Is It Cheaper to Leave Heating On Low All Day or Turn It Off?

This is the most-searched heating question in the UK every winter - and there's a clear, definitive answer. Turn it off and use a timer. Leaving it on low all day costs approximately £200 - 280 more per year. Here's the evidence and the exact settings that save the most.

The "leave it on low" myth - busted

The argument for leaving heating on all day goes: "It takes more energy to reheat a cold house than to maintain a warm one."

This sounds logical. It's wrong - and the Energy Saving Trust, the UK's independent energy advice body, confirms it.

Here's why it's wrong: when your house is cold (14°C inside while you're out), the temperature gap between inside and outside is smaller, so it loses heat slowly. When kept warm (19°C), the gap is larger - the house loses heat faster, and the boiler has to continuously replace that lost heat.

The energy to reheat a cold house once is always less than the energy to maintain it warm all day.

How much does leaving it on cost?

Setting	Annual heating cost (typical semi-detached)
Constant 22°C	~£1,400
Low all day 17°C	~£1,100
Timer: on 1hr morning + 3hrs evening	~£720
Timer + smart thermostat	~£620

A timer-based approach saves £380 - 480/year compared to leaving it on constantly. That's not a small difference - it's the equivalent of nearly 3 months of heating for free.

The ideal timer settings

Morning: Turn on 30 minutes before you get up. Set to 19 - 20°C. Turn off when you leave (or 30 minutes before).

Evening: Turn on 30 minutes before you arrive home. Set to 19 - 20°C. Turn off 30 minutes before bed - residual heat keeps rooms comfortable.

Overnight: Off completely, or frost protection setting (7°C) if very cold weather is forecast.

If you work from home: Set to come on in your working hours and off in the evening. A smart thermostat that allows different zone temperatures lets you heat only the room you're working in.

What temperature should the thermostat be set to?

The World Health Organisation recommends 18°C minimum for healthy adults, 20°C for homes with elderly people or young children.

Each degree lower saves approximately 8 - 10% on heating bills. Setting from 21°C to 19°C saves around £160 - 200/year on a typical UK heating bill.

The single biggest heating mistake UK households make

Heating rooms they're not using.

If you have 5 rooms but only regularly use 2, heating all 5 to 20°C is wasteful. Thermostatic radiator valves (TRVs) - the knobs on individual radiators - let you set different temperatures per room.

Living areas: 19 - 20°C
Bedrooms (daytime): 14 - 16°C
Hallway and stairs: 15°C
Unused rooms: lowest setting (or off)

Cost of TRVs: £5 - 15 per radiator. Annual saving in a 4-bedroom house: £60 - 100.

Should I get a smart thermostat?

Smart thermostats (Hive, Tado, Google Nest, Drayton Wiser) cost £100 - 200 to install but offer:

Control from your phone - turn heating on 20 minutes before you arrive home
Geofencing - automatically turns off when you leave, on when you return
Room-by-room control (with multiple smart TRVs)
Clear reports showing exactly what your heating is costing

Typical saving: £80 - 150/year. Payback within 1 - 2 years.

What about electric heating?

If you heat with electricity (panel heaters, storage heaters, or a heat pump), smart timing matters even more - because electricity prices vary hugely throughout the day on smart tariffs.

Storage heaters are designed to charge overnight on Economy 7 cheap rates and release heat during the day. If yours isn't charging at night, check the timer setting.

Heat pumps work differently from gas boilers - running at a consistent lower temperature (40 - 45°C flow) continuously is more efficient than blasting at 60°C twice a day.

For any electric heating, running it during cheap overnight Octopus Agile windows rather than at peak evening rates can cut your heating bill dramatically.

When is electricity cheapest to run heating tonight?

AgileAlert shows live half-hourly prices for your UK region - see exactly when overnight rates are cheapest for your area.

Check Cheapest Times Tonight →

The three changes that save the most on heating

Change	Annual saving
Switch from "on all day" to a timer	£200 - 400/year
Turn thermostat down 2°C	£150 - 200/year
Turn off radiators in unused rooms	£60 - 100/year
Combined saving	£410 - 700/year

Frequently asked questions

Does it cost more to heat a cold house quickly?

In the very short term, your boiler works harder to raise temperature. But over a full day, maintaining a warm temperature in a cold house costs significantly more than reheating it once. The Energy Saving Trust confirms this clearly.

Should I turn heating off when I go to work?

Yes, unless your house has very poor insulation and takes several hours to reheat. Most UK homes reheat within 30 - 60 minutes. Use a timer set to come on 30 - 45 minutes before you return.

Is underfloor heating different?

Yes. Underfloor heating responds slowly, so a consistent low temperature is more efficient than cycling it on and off like radiators. Keep it at a steady 18 - 19°C rather than switching it fully off.

What's the cheapest temperature to keep the house at?

As low as you're comfortable with. Most UK households find 18 - 19°C in living areas and 16°C in bedrooms a good balance. Every degree lower saves 8 - 10% on your heating costs.

Is It Cheaper to Leave Your Heating On Low All Day or Turn It Off?