Socks come off, jumpers get tossed on the sofa, and someone inevitably cracks a window because it suddenly feels stuffy. The smart meter on the counter flicks from calm green to angry orange. You can almost hear the money drifting out through the glass, along with a little steam from dinner and the day’s damp washing on the radiator. It feels cosy, sure. It also feels slightly wrong. Not guilty, exactly — more like a nagging itch that you can’t place. The air is warm but not fresh. The bill will come. The mould might follow. The house is trying to tell you something. Listen closely. A simple rule changes everything.
The quiet price of “too warm”
We talk about heating like it’s binary: cold or warm, on or off. What actually drains your wallet is the gap between inside and out. Push the thermostat to 22–23°C on a crisp night and your home leaks heat faster, your boiler works harder, and every draft becomes more expensive. Overheat the air and you dry out your skin and throat, while cold corners still hit dew point and collect condensation. Homes don’t just get warm; they get uneven. That’s where mould takes root, where paint bubbles, where bills swell quietly in the background.
In one Leeds semi I visited, the family kept their lounge at 22.5°C all winter because “that’s what everyone does.” The bill was roughly £320 higher than the previous year, despite similar weather. They also battled condensation on the bay window every morning and a persistent cough that eased when they dropped to 19°C and ran the extractor longer after showers. **Drop your thermostat by just 1°C and you’ll likely cut your heating use by around 8–10%.** That’s the rough, widely cited rule. Multiply it across a season and it’s not small change.
There’s simple physics under this. Heat moves from warm to cold; the bigger the difference, the faster it escapes through walls, windows and little gaps around doors. Overheating raises that difference, so losses accelerate. Your boiler then cycles more often, which is especially wasteful if the flow temperature is high and the system can’t condense efficiently. Rooms with cold surfaces meet humid indoor air at the dew point, so moisture sticks as droplets on glass, at skirting level, behind wardrobes. That’s when comfort slips even as energy use climbs. Hot isn’t the same as healthy.
The 19°C rule (and how to use it)
Here’s the simple move: pick 19°C as your day-time baseline, then layer comfort on top. Set the main thermostat to 19°C for living spaces, use 16–18°C for bedrooms, and give bathrooms a short boost to 21°C when needed. Try a one-degree step-down each week until it feels right. Close internal doors to zone the heat, and set your boiler flow temperature to around 55–60°C so it condenses properly. **Comfort lives in layers and airflow, not at 23°C.** Think warm socks, a throw on the sofa, and a ten-minute cross-vent after cooking or showering to purge moisture without dumping all your heat.
Common traps are sneaky. Cranking the dial to 25°C doesn’t heat faster; it just overheats later. Parking a sofa in front of a radiator strangles it. Drying clothes on rads loads the air with moisture and leaves cold glass running with water in the morning. Turning the heating fully off for long stretches can let the house get clammy, then you pay more later trying to chase comfort. Let’s be honest: nobody really does that every day. Bleed radiators if they gurgle, don’t bury thermostatic valves behind curtains, and place the main thermostat where life actually happens — not behind a bookcase.
“Think of 19°C as your anchor, then tune the house gently: a degree up for Grandma’s visit, a degree down on a sunny afternoon. The cheapest heat is the heat you don’t need to make.”
- Lower combi boiler flow temp to 55–60°C for better efficiency.
- Fit draught strips to letterboxes and gaps; heavy curtains after dusk.
- Use reflector foil behind radiators on external walls.
- Run extract fans during and 10 minutes after cooking or showers.
- Aim for 40–60% indoor humidity; a small dehumidifier can help.
What you save when you stop overheating
Money, yes — often hundreds across a season — but also quiet things you’ll notice later. Fewer steamy windows at breakfast. Less sniffly dryness at night. Furniture that doesn’t warp near a blasting radiator. A boiler that sounds calmer because it’s not sprinting. *Cold is a feeling, not just a number.* When your baseline sits at 19°C and the air is drier, you can nudge comfort with small moves: a warm drink, slippers, closing a door. We’ve all had that moment where a house feels oddly more welcoming at 19°C with fresh air than at 22°C with stale air. **The cheapest heat is the heat you don’t need to make.** And the cosiest rooms aren’t the hottest — they’re the most balanced, the most honest about how a home really breathes.
| Key points | Detail | Reader Interest |
|---|---|---|
| 19°C rule | Set 19°C for living areas, 16–18°C for bedrooms; boost bathrooms briefly | Actionable, saves ~8–10% per degree |
| Moisture management | Vent after steam events; target 40–60% humidity | Less condensation, better health |
| System tuning | Flow temp 55–60°C, bleed rads, clear TRVs | Quieter, cheaper heating |
FAQ :
- What’s the ideal thermostat setting in winter?For most healthy adults, 19°C in living spaces works well. Bedrooms often feel best at 16–18°C with a good duvet.
- Is 19°C too cold for children or older people?Some need warmer. Nudge to 20–21°C in rooms they use, and prioritise layers, warm bedding and steady humidity.
- Should I keep heating on low all day?In many UK homes, timed schedules with a steady 19°C beat bills. Long off-periods can cause damp and reheat spikes.
- Does turning off radiators in spare rooms save money?Turn them down, not off. Keep those rooms at 15–16°C to prevent damp and avoid dragging heat from warmer rooms.
- Will a dehumidifier make the house feel warmer?Lower humidity reduces that clammy chill. A small unit in laundry-prone rooms can cut condensation and improve comfort.
