Cut your heating bill by 20% without renovation: could grandma’s 19°c routine save you £300?

A quiet, old-school habit is winning new converts.

Across the country, households are testing a simple routine: keep a steady low heat and move fresh air through the home on a strict schedule. The aim is drier rooms, fewer cold spots and less boiler cycling. Many users report calmer comfort and smaller gas bills.

The forgotten routine: steady heat and smart air

In the 1950s, before cavity wall insulation or modern ventilation, families relied on stable background warmth and brief blasts of outside air. The idea sounds quaint, yet it answers a very modern problem: moisture. Steam from showers, cooking and everyday breathing lingers on cold surfaces. That moisture feeds mould, chills the body and forces the boiler to work harder to reheat damp rooms.

The method restores balance. Keep walls, ceilings and furnishings gently warm so they stop acting like giant dehumidifiers. Then, twice a day, sweep stale, humid air out and bring crisp, dry air in. Lower humidity means fewer chills, less condensation and faster, cheaper heating.

Set radiators to a constant 19–20°c. Ventilate twice a day for ten minutes with windows on opposite sides open. Keep draughts out at floor level.

What you need in a typical UK home

• Central heating with thermostatic radiator valves set to deliver a steady 19–20°c in lived-in rooms.
• Thick wool throws or proper thermal curtains over window areas to tame cold downdraughts. Do not cover electric heaters.
• Draught excluders for external doors and letterboxes to stop icy infiltration at floor level.
• A simple timer or phone alarm to keep ventilation on schedule.
• An indoor thermometer and, ideally, a humidity meter to track conditions (aim for 40–60% relative humidity).

Avoid unflued gas heaters and portable gas bottles indoors. They add water vapour and raise carbon monoxide risks.

How the method works, step by step

• Pick a target: 19–20°c for main rooms, 17–18°c for bedrooms. Keep the setting constant day and night for at least two weeks.
• Deal with cold glass and walls. Use thermal curtains, clip-on radiator shelves or reflective foil behind radiators on external walls to push warm air across the window line.
• Seal the leaks you can feel, not the ones you need. Fit door baffles and brush strips; keep trickle vents open to prevent stuffiness.
• Ventilate on a clock. Open two opposite windows for ten minutes at around 9am and 4pm. That cross-breeze purges moisture without chilling walls.
• Let air reach hidden corners. Do not pack wardrobes tight against external walls. Leave a small gap behind sofas. Lift clutter off window sills.
• Wipe any morning window condensation with a microfibre cloth. Remove the water, remove the fuel for mould.

Cold surfaces pull moisture. Warm the surfaces and you cut condensation at the source and reduce the energy penalty of damp air.

Why moisture quietly inflates your bill

Moist air stores more latent heat and slows evaporation from skin, which makes rooms feel clammy at the same temperature. Your boiler or heater then runs harder to reach a feeling of comfort. When water soaks into plaster and furniture, those materials act as a heat sink, demanding extra energy every time you turn the heating back on. By holding surfaces at a modest, stable temperature, the home dries, and the system stops fighting against damp mass.

Does it really cut bills by 15–20 per cent?

In many draughty or damp-prone homes, the gains are real. Shaving 15–20 per cent off gas use comes from three effects: fewer reheating peaks, drier air that warms faster, and less heat loss via moisture-driven ventilation. The exact saving depends on your property, insulation and habits.

What does a saving look like in pounds? A gas user burning 12,000 kWh per year who trims 15% cuts 1,800 kWh. At around 7p per kWh, that is roughly £126. A larger family at 18,000 kWh could see near £190. All-electric flats with panel heaters pay far more per kWh; the same 15% cut on 4,000 kWh of winter heating at about 23p per kWh is roughly £138, and heavier users can pass £300. Results vary by insulation, airtightness and how damp the home starts out.

Two weeks is enough to tell: track your meter daily, watch morning windows, and note any drop in relative humidity.

Expert tweaks to make it safer and smarter

• Use thermostatic radiator valves. Set living spaces to 3–4 (about 19–20°c) and bedrooms lower. Avoid opening windows to “thermostat” the house.
• Add radiator fans or clip-on shelves. They push warm air across the room without raising the boiler flow temperature.
• Fit reflective foil behind radiators on external walls. It reduces heat lost to the outside.
• Choose thermal curtains that skim the sill and stop above the radiator. Do not drape fabric directly over electric heaters or block convectors.
• Target a humidity range of 40–60%. If numbers stay high, run a small dehumidifier in the worst room to speed up the dry-out period.
• Cook with lids on, use extractor fans, and keep bathroom doors shut during showers. These small moves prevent large moisture spikes.

Where it works best—and where it struggles

Solid-wall terraces, 1930s semis and rural homes with cool corners tend to benefit the most. The method also pairs well with heat pumps, which already prefer steady, low-temperature operation. In newer, well-insulated flats with mechanical ventilation, a mild overnight setback may beat truly constant heat, because heat loss falls when room temperature drops a touch. Empty homes gain little from background heat unless you face frost risk or mould issues.

A two-week home trial you can run this month

• Day 1: Set all living spaces to 19–20°c. Note the meter readings for gas and electricity. Note indoor humidity morning and evening.
• Days 2–14: Ventilate at 9am and 4pm for ten minutes with opposite windows open. Keep doors closed between zones.
• Each morning: Check windows for condensation and wipe any moisture. Log humidity in one north-facing room.
• Day 14: Record your meter again. Compare with the previous fortnight if you have data. Check if bedrooms smell fresher and walls feel warmer to the touch.

If bills look flat but rooms feel drier and warmer at the same setpoint, you have unlocked comfort gains. If consumption falls and the air clears, keep the routine. If usage rises, your home may already be dry and efficient; switch to a mild day–night setback and keep the ventilation schedule.

Numbers behind the comfort boost

Condensation forms when a surface sits below the dew point of indoor air. By raising wall temperatures a few degrees and dropping humidity by 5–10 percentage points, you move the dew point away from the surface. Less water appears on glass and paint. Less water evaporates later, so the heating system spends fewer kilowatt-hours drying the building fabric. Many households feel comfortable at 19°c with dry air, where they previously chased 21–22°c in damp rooms.

Extra checks to keep you safe and efficient

• Keep flues and room vents clear for boilers and fireplaces. Never block permanent vents for combustion appliances.
• Do not dry laundry directly on electric heaters. Use an airer with a small dehumidifier nearby, or ventilate briskly during drying.
• Bleed radiators and balance the system so each room reaches its set temperature without overshooting.
• If you use prepayment meters, watch the balance daily in the first week. Stable heat spreads usage evenly and avoids sudden top-up shocks.

Warm the mass, move the moisture, seal the draughts you feel. That trio underpins calmer rooms and smaller bills.

Want a quick sense check? Stand by a north-facing wall at shoulder height. If it feels cool and clammy, nudge your valve up a notch and direct warm air across that surface using a slim shelf or fan. If your morning humidity sits above 65% for days, add a temporary dehumidifier while the building dries. If you live with a heat pump, lower the flow temperature and keep the schedule flat; the same method multiplies the pump’s efficiency.

For households facing severe mould, pair this routine with small, targeted upgrades: silicone seals around window frames, brush seals on doors, and a smart plug for bathroom and kitchen extract fans. Those tweaks cost little, they reduce moisture at the source, and they compound the effect of steady, gentle warmth.