Ask 10 people what temperature their home should be, and you'll get 10 answers, most of them delivered with total confidence. Somebody will mention 21C. Somebody else will insist their grandmother managed fine at 15C.
There's plenty of good guidance to be found on this subject, and it's more nuanced than being told a single number. Different rooms suit different temperatures, and the difference between the warmest and coolest rooms in your house is where a fair amount of money sits.
Here's the only guide you need, pulling together what all trusted evidence says, room by room.
What temperature should your home be?
The starting point for most UK advice is 18C. The World Health Organization's Housing and Health Guidelines make this a strong recommendation, proposing 18C as a safe, well-balanced indoor temperature to protect the health of general populations in countries with temperate or colder climates during cold seasons.
UK guidance follows the same line, expanding on WHO’s guidance subtly. Public Health England's review of minimum temperature thresholds concluded that heating homes to at least 18C in winter poses minimal risk to the health of a sedentary person wearing suitable clothing, and that the threshold matters most for people over 65 or with pre-existing medical conditions, for whom temperatures slightly above it may be beneficial. For healthy people aged one to 64 who are active and dressed appropriately, it is noted that they may wish to heat their homes to slightly below 18C.
Comfort sits a little higher. The Energy Saving Trust suggests setting your thermostat to the lowest comfortable temperature for your needs, which for most people falls between 18C and 21C.
So 18C is the floor and 21C is roughly the ceiling for most households. What happens between those two numbers depends on which room you’re in.
What's the ideal temperature for each room?
Your thermostat measures one spot in one room, usually a hallway. Thermostatic radiator valves let you vary everything else.
For your living room, it’s recommended that the temperature is between 20C and 21C. This is the warmest room in the house for a simple reason. Sitting still generates almost no body heat, and an evening on the sofa is the point at which you'll feel a cool room most.
The same applies to a home office if you're at a desk all day, and to any room used regularly by someone older or less mobile, where the guidance points slightly above the 18C threshold rather than at it.
Your kitchen should be 18C or below. Cooking generates a fair amount of heat, and so do kitchen appliances, the extractor pulling warm air out, and the simple fact that you're on your feet. Kitchens usually need less from the heating system than any other occupied room in the house.
And your bathroom should be between 20C to 22C, but only when you're using it. Stepping out of a shower with wet skin is the one situation where a warmer room genuinely earns the energy, and bathrooms are small enough to heat quickly. A timed boost around morning and evening use beats holding the room warm all day.
Hallways, landings and stairs ideally 16C to 18C. You pass through these spaces rather than occupy them, and they connect to every other room, so heat spreads out of them constantly. If your thermostat lives in the hall, this is worth knowing. The hall is the room the thermostat is heating, and every other room is being heated relative to it.
As for your bedroom, the ideal temperature is between 16C and 18C. Most people find they sleep better in a cooler room, and the body's core temperature drops naturally overnight, so a bedroom held at living room temperature works against the process.
Bedding does the rest of the work. The caveat is that overnight guidance for vulnerable people still points to 18C, so treat the lower end of that range as a choice for healthy adults rather than a rule for the whole house.
The Lullaby Trust recommends keeping a baby's room between 16C and 20C, which helps lower the risk of SIDS by preventing overheating. The charity also notes that it's rarely necessary to run heating all night, and that where parents do, it should be set low and certainly no higher than 20C.
This range feels cool to most adults, which is exactly why a room thermometer is essential for baby and infant rooms rather than trusting your own sense of warmth.
And finally, spare rooms and rooms you rarely use should be around 15C to 16C. Here's where people get it wrong, though. Turning the radiator off entirely saves money in the short term. It also creates a cold room that pulls heat out of the rooms next to it, with condensation collecting on the cold surfaces. A low background setting costs relatively little and protects the room.
Can a room be too cool?
Yes, and the issue is moisture rather than comfort. Warm air holds more water vapour than cold air. When that air meets a cold surface, such as a window, an external wall or the corner of an unheated room, the moisture condenses out. Do that repeatedly through a winter and you get mould.
Relative humidity is the number to watch alongside temperature. Most UK guidance recommends a range between 40 and 60 per cent. Readings that sit persistently above 60 per cent signal a ventilation or heating problem worth acting on. A basic hygrometer will give you this information if you suspect any issues. The practical version: heat rooms a little, ventilate them properly, and keep every room in at least occasional use.
How much can you save by turning the thermostat down?
By turning your thermostat down from 22C to 21C, the Energy Saving Trust says you can save £120 a year in Great Britain and £80 in Northern Ireland. That's a meaningful sum for a change most people stop noticing within a week.
Two caveats: the saving scales with how far above the comfort range you started, so a household already at 19C has far less to gain than one at 23C. And the 18C floor exists for good reason, particularly in homes with older residents, young children or anyone with a heart or lung condition. Dropping below it to save money is a false economy that the evidence links to raised blood pressure and worse respiratory outcomes.
The better saving usually comes from heating fewer rooms to the top of the range rather than heating the whole house cooler.
Does the right temperature change if you have a heat pump?
The target temperatures stay the same. How you reach them changes completely.
Heat pumps hold a steady temperature over long periods rather than heating hard in short bursts, so the room-by-room approach above works well with them, provided you set it up as a background level with variation rather than as a series of on-off cycles. Deep setbacks in individual rooms force the system to work harder to recover them.
Anyone in their first heat pump winter will find the adjustment period takes a week or two.
How do you find the right temperature for your home?
Start at 18C on the thermostat and give it a few days before deciding. Many households that consider 22C essential have never properly tested the alternative, and a week is long enough for your body to adjust to a change of a degree or two.
Then work outwards with the radiator valves. Turn the living room up, turn the bedrooms and spare rooms down, and leave the hallway alone. A cheap room thermometer in two or three rooms will tell you what's actually happening, which is often some distance from what the thermostat claims.
Smart meters and supplier apps, including Octopus Energy's, show daily consumption, so you can see the effect of a change within about a week rather than waiting for a quarterly bill.
The right temperature for your home is the lowest one that keeps everyone in it comfortable and well. Finding it takes a fortnight of small adjustments, and it's the cheapest heating upgrade available.
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