That lingering cold at home isn’t imagined, and it’s not always solved by simply turning up the heat. The uneasy chill often comes from a quiet combination of basic physics, human biology, and everyday habits that subtly work against comfort. Even when the thermostat shows a sensible number, your body may be reacting to far more than warm air alone.
Why the same 20°C feels different to everyone
On paper, 20°C sounds reasonable. Many energy authorities even recommend it as a standard indoor setting. Yet in one room, someone may sit comfortably in a T-shirt while another reaches for a blanket. That’s because thermal comfort depends less on a single number and more on how your body gains and loses heat within its surroundings.
Your brain doesn’t read the thermostat. Instead, it listens to signals from your skin temperature and core warmth. What you feel on the surface and deep inside shapes your perception. This is why saying “I’m cold” can mean something entirely different for two people sharing the same space.
How walls, windows and surfaces affect warmth
Air temperature is only part of the story. Your body constantly exchanges heat with walls, floors, ceilings, furniture and windows. When those surfaces are cold, your body loses heat toward them, much like standing near a cold slab of stone. The air may be at 20°C, yet your body experiences something closer to 17 or 18°C.
What you actually feel is a blend of air temperature and the mean radiant temperature of nearby surfaces. Homes that feel colder than the thermostat suggests often share common features:
- Poorly insulated walls that remain chilly
- Older or single-glazed windows radiating cold inward
- Uninsulated tile or concrete floors
- Large, open rooms where heat mixes unevenly
This explains why a well-insulated home set slightly lower can feel warmer than a poorly insulated space heated higher.
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Draughts: the unseen drain on warmth
Even gentle air movement can transform how a room feels. Small leaks around window frames or door gaps quietly pull heat from your skin through convection. You may notice this when sitting near a window or when your hands and ankles stay cold at a desk by the door.
Simple tests reveal a lot. Hold a thin tissue or candle near frames and vents and watch for movement. Sealing gaps, adding draught excluders, or slightly rearranging furniture can reduce that constant sense of a cold corner.
Humidity and how it changes temperature perception
Indoor humidity strongly influences comfort, even if you never check it. Most specialists suggest keeping relative humidity between 40% and 60% for balanced warmth.
When indoor air is too dry
Heating systems often dry the air in winter. Below roughly 35–40% humidity, moisture evaporates faster from your skin. Dry hands, cracked lips and irritated airways become common. This evaporation subtly cools your skin, making the room feel colder than it is.
When humidity is too high
In older or poorly ventilated homes, moisture can build up. High humidity in cooler rooms makes walls feel damp and cold and encourages mould. The result is a clammy chill that many find more uncomfortable than dry cold, even at 20°C.
- Below 30%: dry skin, scratchy throat, sharp air, harder to warm up
- 40–60%: balanced air, comfortable for most with suitable clothing
- Above 65%: heavy air, damp chill, colder surfaces, condensation risk
Why some people always feel colder
Two people, one room, one thermostat — very different reactions. Biology plays a major role.
Age, hormones and body makeup
Several factors influence how 20°C feels:
- Age: older adults often lose heat faster due to circulation changes
- Hormonal shifts: menstrual cycles, pregnancy or thyroid changes affect heat regulation
- Muscle mass: muscles generate heat, acting like internal radiators
- Fat distribution: insulation varies, with hands and feet often staying cold
This is why a teenager in shorts and a grandparent under a blanket can sit together at the same temperature.
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Lifestyle, metabolism and daily movement
Habits train your body. Someone active outdoors builds tolerance to cooler air, while long hours seated reduce heat production. Less movement means muscles burn less energy, making 20°C feel much cooler.
Short walks, gentle stretches or brief bursts of activity can noticeably raise internal warmth, even without changing the thermostat.
When feeling cold may point to health issues
Occasional winter chills are normal. Feeling constantly cold indoors, while others are comfortable and heating is adequate, may signal an underlying issue. Doctors often check for:
- Underactive thyroid
- Iron deficiency or anaemia
- Circulatory conditions such as Raynaud’s phenomenon
- Very low calorie intake or rapid weight loss
- Medication side effects
If 20–21°C feels unbearable and cold hands and feet persist year-round alongside fatigue, a medical check may be more useful than adjusting the boiler.
Simple ways to make 20°C feel warmer
Raising the thermostat isn’t always necessary. Small changes often shift comfort significantly:
- Cover cold floors with thick rugs where you sit or stand
- Soften cold surfaces using curtains, throws or wall coverings
- Layer clothing to trap insulating air
- Move seating away from windows and external walls
- Check humidity with a simple hygrometer
Warm feet, protected kidneys and a bit more movement often matter more than another notch on the thermostat.
Key concepts behind personal comfort
Two ideas help explain what’s happening at home:
- Thermal sensation: your subjective feeling of hot, neutral or cold
- Operative temperature: a blend of air temperature and radiant surface temperature
If the thermostat reads 20°C but walls and windows sit at 14–15°C, your operative temperature may feel closer to 17–18°C. Your body reacts to that reality, not the tidy display.
Thinking in terms of operative temperature makes priorities clearer: seal draughts first, move furniture off cold walls, add rugs, and adjust the thermostat last.
What a winter evening at 20°C can feel like
Picture two identical flats, both set to 20°C. In one, insulation is good, humidity sits around 45%, rugs cover the floor and seating stays away from windows. The resident wears socks, moves occasionally and feels comfortable, even considering turning the heat down.
In the other, walls are bare and cold, humidity is high from indoor laundry, windows leak slightly and the person sits barefoot on tile for hours. Same thermostat, yet they reach for a blanket and still feel cold.
Both scenes are common. Understanding the difference helps you act on the right factors — building, air and body — instead of blaming the thermostat when 20°C leaves you shivering.
