Why Closing Roller Shutters at 6 pm Can Cost You Money in March

Yet in March, that reflex can cost you real money.

More and more households across Europe are timing their heating habits around the clock as well as electricity and gas prices. One seemingly harmless routine is now under scrutiny: lowering the roller shutters as early as 6 pm. What was once seen as a reliable way to retain warmth can become a problem in March. Closing them too soon may block free solar heat and, without you noticing, push up heating costs.

Why the 6 pm rule can backfire in March

In the depths of winter, shutting roller shutters early seems perfectly sensible. It gets dark quickly, outdoor temperatures drop sharply, and every extra barrier between the home and the cold helps. Many people have turned this into an automatic routine: “6 pm, shutters down.”

That habit is no longer as suitable in March. Days are longer, the sun is higher in the sky, and it can still provide a noticeable amount of heat from the afternoon onwards, particularly on south- and west-facing façades. Anyone who blocks out all light at 6 pm is cutting off a free source of heating.

“People who close their roller shutters too early in March often forgo several hours of free solar heat and risk higher heating costs.”

There is also a psychological aspect. If the home becomes dark early, lights are more likely to be switched on, people slip into “evening mode” sooner, and the thermostat may be turned up more generously. The supposed money-saving measure can therefore have the opposite effect.

How much heat do windows really lose?

Windows remain a weak point in a building’s thermal envelope. In poorly insulated homes, around 10 to 15 per cent of heating heat escapes through them; in individual cases involving many old windows, this can rise to as much as a quarter of total heat losses. Authorities such as the French environment agency ADEME point out that closed roller shutters can substantially reduce heat loss through the glazed area, by up to around 60 per cent across the window surface.

The explanation is straightforward: an air layer forms between the glass and the shutter. This acts as an additional insulating layer. The glazing feels less cold, draughts are reduced, and room temperatures feel more even. As a result, some households can manage with the thermostat set half to one degree lower.

For households spending roughly €1,200 a year on heating, consistent use of roller shutters can save approximately €40 to €80, depending on the condition of the property. Savings can be even greater in very outdated buildings with single glazing and effective shutters.

Why March is no longer a time to avoid leaving roller shutters open

Many advice guides say: “Close roller shutters as soon as it gets dark.” In deep winter, that is largely accurate, as outdoor temperatures in many regions have already fallen well below a comfortable indoor level by late afternoon.

In March, however, the balance changes. The sun is considerably stronger, the air cools more slowly in the evening, and south- and west-facing windows in particular can still provide measurable warmth into the early evening. This is why the old 6 pm habit acts like an unwritten ban: sticking to it rigidly stops the home from continuing to warm up for free.

A flexible approach makes far more sense: close the roller shutters when the outdoor temperature is clearly below the indoor temperature you want and there is no longer direct sunshine on the glass - rather than simply because it is “6 pm”.

Typical March scenarios

• Early March in the cold north: The sun is low, dusk arrives early and temperatures are often in single figures. In older, north-facing properties, closing shutters at 5.30 or 6 pm can be worthwhile.
• Mid-March in a mild area with a south-facing façade: The sun may warm the living room until 6.30 or 7 pm. Closing everything at 6 pm effectively switches off the free heating source at the window.
• Late March after the clocks go forward: Daylight lasts noticeably longer, with evening sun potentially continuing beyond 7 pm. A fixed time is then unlikely to be appropriate.

How to find the ideal time to close your roller shutters

The most dependable principle is to watch the thermometer and the position of the sun rather than the clock. Ask yourself two questions:

• Is the outdoor temperature clearly below the desired room temperature, for example 12°C outside and 19°C indoors?
• Is direct sunlight still falling on the window, or has it gone?

Only when the answer is “clearly colder outside, with no more sun” does closing the shutters offer its greatest benefit. At that point, the insulating air layer helps retain indoor warmth without requiring you to turn up the thermostat.

“For every degree the thermostat is lowered, heating energy demand falls by roughly 7 to 8 per cent. Even saving just half a degree through smart roller-shutter management will be noticeable on the bill.”

The orientation of the windows is another key consideration:

• North- and east-facing windows: These usually receive little direct sunshine in March. A fairly fixed closing period between 5.30 and 6 pm can make sense, particularly in older buildings.
• South- and west-facing windows: These sides benefit most from afternoon and evening sun. It is better to wait until the sun has fully disappeared - often between 6.30 and 7 pm.

Modern technology can take on some of the work

Anyone operating roller shutters by hand can easily fall into old routines. Motorised shutters and smart controls offer greater flexibility. Many systems can be programmed to close earlier in deep winter and progressively later in March, adjusted for the direction the windows face and the type of room.

One possible schedule is:

Month	North/east side	South/west side
January	around 5 pm	around 5.30 pm
February	around 5.30 pm	around 6 pm
March	around 6 pm	6.30–7 pm (depending on sunshine)

These time windows do not replace looking outside, but they offer a useful starting point, especially when nobody wants to adjust the shutters manually every evening.

What roller-shutter timing has to do with your wellbeing

In discussions about heating costs, it is easy to overlook that daylight is an important influence on mood and sleep patterns. In March, many people welcome the return of lighter evenings. Consistently darkening the home at 6 pm deprives them of this small sign of spring.

Studies show that more light in the early evening can help stabilise the body clock. People feel more active, get through the evening after work more easily, and cabin fever also eases - an issue that mattered particularly when working from home. Closing roller shutters later therefore makes use not only of solar heat, but also of additional natural light.

Practical everyday examples

• Living room with a large west-facing glazed frontage: Wait to close the roller shutters until the sun is no longer shining directly into the room and it is clearly cooler outside. Until then, let the sun contribute to the heating.
• North-facing bedroom: Here, light matters less than quiet and warmth. On cold days, 6 pm can be appropriate, particularly in older homes.
• Children’s bedroom: Light and sleep are closely linked in this room. Time the shutters so that some evening light can still come through the curtains, while the room does not become cold.

When closing early still makes sense

Despite the drawbacks of a rigid 6 pm rule, an early closing time remains the best option in some circumstances: in older properties with draughty windows, in ground-floor flats exposed to passers-by looking in, or on particularly windy days. Anyone regularly feeling cold beside a window in the evening should lower the shutters sooner rather than later.

Over the longer term, it is worth considering the wider set-up: airtight windows, adjustable ventilation, well-fitted seals and suitable roller shutters all work together. The better the thermal envelope, the more flexible you can be with the timing - and the more the March sun can deliver its benefit.

Ultimately, there is no absolute ban and no magic time. Paying attention to the thermometer, the sky and your own sense of warmth will usually lead to a better decision than any automatic 6 pm reflex.