When should I turn the heating on for the winter?
There is no correct date, but there is a correct way to decide. What actually determines when heating becomes necessary, and why holding out has costs beyond comfort.
- Difficulty
- beginner
- Time
- 15 min
- Read
- 5 min
Short answer
Decide on indoor temperature rather than on a date in the calendar. The widely used guidance is around 18°C in occupied rooms, with warmer for babies, older people and anyone unwell, so a cheap thermometer in the coldest room tells you far more than the weather forecast does. Turning the heating on for a short test run in early autumn is worth doing regardless, because that is when faults reveal themselves while an engineer can still be booked.
Every year the same argument happens in every household, and it is unresolvable as posed because "when should the heating go on" is really three separate questions. One is about comfort, which is a matter of preference. One is about health, which is not — cold homes measurably increase respiratory and cardiovascular problems, and the risk is concentrated in specific groups. The third is about the building, because the point at which surfaces get cold enough to grow mould has nothing to do with how hardy the occupants are. The three have different answers and the strictest one should win.
Step by step
- Buy a thermometer and put it in the coldest occupied room.This converts an argument into a measurement. A cheap digital thermometer with a humidity reading costs very little and is the single most useful thing in this whole decision. Room temperature varies enormously between a south-facing lounge and a north-facing bedroom in the same house.
- Use the health guidance as the floor, not the target.Public health guidance in the UK centres on around 18°C for living areas, with higher temperatures recommended for babies, adults over 65, and people with long-term health conditions. That is not a comfort recommendation, it is a health one, and it is where the decision stops being a preference.
- Watch humidity as well as temperature.Mould does not need visible water, only a surface cold enough and air damp enough. A relative humidity persistently above about 65 per cent indoors, or condensation forming on windows in the morning, means the fabric is telling you before you feel cold. The catalogue's guides on dew point and indoor humidity cover the mechanism.
- Run the system briefly in early autumn as a test.Turn the heating on for half an hour on a mild day in September. You are checking that the boiler fires, every radiator gets hot, nothing leaks and there are no smells. Finding a fault then means a booked appointment; finding it in December means a queue in the cold.
- Set a schedule rather than reaching for the switch.A timed schedule that warms the house before you get up and before you get home uses less energy than heating on demand and produces a more comfortable house. The catalogue's guide on leaving the heating on low compares the approaches properly.
- Deal with the free things first.Closing curtains at dusk, draught-proofing, moving furniture off radiators and bleeding the system all raise the temperature you actually experience without raising the thermostat. Doing them before the heating goes on means the first setting you choose is a lower one.
- Adjust for who is in the house.A household with a young baby, an older relative or someone recovering from illness should not be running the same experiment in stoicism as a household of healthy adults. The guidance exists because the risk is real and unevenly distributed.
- Do not use the clocks or a specific date as the trigger.October is when most British households start, and that is a description of behaviour rather than a rule. A cold snap in late September in an exposed house needs heating; a mild October in a well-insulated flat may not.
Common mistakes
- Treating holding out as a virtue — A cold house is a health risk for some occupants and a mould risk for all of them, and mould remediation costs far more than the heating saved.
- Turning the thermostat up high to warm the house faster — A thermostat is a target, not a throttle. The house warms at the same rate either way, and the only effect is that it overshoots and wastes fuel.
If it doesn't work
House feels cold but the thermostat reads a reasonable number
Cause: Cold surfaces, draughts, or the thermostat in an unrepresentative spot — Fix: Radiant heat loss to cold walls and windows makes a room feel several degrees colder than the air temperature. The catalogue covers a house that feels cold with the heating on, and where a thermostat should be sited.
Radiators cold at the top when first switched on
Cause: Air in the system after standing all summer — Fix: Bleed them. It is the most common autumn heating complaint and the catalogue covers doing it properly, including repressurising afterwards on a combi.
Boiler will not fire on the first cold morning
Cause: A system that has sat unused since spring — Fix: This is exactly why the September test run matters. Check pressure and the thermostat first, then call — early autumn is a much shorter wait than the first frost.
Condensation on bedroom windows before you have turned the heating on
Cause: Warm damp air meeting cold glass, made worse by an unheated house — Fix: It is a ventilation and heating balance problem. Under-heating a house makes condensation worse, not better, which is one of the strongest arguments against holding out.
Worried about the cost of turning it on
Cause: A genuine constraint for many households — Fix: Heat the rooms you use rather than the whole house, use the free measures first, and check whether you qualify for support — the catalogue's guides on energy bill support and the Priority Services Register cover what exists.
Questions people ask
Is there an official date?
No, and there could not be — it depends on the building, the weather and who lives there. What exists is temperature guidance, and using that with a thermometer is a far better decision rule than any date.
Is it cheaper to leave the heating on constantly?
For almost all households, no. A house loses heat faster the warmer it is relative to outside, so keeping it warm all day costs more than warming it when you are there. The catalogue's guide on leaving the heating on low goes through the exceptions, which mostly involve heat pumps and very well insulated homes.
What temperature should bedrooms be?
Generally cooler than living areas — many people sleep better around 16 to 18°C. The important qualification is that a bedroom cold enough to grow mould in the corners is too cold regardless of how well anyone sleeps.