Why everyone should close their curtains at 7:45pm

With the start of spring, plenty of people turn the heating down a notch but keep it running. Yet there’s a surprisingly big saving to be had from one simple habit: if you close your curtains at the right time, you can keep more warmth in the room and cut your energy bill noticeably - no gadgets required, just good timing and the right fabric.

What’s really happening with the curtain trick

The principle is refreshingly straightforward: during the day, the sun warms your home for free. Windows that get direct sunshine can act like a magnifying glass, letting a lot of energy in. As soon as it gets dark, that advantage flips - the very same glass becomes a route for heat to escape back outside.

Closing the curtains at dusk adds an extra layer of warmth in front of the window - like thin, flexible insulation.

In many places, that moment falls around 19:45 in March. That’s often when the temperature outdoors starts dropping, even though the heat built up during the day is still useful indoors. If curtains and blinds stay open, much of that stored warmth leaks away and the heating has to work harder to compensate.

Why spring is the key moment to lock in warmth

March brings longer days, a higher sun and stronger solar gain. Homes with south- or west-facing windows benefit most. But the heating season isn’t over: nights are still chilly and rooms can cool quickly.

If you consciously “trap” the day’s warmth, you can often drop the heating by one or two settings. The effect is bigger in draughtier, poorly insulated period properties than in newer builds, but even well-insulated flats can see worthwhile gains over several weeks and months.

How much money curtains can actually save

There’s no single figure because it depends on window quality, insulation levels, your heating system and energy prices. Even so, energy advisers consistently point out that closing curtains and blinds strategically can significantly reduce heat loss through windows.

• Windows are often the weakest point in the building envelope.
• Glass transfers heat and cold more quickly than an insulated wall.
• The larger the window area, the more energy you lose without a barrier.

If better heat retention means you can set the heating just 1°C lower in the evening, average heating demand typically drops by about 6%. Over a year, that can add up for a typical household to a mid two-figure to low three-figure sum in euros - achieved purely by changing an evening routine.

Thermal curtains: what they can (and can’t) do

Standard decorative curtains already help, especially if they cover the window area as fully as possible. However, the effect is much stronger with thermal curtains. These are usually made with a thick, multi-layer construction or a special insulating backing.

Thermal curtains act like an extra soft insulation layer in front of the glass - keeping warm air in and blocking cold draughts.

A good-quality pair can cost around €100. That can feel like a noticeable outlay, but it makes more sense when you consider lifespan: if you heat less for several years, many households can earn that cost back.

What to look for when buying thermal curtains for windows

• Fabric thickness: the thicker the material, the better the insulating effect.
• Backing: a thermal coating or lining made from fleece, felt or similar.
• Length: ideally down to just above the floor so cold air can’t flow in underneath.
• Width: at least twice the window width to avoid gaps.
• Hanging height: fit as close above the window as possible so heat doesn’t escape at the top.

How to make the 19:45 trick part of daily life

This is all about consistency. Once you’re used to drawing the curtains at a set time, it becomes automatic. These practical steps make it easier to start:

• Check the time: when does it actually get dark in your area in March? A useful guide is 19:30 to 20:00.
• Set a reminder: use a phone alarm for the first fortnight.
• Choose an order: do a quick burst of ventilation first, then shut the windows, then close the curtains.
• Adjust the heating: after a few days, test whether the room stays stable when you turn the heating down slightly.

After just a few evenings, many people notice the room stays comfortably warm for longer while the outdoor temperature drops.

Summer bonus: a heat shield instead of a heat store

Thermal curtains aren’t just for winter. In summer, the same idea works in reverse: air the home briefly in the morning while the outside air is still cool, then close the windows and draw curtains or blinds during the day. That reduces heat entering the property and helps rooms stay more bearable.

This is particularly useful in loft flats and spaces with large glazed areas, where peak temperatures can be softened significantly. If you usually reach for a portable air conditioner on hot days, smarter curtain management can often reduce how often you need it - saving electricity in the process.

Curtains are only one piece - these combinations work even better

The curtain trick is most effective when paired with other simple measures. For example:

Measure	Benefit in winter	Benefit in summer
Close shutters at night	Further reduces heat loss alongside the curtain	Blocks direct sunlight
Fit draught-proofing strips to window frames	Less draught, more even indoor comfort	Helps stop warm air flowing in from outside
Put down a rug on cold floors	Feet feel warmer, so heating can feel less necessary	More comfortable underfoot, reduced perception of heat

Each action on its own delivers only part of the result, but together they can produce a noticeable comfort upgrade - while also lowering energy costs.

Common mistakes that wipe out the savings

Some habits reduce how well thermal curtains work, including:

• Hiding radiators behind fully closed curtains - heat then struggles to circulate.
• Draping curtains purely as decoration at the sides so large areas of glass are left exposed.
• Leaving windows on the latch while the curtains are closed - warm air streams straight outside.
• Choosing short curtains that stop at the sill.

Ideally, the curtain should end just above the radiator, or be hung in a way that still allows warm air to move into the room. In rented homes where radiators are awkwardly placed, specialist rails or brackets can help hold fabric slightly away from the radiator.

Why this simple trick is so appealing right now

Many households are still feeling the impact of higher energy prices. Major upgrades such as new windows or external wall insulation cost a lot and can’t be done overnight. Being intentional with curtains can seem almost too basic - but it works immediately, takes very little effort and can be done in any home, whether you rent or own.

Once you understand the logic, you often start viewing windows differently: what should you do in the morning, and what works best in the evening? When do you let light and warmth in, and when do you block them? Thermal curtains and a fixed time like 19:45 are simply tools - the real difference comes from a consistent daily routine.