There's an evening each autumn when someone in the house finally gives in and turns the heating on. The radiators tick as they warm, the windows mist a little, and for the next six months the boiler quietly becomes one of the busiest machines in the home.
It's also, for most British households, one of the largest parts of their carbon footprint. The good news is that the choices which matter most are fairly few, and several of them cost nothing at all.
The short answer: to heat your home with less carbon, keep more of the heat you already pay for (insulation and draught proofing), use your current system more efficiently (especially a lower boiler flow temperature), and, when the time is right, change how your heat is made, most often by moving from a gas or oil boiler to a well designed heat pump. Grants of up to £7,500 are available in England and Wales, and up to £9,000 for some homes off the gas grid until March 2027.
"Insulation reduces how much heat a home needs; changing the heat source changes how much carbon every remaining unit of that heat carries."
Table of contents
Why heating matters so much for household carbon Keep, use, make: a simple way to think about it Keep: hold on to the heat you've paid for Use: get more from the system you already have Make: change how your heat is produced What the numbers say The honest caveats Other low carbon options Help with the cost CNB's view: fabric first, not fabric forever Carbon Neutral Britain™
Why heating matters so much for household carbon
Burning gas, oil and other fuels in buildings, mostly for heating and cooking, accounted for 22% of the UK's greenhouse gas emissions in 2024, and two thirds of that came from homes. In other words, the fuel burned in our homes produces roughly one in every seven tonnes of the country's emissions. That figure doesn't even include electricity used for heating, which the government counts under power stations instead (DESNZ, 2024 UK greenhouse gas emissions final figures).
There's real progress to acknowledge. Emissions from homes fell by 32% between 1990 and 2024, even as the number of households grew, partly because far fewer of us now heat with coal. But they still rose by 4% in 2024 compared with 2023, and the same government statistics note that year to year changes are heavily shaped by how cold the winter is (DESNZ). The weather still has a strong say in our footprint, and that's precisely what better heating is meant to change.
We touched on this in Ten Things Individuals Can Do About Climate Change, where heating sits among the actions that matter most. This guide goes a level deeper.
Keep, use, make: a simple way to think about it
Heating advice often arrives as a long list of tips with no sense of which ones matter. We find it more useful to ask three questions, in this order of ease, though not necessarily in this order of impact:
Keep: how much of the heat you produce stays in the house?
Use: how efficiently does your current system turn fuel into warmth?
Make: how much carbon is released in producing that heat in the first place?
The first two cost little and help almost every home this winter. The third is where the largest single reductions are found, but it's a bigger decision that deserves proper thought. Most households will work on all three over a number of years, and that's fine. The point is to know what each one can and can't do.
Keep: hold on to the heat you've paid for
Every unit of heat that escapes through a roof, a gap under a door or an uninsulated wall has to be replaced, and if it's replaced by burning gas, that's carbon released for warmth nobody felt.
The government's Warm Homes Plan describes fabric insulation, installed with appropriate ventilation, as "a cornerstone of energy efficiency", noting that it also helps reduce damp and mould and makes homes more comfortable (GOV.UK, Warm Homes Plan). In practice, the usual priorities are:
Loft insulation, often the simplest and most cost effective place to start.
Cavity wall insulation, if your walls have a cavity and it's suitable.
Draught proofing around doors, windows, letterboxes, loft hatches and unused chimneys.
Better glazing or heavy curtains, which help most in rooms that feel cold even when the heating is on.
One honest caveat. The same plan acknowledges that some measures, particularly solid wall insulation, "have become less viable in recent years following supply chain cost increases" (GOV.UK, Warm Homes Plan). If you live in an older solid walled home, insulation still helps, but it may not be the whole answer, and it shouldn't become a reason to put off the bigger decision indefinitely. We come back to this below.
Use: get more from the system you already have
For the millions of homes still heated by a gas boiler, the quickest carbon saving is often a setting change rather than a purchase. The most useful one is the flow temperature: the temperature of the water your boiler sends to the radiators. Many boilers are set higher than they need to be, which can stop them running in their more efficient condensing mode.
Citizens Advice explains that if you have a combi boiler with radiators, you can try setting the flow temperature to 60°C, and it won't change the temperature of your hot tap water. If you have a system or regular boiler with a hot water cylinder, it should be no lower than 65°C, to stop harmful bacteria growing in the cylinder. Your home may take a little longer to warm up, so it can help to set the heating to come on earlier. If you have a heat pump, leave the flow temperature alone unless your installer says otherwise (Citizens Advice).
Smaller habits add up too. Set the timer around when you're actually home, use thermostatic radiator valves to turn down rooms you aren't using, bleed radiators that are cold at the top, and get the boiler serviced so it keeps running safely and as designed.
A gentle but important word on comfort. Using heat well is not the same as going without it. A cold, damp home is bad for health, particularly for older people, young children and anyone with a health condition, and it is not a climate win. The aim is to waste less heat, not to feel colder.
Make: change how your heat is produced
This is where the largest reductions sit, because it changes the source of the carbon rather than the amount of heat. For most homes, that means a heat pump, which moves heat from the outside air, the ground or water into your home, using electricity to do it. Because it moves heat rather than creating it by burning fuel, it can deliver more heat than the electricity it uses.
The most useful evidence comes from real British homes rather than laboratory tests. The government funded Electrification of Heat Demonstration Project installed 742 heat pumps in a wide range of existing homes, most of them previously heated by gas, and found that heat pumps could be installed successfully in every type of property it tested ( Energy Systems Catapult, Electrification of Heat). Across a full year, the median air source heat pump delivered 2.8 units of heat for every unit of electricity, and still managed 2.44 on the coldest days of the year ( Energy Systems Catapult).
The government's Warm Homes Plan states plainly that "heat pumps will be the best and cheapest form of electrified heating for the majority of our homes" ( GOV.UK, Warm Homes Plan).
What the numbers say
Using the government's own 2026 carbon factors, a gas boiler running at 85% efficiency releases about 214 g of CO2e for every kWh of heat delivered to your radiators. An oil boiler at the same efficiency releases about 290 g, roughly 35% more. A typical air source heat pump, with an efficiency of 2.8, releases about 51 g: around 76% less than gas. Even a lower performing heat pump (2.53) comes out about 73% lower, and a better performing one (3.09) about 78% lower.
These figures use the UK Government greenhouse gas conversion factors 2026: natural gas at 0.18231 kg CO2e per kWh, burning oil at 0.24677 kg CO2e per kWh (both gross calorific value), and UK electricity at 0.14395 kg CO2e per kWh including transmission and distribution losses. Heat pump efficiencies are the median and middle range of air source systems in the Electrification of Heat project's interim performance data. The 85% boiler efficiency is our own assumption for a typical boiler in everyday use; a well set up condensing boiler may do better, an older one worse.
To put that in household terms, Ofgem now treats 9,500 kWh of gas a year as typical for a medium user (Ofgem). Burning that releases about 1.7 tonnes of CO2e. Delivering the same warmth with a typical heat pump would release roughly 0.4 tonnes on today's grid. That's a rough illustration rather than a prediction for any particular home, because gas figures include cooking and hot water, and every house is different.
The gap is also likely to widen. Britain's electricity is getting cleaner, as we explored in our piece on the UK's clean electricity milestone, so a heat pump installed today should become lower carbon over its lifetime, while a gas boiler stays more or less where it is.
The honest caveats
A heat pump is not automatically a good heat pump. A government report for the Committee on Fuel Poverty found a wide gap between the best and worst performing systems: homes on a separate monitoring platform of high performing installations averaged an efficiency of 3.9, against 2.8 in the Electrification of Heat trial (GOV.UK, Committee on Fuel Poverty). Design, sizing, radiators and installation quality matter enormously, so it's worth choosing an accredited installer and asking how they'll design the system for your home.
Running costs deserve the same honesty. The same report found that at an efficiency of 2.8, a heat pump was cheaper to run than oil, LPG, direct electric and storage heaters, but more expensive than a mains gas boiler at current prices (GOV.UK, Committee on Fuel Poverty). A well designed, efficient system and a suitable electricity tariff can change that picture, but it would be wrong to promise lower bills in every home.
Other low carbon options
Heat networks pipe heat to many homes from a shared source. The government aims to more than double the share of heat demand they meet in England by 2035 ( GOV.UK, Warm Homes Plan), and since January 2026, heat network suppliers have had to meet consumer protection rules overseen by Ofgem (Ofgem). Some draw on surprising sources, including the warm water in old coal mines.
Air to air heat pumps heat rooms directly and can also cool them in summer, which brings its own considerations, as we looked at in How Green Is Air Conditioning? Heat batteries store heat, often charged with cheaper off peak electricity, and we covered how they work in our article on heat batteries. The government has confirmed it will begin providing Boiler Upgrade Scheme grants for both ( GOV.UK, Warm Homes Plan).
Hydrogen boilers are sometimes mentioned as an alternative, but the government's current position is that hydrogen "is not yet a proven technology for home heating", and that any role "would come later and likely be limited" (GOV.UK, Hydrogen heating overview). It isn't something to wait for.
Help with the cost
The support available depends on where you live and whether you own or rent. In England and Wales, the Boiler Upgrade Scheme offers £7,500 off an air to water or ground source heat pump, and £2,500 off an air to air heat pump. Homes off the gas grid replacing oil or LPG heating can receive £9,000 for applications made between 21 July 2026 and 31 March 2027. The grant is paid to your installer and taken off your quote ( Ofgem, Boiler Upgrade Scheme guidance).
In Scotland, the Home Energy Scotland Grant and Loan offers up to £7,500 in grant funding for heat pumps and heat network connections, with a further £7,500 available as an optional interest free loan, plus an uplift for rural and island homes (Home Energy Scotland). The Warm Homes Plan also sets out new low and zero interest loans for home upgrades, to be rolled out in phases, with eligibility details still to come ( GOV.UK, Warm Homes Plan).
If you rent privately in England or Wales, your landlord will need the property to meet EPC C by 1 October 2030, unless an exemption applies (GOV.UK, government response). If your home is cold or expensive to heat, it's worth raising now. And under the Future Homes Standard, new homes in England will need low carbon heating such as heat pumps or heat networks, with the standard coming into force on 24 March 2027 (GOV.UK).
CNB's view: fabric first, not fabric forever
"Fabric first" is good advice. Keeping heat in makes a home more comfortable, reduces bills and helps any heating system work better, including a heat pump.
But it can quietly become "fabric only", or "fabric forever". Our worked example shows why that matters. Insulation reduces how much heat a home needs; changing the heat source changes how much carbon every remaining unit of that heat carries. For many homes, especially older ones where solid wall insulation is expensive, the largest reduction comes from the second step. The evidence from real installations suggests that good design and installation can make heat pumps work well across a wide range of British homes ( Energy Systems Catapult), so a home doesn't need to be perfect before it's ready.
Our view is that keeping, using and making heat better are not a queue. They're three jobs that can run alongside each other, at whatever pace a household can manage.
The same thinking applies to the emissions that remain. Most homes will still produce some carbon from heating for years, while boilers reach the end of their lives and plans come together. Reducing those emissions and funding verified climate action at the same time is not an either or choice. Supporting projects such as solar water heaters in India, which help households avoid burning fossil fuels for hot water, can sit alongside the changes you make at home. It isn't a substitute for them, and it's worth knowing the difference: projects like this avoid emissions, while carbon removal projects draw carbon already in the atmosphere back out of it. If you'd like to take that step, our individual carbon neutral plans are built around verified projects with registry evidence you can check.
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What is the single biggest change I can make to heat my home with less carbon?
For most homes heated by gas or oil, it's replacing the boiler with a well designed heat pump. On the government's 2026 carbon factors, a typical air source heat pump produces roughly three quarters less carbon per unit of heat than a gas boiler ( UK Government conversion factors 2026). If that isn't possible yet, lowering your boiler's flow temperature and improving insulation are the best places to start.
Do heat pumps work in older or poorly insulated homes?
The Electrification of Heat project installed heat pumps successfully in every type of property it tested, including older homes ( Energy Systems Catapult). Insulation still helps, but correct sizing, radiator design and installation quality are just as important. A good installer will carry out a heat loss assessment for your home.
Will turning my boiler flow temperature down make my home colder?
It shouldn't make the rooms colder, but your home may take a little longer to warm up, so set your heating to come on earlier. Keep system and regular boilers with a hot water cylinder at 65°C or above (Citizens Advice). If the house struggles to reach a comfortable temperature, turn it back up.
Should I replace a working gas boiler now?
Not necessarily. Replacing a system that still works brings its own costs and resources. Many households plan the switch for when the boiler is nearing the end of its life, which avoids a rushed decision in the middle of winter. In the meantime, getting quotes, checking grant eligibility and improving insulation means you're ready when the time comes.
A quieter kind of progress
Heating rarely feels like climate action. It's a dial on a wall, a timer, a radiator that needs bleeding. But it's one of the few parts of a household's footprint where the evidence is clear, the support is real, and the changes, once made, keep working every winter without anyone having to think about them.
That evening when the heating first comes on will keep arriving each autumn. What can change is how much carbon arrives with it.
