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
Drought and heatwaves occurring together – known as “compound” events – have “surged” across the world since the early 2000s, a new study shows.
Compound drought and heat events (CDHEs) can have devastating effects, creating the ideal conditions for intense wildfires, such as Australia’s “Black Summer” of 2019-20 where bushfires burned 24m hectares and killed 33 people.
The research, published in Science Advances, finds that the increase in CDHEs is predominantly being driven by events that start with a heatwave.
The global area affected by such “heatwave-led” compound events has more than doubled between 1980-2001 and 2002-23, the study says.
The rapid increase in these events over the last 23 years cannot be explained solely by global warming, the authors note.
Since the late 1990s, feedbacks between the land and the atmosphere have become stronger, making heatwaves more likely to trigger drought conditions, they explain.
One of the study authors tells Carbon Brief that societies must pay greater attention to compound events, which can “cause severe impacts on ecosystems, agriculture and society”.
Compound events
CDHEs are extreme weather events where drought and heatwave conditions occur simultaneously – or shortly after each other – in the same region.
These events are often triggered by large-scale weather patterns, such as “blocking” highs, which can produce “prolonged” hot and dry conditions, according to the study.
Prof Sang-Wook Yeh is one of the study authors and a professor at the Ewha Womans University in South Korea. He tells Carbon Brief:
“When heatwaves and droughts occur together, the two hazards reinforce each other through land-atmosphere interactions. This amplifies surface heating and soil moisture deficits, making compound events more intense and damaging than single hazards.”
CDHEs can begin with either a heatwave or a drought.
The sequence of these extremes is important, the study says, as they have different drivers and impacts.
For example, in a CDHE where the heatwave was the precursor, increased direct sunshine causes more moisture loss from soils and plants, leading to a drought.
Conversely, in an event where the drought was the precursor, the lack of soil moisture means that less of the sun’s energy goes into evaporation and more goes into warming the Earth’s surface. This produces favourable conditions for heatwaves.
The study shows that the majority of CDHEs globally start out as a drought.
In recent years, there has been increasing focus on these events due to the devastating impact they have on agriculture, ecosystems and public health.
In Russia in the summer of 2010, a compound drought-heatwave event – and the associated wildfires – caused the death of nearly 55,000 people, the study notes.
The record-breaking Pacific north-west “heat dome” in 2021 triggered extreme drought conditions that caused “significant declines” in wheat yields, as well as in barley, canola and fruit production in British Columbia and Alberta, Canada, says the study.
Increasing events
To assess how CDHEs are changing, the researchers use daily reanalysis data to identify droughts and heatwaves events. (Reanalysis data combines past observations with climate models to create a historical climate record.) Then, using an algorithm, they analyse how these events overlap in both time and space.
The study covers the period from 1980 to 2023 and the world’s land surface, excluding polar regions where CDHEs are rare.
The research finds that the area of land affected by CDHEs has “increased substantially” since the early 2000s.
Heatwave-led events have been the main contributor to this increase, the study says, with their spatial extent rising 110% between 1980-2001 and 2002-23, compared to a 59% increase for drought-led events.
The map below shows the global distribution of CDHEs over 1980-2023. The charts show the percentage of the land surface affected by a heatwave-led CDHE (red) or a drought-led CDHE (yellow) in a given year (left) and relative increase in each CDHE type (right).
The study finds that CDHEs have occurred most frequently in northern South America, the southern US, eastern Europe, central Africa and south Asia.
Threshold passed
The authors explain that the increase in heatwave-led CDHEs is related to rising global temperatures, but that this does not tell the whole story.
In the earlier 22-year period of 1980-2001, the study finds that the spatial extent of heatwave-led CDHEs rises by 1.6% per 1C of global temperature rise. For the more-recent period of 2022-23, this increases “nearly eightfold” to 13.1%.
The change suggests that the rapid increase in the heatwave-led CDHEs occurred after the global average temperature “surpasse[d] a certain temperature threshold”, the paper says.
This threshold is an absolute global average temperature of 14.3C, the authors estimate (based on an 11-year average), which the world passed around the year 2000.
Investigating the recent surge in heatwave-leading CDHEs further, the researchers find a “regime shift” in land-atmosphere dynamics “toward a persistently intensified state after the late 1990s”.
In other words, the way that drier soils drive higher surface temperatures, and vice versa, is becoming stronger, resulting in more heatwave-led compound events.
Daily data
The research has some advantages over other previous studies, Yeh says. For instance, the new work uses daily estimations of CDHEs, compared to monthly data used in past research. This is “important for capturing the detailed occurrence” of these events, says Yeh.
He adds that another advantage of their study is that it distinguishes the sequence of droughts and heatwaves, which allows them to “better understand the differences” in the characteristics of CDHEs.
Dr Meryem Tanarhte is a climate scientist at the University Hassan II in Morocco, and Dr Ruth Cerezo Mota is a climatologist and a researcher at the National Autonomous University of Mexico. Both scientists, who were not involved in the study, agree that the daily estimations give a clearer picture of how CDHEs are changing.
Cerezo-Mota adds that another major contribution of the study is its global focus. She tells Carbon Brief that in some regions, such as Mexico and Africa, there is a lack of studies on CDHEs:
“Not because the events do not occur, but perhaps because [these regions] do not have all the data or the expertise to do so.”
However, she notes that the reanalysis data used by the study does have limitations with how it represents rainfall in some parts of the world.
Compound impacts
The study notes that if CDHEs continue to intensify – particularly events where heatwaves are the precursors – they could drive declining crop productivity, increased wildfire frequency and severe public health crises.
These impacts could be “much more rapid and severe as global warming continues”, Yeh tells Carbon Brief.
Tanarhte notes that these events can be forecasted up to 10 days ahead in many regions. Furthermore, she says, the strongest impacts can be prevented “through preparedness and adaptation”, including through “water management for agriculture, heatwave mitigation measures and wildfire mitigation”.
The study recommends reassessing current risk management strategies for these compound events. It also suggests incorporating the sequences of drought and heatwaves into compound event analysis frameworks “to enhance climate risk management”.
Cerezo-Mota says that it is clear that the world needs to be prepared for the increased occurrence of these events. She tells Carbon Brief:
“These [risk assessments and strategies] need to be carried out at the local level to understand the complexities of each region.”
The post Heatwaves driving recent ‘surge’ in compound drought and heat extremes appeared first on Carbon Brief.
Heatwaves driving recent ‘surge’ in compound drought and heat extremes
Greenhouse Gases
DeBriefed 6 March 2026: Iran energy crisis | China climate plan | Bristol’s ‘pioneering’ wind turbine
Welcome to Carbon Brief’s DeBriefed.
An essential guide to the week’s key developments relating to climate change.
This week
Energy crisis
ENERGY SPIKE: US-Israeli attacks on Iran and subsequent counterattacks across the Middle East have sent energy prices “soaring”, according to Reuters. The newswire reported that the region “accounts for just under a third of global oil production and almost a fifth of gas”. The Guardian noted that shipping traffic through the strait of Hormuz, which normally ferries 20% of the world’s oil, “all but ground to a halt”. The Financial Times reported that attacks by Iran on Middle East energy facilities – notably in Qatar – triggered the “biggest rise in gas prices since Russia’s full-scale invasion of Ukraine”.
‘RISK’ AND ‘BENEFITS’: Bloomberg reported on increases in diesel prices in Europe and the US, speculating that rising fuel costs could be “a risk for president Donald Trump”. US gas producers are “poised to benefit from the big disruption in global supply”, according to CNBC. Indian government sources told the Economic Times that Russia is prepared to “fulfil India’s energy demands”. China Daily quoted experts who said “China’s energy security remains fundamentally unshaken”, thanks to “emergency stockpiles and a wide array of import channels”.
‘ESSENTIAL’ RENEWABLES: Energy analysts said governments should cut their fossil-fuel reliance by investing in renewables, “rather than just seeking non-Gulf oil and gas suppliers”, reported Climate Home News. This message was echoed by UK business secretary Peter Kyle, who said “doubling down on renewables” was “essential” amid “regional instability”, according to the Daily Telegraph.
China’s climate plan
PEAK COAL?: China has set out its next “five-year plan” at the annual “