Ideal room temperature UK: by room, by person, and the cost

What is the ideal room temperature?

The ideal room temperature for most UK homes is about 21°C in a living room and 18°C in a bedroom. Those are the figures in the government’s housing guidance, updated in June 2026.

Turn the dial to your room's temperature

No UK body sets one figure for every room and every person. We found no UK figure for a home in summer, so the table gives the nearest marker and who says so:

Room or person	Winter	Summer
Living room	21°C, says government housing guidance. The UK Health Security Agency (UKHSA) says at least 18°C.	No UK figure. The World Health Organization (WHO) gives a London example: low risk at 22 to 23°C, and about 25°C at most.
Bedroom	18°C, says government housing guidance. Around 16 to 18°C usually suits sleep, says The Sleep Charity.	No UK figure. The Sleep Charity says over 24°C is more likely to cause restlessness.
A baby’s room	16 to 20°C, say the NHS and The Lullaby Trust.	The same range. Use lighter bedding and clothing on hot nights.
An older person, or someone with a health condition	At least 18°C, says Public Health England’s 2014 review. Slightly warmer may be better.	Below 26°C, going by UKHSA’s care guidance for high-risk groups.
A home office	No UK figure for homes. The Health and Safety Executive’s code suggests at least 16°C for indoor work. The Energy Saving Trust says 18 to 21°C suits most people at home.	No UK figure. There’s no legal maximum for workplaces either.

Our pick for a London home is 21°C. We use it as the all-round target on this site, for three reasons:

Government housing guidance calls around 21°C a healthy indoor temperature.
A WHO working group found no clear risk for healthy people at rest between 18 and 24°C.
21°C sits below 22 to 23°C, WHO’s low-risk example for heat in London.

Treat 21°C as a target for the room, not as the cheapest setting. Air con set lower than 26°C in summer costs more. What temperature to set on air con.

No single figure suits everyone, because clothes, activity, draughts and humidity all change how a room feels. A room thermometer gives you the real figure. A thermostat or remote reads the air at its own sensor, which may not match the spot where you sit.

Many homes sit below 21°C in winter. A government survey measured English living rooms at an average of 18.5°C in houses and 19.5°C in flats. Normal room temperatures in the UK.

Sources: government housing guidance (June 2026, section 9), UKHSA’s winter advice (April 2026) and WHO’s Housing and Health Guidelines (2018), chapters 4 and 5. Also The Sleep Charity, the NHS, The Lullaby Trust, Public Health England and GOV.UK care guidance. Work and home: the Health and Safety Executive, the Energy Saving Trust (October 2026) and the Energy Follow Up Survey (2017 to 2019).

Why do people need a particular temperature?

People need a particular room temperature because the body has to hold its core at around 37°C. The room decides how hard that job is.

The body has two main ways to do it:

In a warm room: you sweat, and the sweat cools you as it evaporates. Humid air slows this down.
In a cold room: blood vessels narrow, which holds heat in and raises blood pressure.

Both take effort, and the strain falls on the heart and lungs. Some bodies have a harder job:

Older people: temperature control weakens with age, and they may not feel heat or cold as well.
Babies and young children: their temperature control isn’t fully developed.
People with heart or lung conditions: WHO says their bodies respond less well to heat.

The body also needs to cool down to sleep. Body heat peaks in the late afternoon, then drops in the evening to prepare you for sleep. The Sleep Charity says a fall of about half a degree in core temperature helps switch sleep on.

Cooling down before bed makes it easier to drop off, so a hot room works against you.

Sources: the NHS, WHO’s Housing and Health Guidelines and government housing guidance, sections 9 and 14. Also Public Health England, the Energy Follow Up Survey and The Sleep Charity.

What happens when a room is too hot?

A room that’s too hot disturbs sleep first, then puts more strain on the heart and lungs the longer the heat lasts. Government housing guidance says harm from heat comes sooner than harm from cold.

Sleep: The Sleep Charity says over 24°C is more likely to cause restlessness. In a hot week in June 2018, 71% of those asked in a government survey struggled to sleep on at least one night.
Heart and lungs: long spells of heat add stress to both. UK guidance says hot weather can raise the risk of heart attack and stroke.
Dehydration: sweating loses water, so drink regularly. Older people and the very young are most affected.
Concentration: the Health and Safety Executive lists an inability to concentrate as a symptom of heat stress.
Heat exhaustion: the NHS lists tiredness, dizziness, headache and a high temperature among the signs.

A single broken night is unlikely to harm your health, though long spells might. The same survey counted three or more hot nights in a row as unacceptable.

UKHSA says these people are most at risk in hot weather:

people aged 65 and over
babies and young children aged 5 and under
pregnant women
people with heart problems, breathing problems or dementia
people on certain medications
people who live alone

Older people can be at risk without feeling it. In the same survey, homes with a pensioner overheated more often, yet fewer of them reported it. A thermometer helps, so check on anyone at risk.

UKHSA estimates 1,504 heat-associated deaths in England in summer 2025, including 317 in London. Its interim estimate for May and June 2026 is 2,877. What heat means for London homes.

Call 999 if someone is still unwell after 30 minutes in a cool place. Also call if they’re confused, or their skin is hot and not sweating. Heatstroke is a medical emergency.

Sources: The Sleep Charity, the Energy Follow Up Survey and government housing guidance, section 14. Also GOV.UK care guidance, UKHSA’s hot weather advice (July 2026), the Health and Safety Executive and the NHS. Deaths: UKHSA’s reports for 2025 and May and June 2026. The 2026 figure leaves out the July heat.

What happens when a room is too cold?

A room that’s too cold raises blood pressure, lowers your resistance to infection, and makes damp and mould more likely. Government housing guidance sets out how the risk grows:

Room temperature	What the guidance says
Below 19°C	A small risk begins for older people and others at risk.
Below 18°C	Blood pressure rises, which raises the risk of heart attacks and strokes.
Below 16°C	Serious health risks, with a much greater risk of breathing and heart problems.
Below 12°C	The heart and circulation take on more strain.
Below 10°C, if it lasts	Hypothermia becomes a real risk.

The effects show up in several ways:

Circulation: narrowed blood vessels put stress on the heart and circulation.
Breathing: WHO says cold air inflames the lungs. That raises the risk of asthma attacks, worse lung disease and infection.
Sleep: The Sleep Charity says a room of about 12°C makes it hard to drop off. Housing guidance says sleeping in a cold bedroom substantially raises the risk to health.
Damp and mould: under-heated homes collect more moisture on walls and windows. In a government survey, main bedrooms were colder in homes with damp.
Mood: cold homes can bring stress, anxiety and depression, and some people stop having guests round.

UKHSA says these people are among those most at risk from cold:

people aged 65 and over
people with long-term health conditions
pregnant women
young children
people at risk of falls
people who live alone or rarely go out

UKHSA estimates 2,200 deaths were associated with cold weather in England in winter 2025 to 2026. Why cold still matters in London.

Sources: government housing guidance, section 9, WHO’s Housing and Health Guidelines, chapter 4, and The Sleep Charity. Also GOV.UK damp and mould guidance (April 2026), the Energy Follow Up Survey, UKHSA’s winter advice and its cold mortality report (October 2026).

What temperature suits babies and children?

A baby’s room should be 16 to 20°C, say the NHS and The Lullaby Trust. For children, The Sleep Charity says around 18°C is ideal.

This is general information, not medical advice. If you’re worried about a baby or child, speak to your health visitor or GP, or contact NHS 111.

How babies and young children cope with heat and cold

Babies and young children cope less well with heat and cold, because their bodies are still developing. Government housing guidance says a very young child’s temperature control isn’t fully developed.

Heat: UKHSA puts children aged 5 and under in its higher-risk group. It says dark urine or dry nappies may mean a child needs more fluids.
Cold: infants don’t move about much, and they spend more time indoors in cold weather.

Sources: government housing guidance, sections 9 and 14, WHO’s Housing and Health Guidelines, and UKHSA’s guidance for schools and early years (July 2026).

Why overheating matters for babies

Overheating matters for babies because the NHS says it can increase the risk of sudden infant death syndrome (SIDS). SIDS is rare, the NHS says, and there are simple things you can do to lower the risk:

Use a room thermometer where your baby sleeps, because temperature is hard to guess.
Feel your baby’s chest or the back of their neck. Cool hands and feet are normal.
If their skin is hot or sweaty, remove a layer of bedding or clothing.
Use light bedding or a lightweight baby sleeping bag, not a duvet or quilt.
Skip hats indoors, and keep the cot away from heaters and direct sun.

Many bedrooms pass 20°C in a hot spell. English main bedrooms averaged 24.8°C in July 2018. On hot nights, The Lullaby Trust suggests:

lighter bedding and clothing
an open door and window, if it’s safe
a fan to cool the room, not aimed at your baby

In cold weather, it says the heating rarely needs to stay on all night. If it does, keep it no higher than 20°C.

Sources: NHS advice on SIDS, NHS advice on hot weather, The Lullaby Trust (April 2026) and the Energy Follow Up Survey.

Does sleep help a child grow?

Sleep is when much of a child’s growth hormone is released, though how far sleep changes growth isn’t proven. Here’s what we found:

What’s known: growth hormone comes in spurts day and night, especially during sleep, says Alder Hey Children’s Hospital. A 2024 review says it rises in deep sleep.
What’s less clear: the same review calls the evidence limited, and often old or poor quality. Studies disagree on how closely the hormone follows sleep stages.
What isn’t proven: the review lists growth problems among the effects of poor sleep. The survey it names, of 5,145 children, found a weak link between sleep and height. That doesn’t show that less sleep causes less growth.

We found no reliable source that says a hot room stunts a child’s growth, so we don’t claim it. Two large studies in Africa on hot climates and child growth disagree, and food and infection may explain their results. Neither measured a room.

Sources: Alder Hey Children’s NHS Foundation Trust and a review in Frontiers in Endocrinology (January 2024). Climate studies: Cornell University (July 2022) and The Lancet Planetary Health (March 2020).

Does a hot bedroom cut children's sleep?

A hot bedroom may cost children a little sleep, but the studies are few, and we found none from the UK. These are the results we found:

The Netherlands: among 3,340 young people averaging 13.5 years old, each 5°C rise in night air temperature went with about 4 minutes less sleep.
Spain: the same study found no link among 587 young people, most of them measured in autumn.
The United States: among 46 children aged about 11, sleep was worse in rooms either side of the group’s average of 22 to 23°C. The effect looked stronger in colder rooms.

These studies show a link, not a cause. The European study estimated the air outside each home, not the bedroom itself.

Sources: Environment International (June 2025), ISGlobal (July 2025) and the Journal of Applied Developmental Psychology (March 2023).

Does heat affect learning?

Heat can affect learning, says the Department for Education, because high temperatures can be a key factor in children’s concentration at school. Research it published in June 2025 gives these estimates for England:

warm weather already costs the equivalent of 6.7 learning days a year, on average
that could reach 8.2 days by 2050, with 2°C of global warming
learning could become very difficult when classrooms reach 35°C

The department calls these figures indicative.

Source: Department for Education (June 2025).

What does each degree cost?

Each degree costs most on central heating, at about £120 a year on one estimate. A degree of air con in one room costs about £2 to £12 a year, on the best figures we found.

What changes	Whose figure	Energy saved a year	Estimated saving a year
Central heating, 22°C down to 21°C	Energy Saving Trust, Great Britain	Not given	£120
Air con heating, 2.5 kW unit, 1°C lower	Japan’s energy agency, Tokyo house	15.8 kWh	£4.16
Air con heating, 4 kW unit, 1°C lower	The same	45.2 kWh	£11.90
Air con cooling, 2.5 kW unit, 1°C higher	The same	8.8 kWh	£2.32
Air con cooling, 4 kW unit, 1°C higher	The same	20.1 kWh	£5.29

Read these figures with care:

No UK test: we found no UK test of what a degree of air con costs. Japan’s figures are for a wooden house in Tokyo, with 112 days of cooling and 169 of heating.
Prices: the pounds beside Japan’s figures are our estimate, at Ofgem’s capped price of 26.32p per kWh.
The £120: the Energy Saving Trust doesn’t say which home that’s for. Its figures assume gas at 6.5p per kWh, and today’s capped price is 7.97p.

Three habits keep the cost down:

Heating: set the thermostat to the lowest comfortable temperature. The Energy Saving Trust says that’s 18 to 21°C for most people.
Cooling: set it as high as you’re comfortable. Daikin and Panasonic suggest 26 to 28°C to save energy. That’s an energy range, not a health target.
Hours: run it for less time. On a 2.5 kW unit cooling, Japan’s figures show an hour a day less saves nearly three times what one degree saves.

Don’t chase a saving past the health markers. UK advice is to heat rooms you use a lot to at least 18°C. Someone at risk needs a room below 26°C in summer.

A 2.5 kW wall unit costs about 16p an hour at full power, and about half that once it eases off. These are estimates at today’s capped price. Work out your own running cost.

Sources: the Energy Saving Trust (October 2026) and its data page, and Japan’s Agency for Natural Resources and Energy. Also Ofgem’s price cap, 1 October to 31 December 2026, Daikin’s FTXM user guide, Panasonic’s BZ and UZ instructions, and UKHSA’s winter advice.

What are the pros and cons of each setting?

The pros and cons of each setting depend on who’s in the room and what it’s for. Read across from your room’s temperature. The table assumes people at rest in everyday clothes, so treat the edges as a guide.

Room temperature	Good for	What it costs you
Below 16°C: too cold	Lower heating bills, and little else.	Serious health risks begin below 16°C, so warm the room. A room of about 12°C is too cold for most people to drop off. Condensation and mould are more likely.
16 to 17°C: cool	Good for sleep under warm bedding, but cold if you’re sitting still. Suits a baby’s room, and active people in warm clothes.	Below 18°C, blood pressure rises. Older or unwell people need a warmer room.
18 to 20°C: mild	Healthy for most people, and a good range for bedrooms. Suits a baby’s room too. 20°C is the usual thermostat setting in England.	Older or unwell people may need a little more, as below 19°C brings a small risk for them. Each degree of heating adds to your bill.
21 to 24°C: comfortable	Comfortable and healthy for living, but warmer than most adults need for sleep. Suits living rooms and home offices.	Too warm for a baby’s room. Heating to the top of this band costs more, at about £120 a year for 22°C against 21°C, on the Energy Saving Trust’s estimate. Cooling this far costs more than stopping at 26°C.
25 to 26°C: warm	Daytime for most healthy adults. Lower air con bills, as 26°C is the cool end of makers’ energy range.	Warm enough to make sleep restless, and close to the limit for high-risk people. UKHSA’s line for them is 26°C, and WHO’s London example tops out at about 25°C.
27 to 28°C: too warm	The lowest air con bills. Makers suggest 26 to 28°C to save energy.	Too warm for sleep, and hard on older people and young children. High-risk groups can struggle to cool themselves above 26°C.
Above 28°C: hot	Nothing at home. Treat it as a warning.	Hot enough to strain the body, so cool the room or move. Sweating, dehydration and stress on the heart and lungs all grow. Drink regularly, stay somewhere cooler, and check on people at risk.

Sources: government housing guidance, sections 9 and 14, The Sleep Charity, the NHS and The Lullaby Trust. Also Public Health England, WHO’s Housing and Health Guidelines, the Energy Follow Up Survey and the Energy Saving Trust. Heat and settings: GOV.UK care guidance, UKHSA’s hot weather advice, Daikin and Panasonic.

How do you get a room to the right temperature?

The cheapest way to get a room to the right temperature is to start with what you already have. Fit something new last.

If a room is too hot

A room that’s too hot usually needs shade and air before it needs a machine. Work down this list, and stop when the room is comfortable:

Check the real temperature with a room thermometer.
Close blinds and curtains on sunny windows.
Keep windows shut while it’s hotter outside than in, then open them when it’s cooler, if it’s safe.
Check the heating is off, and turn off lights and equipment you aren’t using.
Use a fan if the air is below 35°C, and don’t point it straight at your body.
Move to a cooler room to sleep.
Cool one room with air con, and keep its doors shut.

What each step costs to run and when to open the windows.

Sources: UKHSA’s checklist and hot weather advice (July 2026), and the Energy Saving Trust (October 2026).

If a room is too cold

A room that’s too cold usually needs draughts stopped and the heating set well. Work down this list:

Check the real temperature with a room thermometer.
Stop draughts, the top reason people gave for a cold living room in a government survey. Keep vents open, because a home still needs fresh air.
Use the heating timer and thermostat, and set the lowest temperature you’re comfortable with.
Heat the rooms you use most to at least 18°C.
Sort out any damp, because it makes a home harder to heat.
Add insulation to the roof, walls and floor where you can.
Look at the heating itself. Air-to-air heat pumps explained.

Sources: the Energy Follow Up Survey, government housing guidance, section 9, the Energy Saving Trust and UKHSA’s winter advice.

When you don't need air con

You may not need air con if these steps keep a bedroom near 24°C at night and other rooms below 26°C by day. Those are the markers on this page, not a rule.

Government housing guidance says to try these steps first, because they use less energy. It says air con suits homes where windows can’t stay open, because of noise, pollution, security or the risk of falls.

Where those steps aren’t enough, a fitted unit can cool the room that matters most. Cooling a bedroom, work out a starting size, or see when air con isn’t the answer. Options if you rent.

Source: government housing guidance, section 14.

Room temperature questions

What's the best temperature for sleep?

The best temperature for sleep is around 16 to 18°C for most adults, says The Sleep Charity. That’s the ideal bedroom temperature at night. Young children and older people may need a slightly warmer room.

Public Health England says keeping 18°C overnight may help people over 65 or with a health condition. Settings for a good night’s sleep.

What's too hot to sleep?

Too hot to sleep starts at about 24°C for most people. The Sleep Charity says anything over that is more likely to cause restlessness.

New homes checked by computer model face a separate test. Bedrooms shouldn’t pass 26°C for more than about 32 night hours a year. That’s a design test, not a health limit.

Sources: The Sleep Charity, the Energy Follow Up Survey, quoting CIBSE TM59, and Approved Document O, section 2.

What's a normal room temperature in the UK?

A normal room temperature in the UK is about 18 to 20°C in winter, going by average readings from homes in England. The usual thermostat setting is 20°C.

February 2018, the coldest month measured: living rooms averaged 18.5°C and main bedrooms 18.1°C.
July 2018, the hottest month measured: living rooms averaged 24.4°C and main bedrooms 24.8°C.
London, summer 2018: living rooms averaged 24.2°C and bedrooms 24.1°C, the highest of any region.

Summer 2018 was the hottest on record at the time, so a typical summer may differ. We found no newer measured survey.

Source: the Energy Follow Up Survey’s thermal comfort and heating patterns reports.

What temperature should a baby's room be?

A baby’s room should be 16 to 20°C, say the NHS and The Lullaby Trust. Use a room thermometer, and check your baby’s chest or the back of their neck. More on babies and children.

What temperature should a house be?

A house should be about 18 to 21°C in the rooms you use. The Energy Saving Trust gives that range for most people, and UKHSA says to heat rooms you use a lot to at least 18°C.

What's a healthy room temperature?

A healthy room temperature is around 21°C, says government housing guidance. A WHO working group found no clear risk between 18 and 24°C for healthy people at rest.

Is 21°C the right setting for air con?

21°C is a comfortable target for a room, but it isn’t the cheapest air con setting. On cooling, Daikin suggests 26 to 28°C to save energy, so start at 26°C and come down a degree at a time. What temperature to set.

Ideal room temperature: what's right and why