UK Households Urged to Follow 4pm ‘Curtain and Window’ Rule as Energy Firms Warn of Higher Winter Bills

As temperatures drop and sunset creeps towards 4pm, millions of UK households are being urged to close windows and draw curtains earlier in the afternoon – or risk paying more than they expect for winter energy bills.

In the last few days, Octopus Energy, British Gas, and consumer champion Martin Lewis have all been linked to fresh advice about a so‑called “4pm rule” and the “right time” to use your curtains and windows to trap heat. Coverage in outlets including the Mirror, BirminghamLive (syndicated via Yahoo News) and the Daily Record has pushed these tips into the spotlight just as bills remain far higher than before the energy crisis. ^[1]

At the same time, Ofgem’s price cap means a typical dual‑fuel household is paying around £1,755 a year between 1 October and 31 December 2025, with a small rise to £1,758 from January 2026 already confirmed. ^[2] Energy debt across Britain has ballooned to around £4.4 billion, prompting the regulator to work on a debt relief scheme. ^[3]

Against that backdrop, even “small” behavioural tweaks – like what you do at 4pm – suddenly matter.

Why are we hearing about the 4pm rule now?

Over the last week:

Mirror Money reported that Octopus Energy is backing Martin Lewis’ “4pm rule” as the weather turns colder, encouraging households to use windows and curtains tactically to keep heat in. ^[4]
BirminghamLive, in an article syndicated by Yahoo News, ran the headline that “UK households [are] told to close windows from 4pm or face an ‘unexpected bill’”, highlighting British Gas advice on avoiding heat loss during peak heating times. ^[5]
The Daily Record picked up British Gas guidance that bills can be reduced by opening and closing curtains at the “right time”, again stressing the importance of timing rather than just having curtains. ^[6]

All three pieces revolve around the same idea:

You lose a huge amount of heat through your windows – especially after dark – so what you do with your curtains and windows around 4pm can make a real difference.

That advice lands at a tricky moment. The October–December 2025 price cap is higher than the same period last year, and standing charges are still painfully elevated – around 53.68p/day for electricity and 34.03p/day for gas, according to recent coverage of Ofgem data. ^[7]

So while wholesale prices are no longer at record peaks, many households are still struggling. Energy firms and consumer experts are therefore leaning hard on low‑cost or free behavioural changes.

What exactly is Martin Lewis’ 4pm rule?

The so‑called “4pm rule” comes from advice Martin Lewis gave on his ITV money show and has recently been re‑circulated by his team and lifestyle sites such as Ideal Home. ^[8]

In plain English, the rule is:

Keep curtains open while the sun is out
- Sunlight is free heating. South‑ and west‑facing windows especially can warm rooms during late morning and early afternoon.
Around sunset – roughly 4pm in late November – close your curtains and windows
- As soon as it gets dark, those same panes become cold surfaces that leak heat. Closing thick curtains and properly shutting windows turns them into an extra layer of insulation.
Time this with your heating schedule
- Many households put the heating on for a couple of hours in the early evening. If your curtains are already closed at (or just before) that time, more of the heat stays inside for longer.

Lewis has summed it up along the lines of:

When the sun is shining, you want curtains open to let heat in. Once it’s dark, close them to keep the heat in. ^[9]

It’s not a magic fix, but it’s a no‑cost habit – which is why suppliers like Octopus are now actively amplifying it.

Why 4pm matters so much in late November

By 25 November, most of the UK sees sunset a little after 4pm. That’s exactly when:

Daytime solar warmth is dropping off.
Many people are arriving home from work or the school run.
Thermostats start calling for heat as indoor temperatures fall.

If your windows are still slightly open “for fresh air” or your curtains are wide open at that moment, your boiler or electric heater has to work harder to compensate. That’s the logic behind headlines warning that households who don’t close windows from 4pm could face an “unexpected” or higher‑than‑planned bill. ^[10]

Energy‑efficiency data backs up the concern:

The Energy Saving Trust has previously estimated that windows are responsible for around 18–20% of heat loss in the average UK home. ^[11]
Research for the US Department of Energy finds that well‑fitted insulated blinds or cellular shades can cut heat loss through windows by around 40%, translating to about 10% lower heating energy use. ^[12]

The exact numbers will vary by property, but the direction of travel is clear: once it’s dark, bare glass = lost money.

What is British Gas advising about curtains and “the right time”?

The Daily Record article that’s been widely shared focuses on British Gas advice about using curtains at the “right time” to reduce bills, and on adjusting routines to cut waste. ^[13]

On its own website, British Gas says: ^[14]

Heating and hot water make up more than half of a typical energy bill.
Turning your thermostat down by 1°C could save up to 10% on heating usage.
To reduce heat loss, you should draught‑proof your home and “close your blinds and curtains” during colder winter months to keep heat in.

In other words, the supplier is telling customers to:

Use curtains and blinds actively, not just as decoration.
Adapt them to the weather each day – don’t leave them half‑open out of habit.
Pair that with small thermostat tweaks and other routine changes (washing at 30°C, limiting tumble‑dryer use, etc.).

The viral “right time” message being shared via social posts comes down to the same principle as the 4pm rule:

Open when the sun can help you, closed when it can’t.

So what are Yahoo and BirminghamLive saying about closing windows from 4pm?

Because of access limits, we only have the summary rather than the full Yahoo News article, but the key points are clear from syndicated snippets and social posts: ^[15]

The piece reports that UK households are being told to close windows from 4pm or risk an “unexpected bill”.
It links that warning to British Gas guidance, stressing that relying only on curtains isn’t enough if windows are still open or on vent.
The article also mentions making the most of “free” energy – meaning the warmth from daylight and your heating while it’s already on, rather than letting it escape outdoors.

Put simply: if your heating kicks in while windows are cracked open, you’re literally paying to warm the street.

The messaging ties in neatly with British Gas’ broader set of energy‑saving tips and schemes like PeakSave, which reward customers for shifting usage to cheaper or greener times of day. ^[16]

How much difference can a 4pm routine really make?

Every home is different, but experts and official guidance suggest the cumulative impact can be significant, especially over a whole winter.

1. Reducing heat loss through glass

Combining data from UK‑ and US‑based energy bodies: ^[17]

Windows can account for around a fifth of heat loss in a typical home.
Properly insulated window coverings can cut that loss by up to 40%, roughly a 10% reduction in heating energy.

If your heating accounts for, say, £1,000 of your annual bill, a 10% reduction is £100 a year – all from habits and better window coverings.

2. Working with the current price cap

With the October–December 2025 price cap at £1,755 for a typical dual‑fuel direct debit household and £1,758 from January, even shaving 5–10% off usage is worth real cash. ^[18]

A modest 7% saving on a £1,755 usage‑based bill is £123.
For many families, that’s a December food shop, a month of council tax, or a chunk of rent.

3. Helping with energy debt

Ofgem has highlighted that household energy debt is adding about £52 to the average annual bill through costs baked into the cap, and is working on a scheme that could write off around £500m of that debt. ^[19]

Small efficiency gains don’t remove that pressure, but they reduce the chance you add to that debt this winter.

A practical 4pm energy‑saving routine you can copy

Here’s a simple, no‑cost routine inspired by the advice reported from Octopus Energy, British Gas and Martin Lewis, plus official energy‑efficiency guidance:

Morning to mid‑afternoon

Open curtains wide in all lived‑in rooms – especially south‑ and west‑facing ones.
If it’s not freezing, crack a few windows for 10–15 minutes early in the day for ventilation, then close them fully. Rapid “air dump” ventilation wastes less heat than leaving them ajar all day.

Around 3.30–4.00pm (or about 30 minutes before local sunset)

Shut all windows fully in the rooms you’re going to heat.
Close curtains and blinds fully on those windows – tug them so they sit snugly against the wall where possible.
Check for hidden heat leaks:
- Curtains draped over radiators will block heat – tuck them behind or above if you can.
- Move furniture slightly away from radiators.
Sync with your heating schedule:
- If your heating normally comes on at, say, 4.30–5pm, make sure your window routine is done first.
- Consider turning your thermostat down by 1°C – British Gas and others say this can save around 10% on heating use while still being comfortable for most people. ^[20]

Evening

Keep internal doors closed in rooms you’re not using so the heat stays where you are.
Turn off lights in unused rooms and avoid using multiple high‑draw appliances at once (e.g. oven + tumble dryer + electric heater).

Before bed

If it’s safe to do so in your home, turn the thermostat down another degree or set night‑time temperatures lower.
Don’t completely shut off heating in severe cold if you’re away overnight – Energy Saving Trust guidance warns this can risk frozen pipes – but you can keep it at a minimum setting. ^[21]

Who benefits most – and who needs more than a 4pm rule?

These tips are most effective for:

Homes with reasonably good insulation and double glazing – you’ve already reduced the biggest losses, so behavioural tweaks become more noticeable.
People on standard variable tariffs stuck at the price cap, especially those who heat mainly in the evening.
Smart‑meter households who can visually track the impact of these habits in real time.

However, some households need more than routine changes:

Poorly insulated, damp or very draughty homes – curtains help, but you may still lose a lot of heat. Bigger fixes like draught‑proofing, loft insulation or secondary glazing will have much greater impact.
People on very low incomes or with existing energy debt – you may be eligible for:
- Cold Weather Payments or other targeted support in certain conditions. ^[22]
- Supplier hardship funds or local council support schemes.
Anyone with medical or disability‑related heating needs – always prioritise health and safety over strict bill‑cutting.

If you’re struggling to afford energy at all, most major suppliers and charities urge you to contact your energy company early, as there may be tailored payment plans or grants available. ^[23]

Ventilation, safety and common‑sense caveats

Closing windows and curtains too aggressively can cause other problems if you’re not careful.

Carbon monoxide risk – If you use gas, solid fuel or other combustion appliances, you must maintain adequate ventilation and have working CO alarms. Never block purpose‑built vents.
Condensation and mould – If you notice heavy condensation on windows or walls, you may need short, sharp ventilation bursts (like opening windows wide for 5–10 minutes) even on cold days.
Overheating from portable heaters – Don’t drape curtains or clothes over plug‑in heaters or radiators; follow all safety instructions.

Think of the 4pm rule and British Gas timing tips as guidelines, not absolute laws – apply them sensibly to your own home layout and health needs.

Key takeaways for 25 November 2025

Energy bills are still high: the current price cap leaves a typical household paying about £1,755 a year, rising slightly in January 2026, and energy debt remains a major national issue. ^[24]
Suppliers and experts are pushing low‑cost habits, not just gadgets, to help people cope.
The “4pm rule” backed by Octopus Energy and Martin Lewis essentially means:
- Use the sun during the day
- Close windows and curtains around sunset
- Time your heating to work with that, not against it. ^[25]
British Gas’ “right time” advice on curtains and window coverings fits the same pattern and is consistent with its broader energy‑saving tips. ^[26]
The BirminghamLive/Yahoo coverage about closing windows from 4pm or facing an “unexpected bill” is a warning against accidentally heating the outdoors while prices are still elevated. ^[27]

For most households, a disciplined 4pm routine, better curtain use, and a 1°C thermostat tweak won’t solve everything – but together they can chip away at your bill every single night of this winter.

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