawn some very strong conclusions about heat pumps from quite flimsy data. Like Dale, we’d also like to see electricity prices come down relative to gas, but we estimate that, from April, even a moderately efficient heat pump on a standard tariff will be cheaper to run than a gas boiler. Paired with a time-of-use tariff, a heat pump could save £280 versus a boiler and adding solar panels and a battery could triple those savings.”
What the latest data shows about bill savings
The efficiency of heat-pump installations is another key factor in the potential bill savings they can deliver and, here, both the government and Vince’s report take a conservative approach.
They rely on the “electrification of heat” trial data to use an efficiency (SCoP) of 2.8 for heat pumps. However, Rosenow says that recent evidence shows that “substantially higher efficiencies are routinely available”, as shown in the figure below.
Detailed, real-time data on hundreds of heat pump systems around the UK is available via the website Heat Pump Monitor, where the average efficiency – a SCoP of 3.9 – is much higher.
Homes with such efficient heat-pump installations would see even larger bill savings than suggested by the government and Nesta estimates.
Academic research suggests that there are simple and easy-to-implement reasons why these systems achieve much higher efficiency levels than in the electrification of heat trial.
Specifically, it shows that many of the systems in the trial have poor software settings, which means they do not operate as efficiently as their heat pump hardware is capable of doing.
The research suggests that heat pump installations in the UK have been getting more and more efficient over time, as engineers become increasingly familiar with the technology.
It indicates that recently installed heat pumps are 64% more efficient than those in early trials.
Notably, the Green Britain Foundation report only refers to the trial data from the electrification of heat study carried out in 2020-22 and the even earlier “renewable heat premium package” (RHPP). This makes a huge difference to the estimated running costs of a heat pump.
Carbon Brief analysis suggests that a typical household could cut its annual energy bills by nearly £200 with a heat pump – even on a standard electricity tariff – if the system has a SCoP of 3.9.
The savings would be even larger on a smart heat-pump tariff.
In contrast, based on the oldest efficiency figures mentioned in the Green Britain Foundation report, a heat pump could increase annual household bills by as much as £200 on a standard tariff.
To support its conclusions, the report also includes the results of a survey of 1,001 heat pump owners, which, among other things, is at odds with government survey data. The report says “66% of respondents report that their homes are more expensive to heat than the previous system”.
There are several reasons to treat these findings with caution. The survey was carried out in July 2025 and some 45% of the heat pumps involved were installed between 2021-23.
This is a period during which energy prices surged as a result of Russia’s invasion of Ukraine and the resulting global energy crisis. Energy bills remain elevated as a result of high gas prices.
The wording of the survey question asks if homes are “more or less expensive to heat than with your previous system” – but makes no mention of these price rises.
The question does not ask homeowners if their bills are higher today, with a heat pump, than they would have been with the household’s previous heating system.
If respondents interpreted the question as asking whether their bills have gone up or down since their heat pump was installed, then their answers will be confounded by the rise in prices overall.
There are a number of other seemingly contradictory aspects of the survey that raise questions about its findings and the strong conclusions in the media coverage of the report.
For example, while only 15% of respondents say it is cheaper to heat their home with a heat pump, 49% say that one of the top three advantages of the system is saving money on energy bills.
In addition, 57% of respondents say they still have a boiler, even though 67% say they received government subsidies for their heat-pump installation. It is a requirement of the government’s boiler upgrade scheme (BUS) grants that homeowners completely remove their boiler.
The government’s own survey of BUS recipients finds that only 13% of respondents say their bills have gone up, whereas 37% say their bills have gone down, another 13% say they have stayed the same and 8% thought that it was too early to say.
The post Factcheck: What it really costs to heat a home in the UK with a heat pump appeared first on Carbon Brief.
Factcheck: What it really costs to heat a home in the UK with a heat pump
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Lena Luig is the head of the International Agricultural Policy Division at the Heinrich Böll Foundation, a member of the Global Alliance for the Future of Food. Anna Lappé is the Executive Director of the Global Alliance for the Future of Food.
As toxic clouds loom over Tehran and Beirut from the US and Israel’s bombardment of oil depots and civilian infrastructure in the region’s ongoing war, the world is once again witnessing the not-so-subtle connections between conflict, hunger, food insecurity and the vulnerability of global food systems dependent on fossil fuels, dominated by a few powerful countries and corporations.
The conflict in Iran is having a huge impact on the world’s fertilizer supply. The Strait of Hormuz is a critical trade route in the region for nearly half of the global supply of urea, the main synthetic fertilizer derived from natural gas through the conversion of ammonia.
With the Strait impacted by Iran’s blockades, prices of urea have shot up by 35% since the war started, just as planting season starts in many parts of the world, putting millions of farmers and consumers at risk of increasing production costs and food price spikes, resulting in food insecurity, particularly for low-income households. The World Food Programme has projected that an extra 45 million people would be pushed into acute hunger because of rises in food, oil and shipping costs, if the war continues until June.
Pesticides and synthetic fertilizer leave system fragile
On the face of it, this looks like a supply chain issue, but at the core of this crisis lies a truth about many of our food systems around the world: the instability and injustice in the very design of systems so reliant on these fossil fuel inputs for our food.
At the Global Alliance, a strategic alliance of philanthropic foundations working to transform food systems, we have been documenting the fossil fuel-food nexus, raising alarm about the fragility of a system propped up by fossil fuels, with 15% of annual fossil fuel use going into food systems, in part because of high-cost, fossil fuel-based inputs like pesticides and synthetic fertilizer. The Heinrich Böll Foundation has also been flagging this threat consistently, most recently in the Pesticide Atlas and Soil Atlas compendia.
We’ve seen this before: Russia’s invasion of Ukraine in 2022 sparked global disruptions in fertilizer supply and food price volatility. As the conflict worsened, fertilizer prices spiked – as much from input companies capitalizing on the crisis for speculation as from real cost increases from production and transport – triggering a food price crisis around the world.
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Since then, fertilizer industry profit margins have continued to soar. In 2022, the largest nine fertilizer producers increased their profit margins by more than 35% compared to the year before—when fertilizer prices were already high. As Lena Bassermann and Dr. Gideon Tups underscore in the Heinrich Böll Foundation’s Soil Atlas, the global dependencies of nitrogen fertilizer impacted economies around the world, especially state budgets in already indebted and import-dependent economies, as well as farmers across Africa.
Learning lessons from the war in Ukraine, many countries invested heavily in renewable energy and/or increased domestic oil production as a way to decrease dependency on foreign fossil fuels. But few took the same approach to reimagining domestic food systems and their food sovereignty.
Agroecology as an alternative
There is another way. Governments can adopt policy frameworks to encourage reductions in synthetic fertilizer and pesticide use, especially in regions that currently massively overuse nitrogen fertilizer. At the African Union fertilizer and Soil Health Summit in 2024, African leaders at least agreed that organic fertilizers should be subsidized as well, not only mineral fertilizers, but we can go farther in actively promoting agricultural pathways that reduce fossil fuel dependency.
In 2024, the Global Alliance organized dozens of philanthropies to call for a tenfold increase in investments to help farmers transition from fossil fuel dependency towards agroecological approaches that prioritize livelihoods, health, climate, and biodiversity.
In our research, we detail the huge opportunity to repurpose harmful subsidies currently supporting inputs like synthetic fertilizer and pesticides towards locally-sourced bio-inputs and biofertilizer production. We know this works: There are powerful stories of hope and change from those who have made this transition, despite only receiving a fraction of the financing that industrial agriculture receives, with evidence of benefits from stable incomes and livelihoods to better health and climate outcomes.
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Inspiring examples abound: G-BIACK in Kenya is training farmers how to produce their own high-quality compost; start-ups like the Evola Company in Cambodia are producing both nutrient-rich organic fertilizer and protein-rich animal feed with black soldier fly farming; Sabon Sake in Ghana is enriching sugarcane bagasse – usually organic waste – with microbial agents and earthworms to turn it into a rich vermicompost.
These efforts, grounded in ecosystems and tapping nature for soil fertility and to manage pest pressures, are just some of the countless examples around the world, tapping the skill and knowledge of millions of farmers. On a national and global policy level, the Agroecology Coalition, with 480+ members, including governments, civil society organizations, academic institutions, and philanthropic foundations, is supporting a transition toward agroecology, working with natural systems to produce abundant food, boost biodiversity, and foster community well-being.
Fertilizer industry spins “clean” products
We must also inoculate ourselves from the fertilizer industry’s public relations spin, which includes promoting the promise that their products can be produced without heavy reliance on fossil fuels. Despite experts debunking the viability of what the industry has dubbed “green hydrogen” or “green or clean ammonia”, the sector still promotes this narrative, arguing that these are produced with resource-intensive renewable energy or Carbon Capture and Storage (CCS), a costly and unreliable technology for reducing emissions.
As we mourn this conflict’s senseless destruction and death, including hundreds of children, we also recognize that peace cannot mean a return to business-as-usual. We need to upend the systems that allow the richest and most powerful to have dominion over so much.
This includes fighting for a food system that is based on genuine sovereignty and justice, free from dependency on fossil fuels, one that honors natural systems and puts power into the hands of communities and food producers themselves.
The post Middle East war is another wake-up call for fossil fuel-reliant food systems appeared first on Climate Home News.
Middle East war is another wake-up call for fossil fuel-reliant food systems
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