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Is it cheaper to leave central heating on all day?

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UKPublished 6 October 2026 · Written by BuyMeWhiskey Editorial Team · How we check facts

For a gas boiler, usually no: keeping central heating on all day generally uses more energy and costs more than heating the home when you need it. Heat pumps are different and can work better when run steadily for longer periods.

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Check Ofgem's current energy-price-cap rates, then compare them with your own tariff and usage rather than the headline annual cap.

Check Ofgem's current energy rates

Why the boiler advice is usually “heat when needed”

A gas boiler does not become cheaper just because it runs gently for longer. Energy Saving Trust's September 2026 guidance says that, for a boiler, leaving the heating on all the time will use more energy and cost more than running it when needed.

The reason is simple: while the home is being maintained at a warmer temperature, it continues to lose heat to the outside. The longer you keep it warm, the more energy the system must put back in. Good controls reduce waste by deciding when the boiler should fire and what temperature the room should reach.

Heat pumps are the important exception

Heat pumps work differently. Energy Saving Trust says heat pumps can save money by being left running all day, because they are designed to provide heat steadily at a lower level rather than behave like a gas boiler that repeatedly heats a room to a set point.

That means advice copied from a gas-boiler household may be wrong for a heat-pump home. Your system, tariff and controls matter.

Your thermostat sets the comfort target

Energy Saving Trust currently recommends setting the room thermostat between 18°C and 21°C to balance comfort and savings. It also says that lowering a thermostat from 22°C to 21°C could save around £120 a year in Great Britain, although that saving depends on the home and energy use.

Do not treat that estimate as a guaranteed saving for your property. A thermostat is a control, not a timer: it allows the system to stop heating once the target temperature is reached. A sensible schedule and a sensible target temperature work together.

What the October 2026 price cap actually says

Ofgem's current cap for 1 October to 31 December 2026 is based on average rates for households in England, Scotland and Wales paying by Direct Debit. The published average electricity unit rate is 26.32p per kWh, with a daily electricity standing charge of 54.83p. The corresponding gas unit rate is 7.97p per kWh, with a daily gas standing charge of 29.68p.

The cap is not a fixed annual bill. Your actual cost depends on the amount of energy you use, your region, how you pay and the type of meter. Ofgem updates the cap every three months, so a calculation made today should not be treated as a permanent price.

Timers and smart controls help because they match use to occupancy

For a boiler, scheduling the heating around the times you are actually at home can reduce unnecessary running time. Energy Saving Trust suggests a simple pattern of bringing the heating on around half an hour before you get up and switching it off around half an hour before bed, with adjustments for your household's routine.

Smart thermostats can take this further by allowing temperature schedules and remote control. The benefit is not that the app makes energy cheap; it is that better control can stop the system heating an empty home.

Heat the rooms you use

Thermostatic radiator valves allow room-by-room control, so a hallway or spare room does not have to be heated exactly like a living room. Ofgem guidance also describes timers, room thermostats and radiator controls as core heating controls in relevant energy-efficiency measures.

The same principle applies to doors and draughts. A home that loses heat quickly will need more energy whatever schedule you choose. Heating controls are useful, but they cannot compensate for every insulation problem.

Does turning heating on and off use extra energy that cancels the saving?

For a gas boiler, this is a common misunderstanding. Energy Saving Trust's current advice is that turning the boiler on when needed is more energy efficient than leaving it on all the time. The boiler will cycle as needed to maintain the thermostat set point, so the important question is how much heat the home needs over the period.

The exact answer can differ for specialised systems, underfloor heating arrangements and heat pumps. Those systems should be controlled according to their design rather than a generic “boiler” rule.

The practical rule

If you have a conventional gas boiler, use a timer or smart control so the home is heated when you need it. Use the lowest comfortable thermostat setting, keep radiators and controls working properly, and check your actual unit rates.

If you have a heat pump, take the opposite lesson seriously: steady operation can be more efficient. The right schedule is the one matched to the heating technology, your home's heat loss and the temperature you actually need.

Illustrative one-day gas cost using Ofgem's 7.97p/kWh rate

Worked example

Illustrative gas-use comparison: suppose, purely for illustration, that a home's boiler system uses 5 kWh of gas in each hour when it is actively heating. Using Ofgem's average gas unit rate of 7.97p per kWh for 1 October to 31 December 2026:

Four hours of active heating: 5 kWh × 4 = 20 kWh; 20 × 7.97p = 159.4p, or £1.594.
Ten hours of active heating: 5 kWh × 10 = 50 kWh; 50 × 7.97p = 398.5p, or £3.985.
Illustrative difference: £3.985 − £1.594 = £2.391 for that day's gas use.

This is illustrative, not a household bill forecast. Real boilers cycle on and off, homes lose heat at different rates, and your actual tariff may differ from Ofgem's average cap rate. The example simply shows why “on longer” can mean “more energy used” even when the thermostat is controlling the room temperature.

Is it cheaper to keep the heating on low all day?#

For a gas boiler, generally no. Energy Saving Trust's current guidance says keeping a boiler running all the time uses more energy and costs more than running it when you need it. Heat pumps are different and can benefit from longer, steadier operation.

What temperature should I set my heating to?#

Energy Saving Trust recommends a room thermostat setting between 18°C and 21°C for comfort and savings. The best setting for your household can be different, especially if someone is vulnerable to cold. Turning the thermostat higher does not make the home heat to temperature faster; it raises the target.

Does turning the boiler off and on cost more?#

Not usually for a conventional gas boiler. The current Energy Saving Trust guidance says it is more efficient to have the boiler come on when you need it than to keep it on continuously. The exception is that heating technologies such as heat pumps should be controlled differently.

What are Ofgem gas prices right now in 2026?#

For 1 October to 31 December 2026, Ofgem's average gas unit rate for a Direct Debit customer across England, Scotland and Wales is 7.97p per kWh, with a 29.68p daily standing charge. Your actual tariff can differ by region, payment method and meter.

Should I leave heating on when I go to work?#

For a gas boiler, usually no. Heating an empty home wastes energy unless you need a low background temperature for a particular reason. A timer or smart thermostat can switch heating on before you return instead of leaving it running all day.

Does a smart thermostat automatically save money?#

It can help, but the saving comes from better control rather than from the device itself. Smart controls can schedule heating, reduce heating when you are out and allow remote adjustments. The biggest gains still depend on the temperature you choose and how much heat the home loses.

Why is a heat pump different from a gas boiler?#

A heat pump is designed to deliver heat more steadily and efficiently at lower temperatures. Energy Saving Trust says heat pumps can save money by being left on all day, unlike a gas boiler, where continuous operation generally uses more energy. Always follow the controls and installer guidance for the specific system.

Keep reading

Next question →Can I cancel a new energy tariff during the cooling-off period?

Sources

Figures were checked against these sources before publication. If a rule changes, we update the page and show the new date.

General information, not personal financial advice. Rules depend on your circumstances; check the official source or speak to a regulated adviser before acting.