For most UK homes, heating and hot water swallow more energy than everything electrical put together. Gas central heating, an oil boiler or electric heating is usually the single largest line on the bill, which is exactly why it is where the biggest savings hide. This page is the overview. It sets out what your heating actually costs, the order to tackle savings in so you spend the least for the most, and links to the deeper guides on each step.
The short answer. Heating is the largest energy cost in most homes, often well over half the annual bill. The cheapest savings come first and cost nothing: turn the thermostat down a degree and time the heating to when you are home. Next, stop heat escaping with draught-proofing and insulation. Last, fine-tune the boiler. Done in that order you cut the bill hard before spending a penny on kit.
Why heating dominates the bill
A typical household on the Ofgem cap pays around £1,663 a year for gas and electricity combined. In a gas-heated home, the gas portion is mostly space heating and hot water, and that alone often runs to more than half the total. Heating a house is simply energy-hungry work: you are warming the air, the walls, the floors and everything in the rooms, and a chunk of that heat leaks straight back outside through the fabric of the building.
The good news is that the same fact that makes heating expensive makes it the best place to save. A 10 percent cut on a £900 heating bill is worth far more than a 10 percent cut on the lighting. So before fretting over standby plugs, get the heating right. The rest of the site covers the small electrical wins, but this is where the real money is.
Gas costs about 7.33p per kWh and electricity about 26.11p per kWh, so how you heat matters as much as how much. If you heat with electricity, every saving below is worth roughly three and a half times more in cash terms. If you heat with electric storage heaters, our guide to storage heaters covers getting the most from cheap-rate charging, and the wider electricity overview covers the non-heating side.
Turn it down and time it: the free wins
The thermostat is the cheapest energy-saving tool in the house because it costs nothing and controls the biggest bill. Two habits do most of the work.
- Drop the temperature a degree. Turning a thermostat down by one degree trims a noticeable slice off a heating bill and is barely perceptible with a jumper on. Set it to the lowest temperature that is genuinely comfortable, not the highest you can afford. Our thermostat settings guide and what temperature should I set my thermostat cover the detail.
- Time it to your life. There is no sense heating an empty or sleeping house to daytime warmth. A programmer or smart thermostat brings the heat up shortly before you get up and home, then lets it drop when you are out or in bed.
- Heat where you live. Use thermostatic radiator valves to turn unused rooms down, so you are not heating spare bedrooms to living-room warmth, weighed up in is it cheaper to heat one room or the whole house. If you reach for a plug-in heater to warm that one room, our guide to portable electric heater running costs shows when spot-heating actually saves and when it quietly costs more.
One persistent myth is that leaving the heating on low all day is cheaper than heating to schedule. For almost everyone it is not. A well-timed system that heats when you are home and cools when you are out uses less than one trickling away around the clock. Our piece on leaving the heating on all day works through the exceptions.
Stop the heat escaping
Heat you have paid for leaking straight back outside is the real waste, and plugging the leaks makes a cold house feel warmer at once. There is a clear order here too, from cheap and quick to costly but transformative.
Draught-proofing doors, windows, letterboxes and unused chimneys is cheap, fast and often pays back in a single winter. Heavier curtains and tucking reflectors behind radiators on outside walls cost a few pounds and help on the same day.
Insulation is the higher-value, higher-cost step. Loft insulation comes first because it is cheap per unit of heat saved and easy to fit; see loft insulation. Then walls, with cavity wall insulation the bigger win where your house has a suitable cavity, and solid wall insulation for older homes. Underfloor insulation and double or secondary glazing finish the job. These cost more up front but pay back over a few winters and then save for decades.
Get more from the boiler
A few free or cheap tweaks make a gas boiler squeeze more warmth from the same gas. None of them needs an engineer for the basics.
- Bleed the radiators. Air trapped in a radiator stops the top heating up, so the boiler runs longer to do the same job. Our how to bleed radiators guide takes ten minutes to follow.
- Keep radiators clear. A sofa or a long curtain over a radiator soaks up the heat before it reaches the room.
- Lower the flow temperature. On a condensing combi, turning the flow temperature down to around 55C or 60C lets the boiler actually condense, which is where its efficiency comes from. This single change can knock several percent off gas use for nothing. The mechanics are in how condensing boilers work.
If you are weighing a bigger change, a heat pump is the long-term low-carbon route, though the running-cost case depends on your tariff and insulation. See heat pumps explained and heat pump running cost versus a gas boiler before committing.
The order of value, with rough costs
Do the cheap things first. The table below puts the main moves in rough order of bang for buck, from free habits to capital jobs. Exact figures vary enormously by house, so treat these as a guide to sequence, not a promise.
| Step | Rough cost | Typical annual gas saving |
|---|---|---|
| Turn thermostat down 1C | Free | £60 to £100 |
| Time the heating to occupancy | Free to £150 (smart stat) | £50 to £150 |
| Zone with radiator valves | £10 to £20 per valve | £30 to £80 |
| Draught-proofing | £20 to £100 DIY | £40 to £60 |
| Lower boiler flow temperature | Free | £50 to £110 |
| Loft insulation (top up) | £300 to £600 | £150 to £250 |
| Cavity wall insulation | £500 to £1,500 | £150 to £300 |
At 7.33p per kWh gas, Ofgem cap July to September 2026. Savings are typical ranges for a three-bed house; your figures depend on insulation, boiler and how cold the winter is. Worked examples; check your own bills.
The pattern is the point. The free changes near the top can be done this week and cost nothing. Only once those are in place does spending on insulation make sense, and grants under the ECO scheme may cover some of it.
Where to go next
This page is the map. For the specific jobs, follow the guides that matter to your home:
- Setting the heating: thermostat settings and radiator valves and zoning.
- Stopping leaks: draught-proofing, loft insulation and curtains for warmth.
- The boiler: boiler flow temperature and how to bleed radiators.
- Hot water, the other big gas user: hot water savings and cylinder jacket and pipe lagging.
- Renting and limited on changes: saving energy when renting.
For a seasonal once-over, the winter energy checklist ties the heating jobs together. Get the free wins done first, then work down the list as budget allows.