A blast of icy air creeping in near the window even though it’s closed. This phenomenon affects thousands of households every winter, without them knowing that a solution already exists on their window frames. This setting is called winter mode, and it lies dormant, ignored, on a good portion of PVC and double-glazed windows installed in France.
The principle is simple: an eccentric screw, hidden on the edge of the opening panel, allows you to increase the pressure exerted on the weatherstrip. As a result, the window closes tighter against its frame and blocks more air infiltration. It’s free, takes five minutes, and yet almost nobody touches it.
What is winter mode on windows and why is it so little-known?
Winter mode on windows refers to a joint compression setting built into many window frames from the manufacturing stage. Manufacturers install it in anticipation of temperature variations, but rarely inform buyers about it. The seller explains the color of the profile, the warranty, sometimes the glazing, but forgets this technical detail that changes the seal quality daily.
Concretely, each closing point on the window (the small metal rollers visible on the edge) can be adjusted to several positions. In summer position, the pressure is lighter, which makes opening easier and limits wear on the joints. In winter position, the pressure increases, the joint is pressed harder against the frame, and cold air has much more difficulty infiltrating.
Why your windows let cold air in even when closed
A closed window is not necessarily a sealed window. Over time, the weatherstrip becomes compressed, hardens, or loses its elasticity—a problem that this quick test to check if a window seal still closes properly can actually detect in just a few seconds. This joint wear phenomenon is intensified by the hot-cold cycles of the seasons, and it only takes a gap of a few millimeters for air infiltration to become noticeable, especially in strong wind.
These heat losses are one of the reasons why some homes are classified as thermal sieves, even when double-glazed windows are recent. The glazing insulates well, but if the compression on the joint is insufficient, air continues to circulate around the frame. The condensation that appears on the windows in the morning is often a signal of this imperfect seal.
How to activate winter mode on your windows: the tutorial
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another plant.
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First check if your windows are compatible
Not all window frames have this adjustment. You need to open the window and observe the edge of the opening panel, where the small metal rollers called cams or hinges are located. If they have a slightly oval shape with a marker (dot, line, or notch), this is a sign that seasonal adjustment is possible. Recent PVC windows and some aluminum models are often equipped with this, unlike older or budget window frames.
Compression adjustment in three steps
The procedure requires only an Allen key or flat pliers, depending on the model of eccentric screws.
- Open the window and locate each roller on the edge of the opening panel, typically three to five per window.
- Turn each eccentric screw in the direction indicated for winter (often marked by a dot or arrow), turning all the rollers in the same direction to maintain even pressure.
- Close the window and test the resistance of the window handle: it should be firmer to close than before, a sign that compression has increased.
The paper sheet test
As explained in our article on the paper sheet test to spot windows that let cold air in, insert a sheet of paper between the opening panel and the frame, then close the window.
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This feature requires the Plantalya app. Scan any plant instantly with your camera!
Scan Your Plant — Download Free AppIf the paper slides easily once the handle is locked, the seal is insufficient. Repeat the test at several points on the frame after adjustment to verify that pressure is even throughout.
Real gains: comfort, insulation, and savings on your bills
The most immediate benefit concerns the thermal comfort felt near the windows. No more that little draft forcing you to move the sofa or desk away. The overall thermal insulation of the home improves slightly, without replacing any window frames, which remains the least expensive solution to limit heat loss around openings.
On heating bills, the effect depends on the number of windows involved and their initial condition (also remember to check radiators before turning them back on after several months of downtime through this guide on radiators to check before their first restart). In a home where several openings had a seal defect, the drop can be felt in monthly consumption. This isn’t a step that transforms a thermal sieve into a low-consumption home, but it is a free adjustment that directly addresses air infiltration, where standard insulation doesn’t intervene.
Never kill
another plant.
Take a photo: the app names the species, spots the problem and tells you exactly what to do.
Warning: mistakes to avoid and professional advice
Some window installers advise against leaving winter mode activated all year round. Permanent compression accelerates joint wear and can eventually weaken the closing of the opening panel. The ideal approach is to alternate: winter mode during the cold season, return to summer mode when temperatures rise, to preserve the flexibility of the weatherstrip over time.
Another point to watch out for: never force an eccentric screw that resists abnormally. A stuck roller or poorly maintained old window frame can break under pressure. A little silicone grease on the rotation points often makes the adjustment easier; otherwise, it’s better to call a professional rather than damage the closing mechanism. This adjustment remains a useful complement to proper window maintenance, not a substitute for an overly worn seal that will eventually need to be replaced.
