How to Switch Tilt-and-Turn Windows to Winter Mode and Reduce Heating Costs

Most people will recognise the situation: the thermostat reads 21 degrees, the radiators are hot, yet the area around the window feels uncomfortably draughty. It is easy to turn to costly fixes, such as replacement seals or heavy thermal curtains. However, many tilt-and-turn windows already contain a discreet feature that can significantly improve their seal and noticeably reduce heating costs - in seconds, without needing a tradesperson.

Why a window can feel freezing despite a warm thermostat

When a room feels cold near the windows, many people initially blame the glazing. In reality, the cause is often elsewhere: tiny gaps between the sash and the frame allow cold outdoor air to enter while warm indoor air escapes. This can happen even with modern uPVC or aluminium double-glazed windows.

Heating controls and thermostats generally measure the air temperature in the room, rather than the perceived cold around the window. A cold draught along the floor or a cool stream of air beside the wall can make the whole room feel uncomfortable, even when the recorded temperature is perfectly acceptable.

A window sash that does not sit tightly against the frame can increase heating costs by as much as 10 to 15 per cent, without this being immediately noticeable.

The explanation is straightforward physics: materials including uPVC, timber and aluminium expand in summer and contract again in winter. This slightly changes the position of the window sash. As a result, the rubber seal no longer presses as firmly against the frame as intended, creating an invisible gap through which air can pass. Many people interpret this as a “broken window” and immediately consider replacing the window or its seals. In many cases, though, a small mechanical adjustment is enough.

The culprit is at the side: the adjustable locking cam

The key component is hidden in a place that receives very little attention: on the vertical edge of the window sash, where the metal fitting runs. Open the window fully and inspect the edge of the sash closely; you will see several small metal pieces, often cylindrical or mushroom-shaped. These are the locking cams.

Their role is not simply to keep the window closed. When the handle is turned to close the window, they pull the sash towards the frame and compress the rubber seal. What many people do not realise is that the cams on many modern tilt-and-turn windows are mounted eccentrically. In other words, they are not perfectly round and can be turned to alter the contact pressure.

On the front of each cam, you will usually find:

• a small dot;
• a notch or line; or
• a flat marking.

This marking indicates the cam's current position, and therefore how firmly the sash compresses the seal when closed. Installers often hand over windows in a neutral middle setting. That is often sufficient during transitional weather or mild winters, but not necessarily in a sharp cold spell.

With one simple turn, many windows can literally be switched to “winter mode” - with no specialist knowledge required.

A quarter-turn with a major effect: activating winter mode

To increase the contact pressure, all that is required is an adjustment to the position of these cams. It takes only a few steps and normally requires just one standard tool.

Step by step: adjust your window for a tighter seal

Start by opening the window completely. Then check the entire edge of the sash and locate every cam. Depending on the model, there may be two, three or more positioned around the frame. In most cases, you can use:

• a 4 mm Allen key (hex key); or
• small flat-nose pliers if there is no hexagonal fitting.

Proceed as follows:

1. Find the marking on the cam: a dot, line or notch.
2. Insert the Allen key, or carefully grip the cam with the pliers.
3. Turn the cam by around a quarter-turn, so that the marking points towards the seal, in other words towards the room.
4. Repeat this process for every cam on the window.

This increases the pressure with which the sash is pulled against the rubber seal when the window is shut. You can usually tell immediately on closing the handle whether the adjustment has worked: the handle will move slightly more firmly, the window will sit more securely, and the seal will be compressed more tightly.

If the window handle feels marginally tighter after adjustment, the seal is working at the limit of its load - and that is exactly where it insulates best.

Immediately noticeable: fewer draughts, a quieter room and lower bills

Anyone who previously felt a clear draught along the frame will generally notice the difference within minutes. The cold layer of air at floor level disappears, sitting near the window feels less draughty, and the temperature feels more balanced and even.

The small adjustment can also be worthwhile from an energy perspective. Depending on the condition of the seals and the quality of the window, cold-air infiltration can be reduced substantially. In practice, savings of around 10 to 15 per cent on heating costs may be possible when several leaky windows are adjusted. The heating system has to compensate less because warm air is no longer continually escaping.

There is another benefit too: when less air passes through gaps, less noise gets in as well. This can create a noticeably quieter feeling indoors, especially beside busy roads or near railway lines. The greater contact pressure reduces sound waves that would otherwise enter through micro-gaps.

Why winter mode should not be left on all year

Although higher contact pressure is useful during the colder months, it should not be maintained permanently through summer. Rubber seals are flexible, but over time they lose elasticity under continuous pressure. If they remain fully compressed throughout the year, they can become flattened and eventually fail to spring back properly.

It is therefore worth adopting a simple routine:

• Switch all windows to winter mode in late autumn.
• In spring, move the cams back slightly, with the marking in the middle position or facing a little outwards.
• Take the opportunity to wipe the seals clean with a damp cloth.

This seasonal adjustment extends the lifespan of the seals and helps the windows remain easy to open and close. Keeping the pressure too high all year can also place greater strain on the fittings, which is another reason to loosen them again in summer.

More simple ways to improve warmth and comfort around windows

The hidden adjustment mechanism is a powerful option, but a few additional measures can improve comfort further without straining the budget:

• Check the seals: If there are visible cracks, or the rubber feels hard and brittle, replacement is worthwhile in the long term.
• Maintain the seals: Apply a small amount of silicone care product once a year to keep them supple.
• Oil the fittings: Treat hinges and moving parts with a drop of machine oil, so that the handle remains easy to operate even with greater pressure.
• Keep the windowsill clear: Tall plants or decorative objects can obstruct air circulation and intensify cold spots.

People living in older properties with simple timber windows will often benefit less from this adjustment, as older fittings do not always offer this function. In those cases, draught excluders, self-adhesive foam seals or targeted replacement of the most problematic windows can help.

How the trick makes a difference in everyday life

A typical example is a rented flat with three large windows in the living room. The thermostat consistently shows 21 degrees, but the residents feel cold on the sofa in the evening, particularly when wind is pressing against the façade. Once the locking cams have been adjusted, the cold sensation at floor level disappears, the heating comes on less frequently, and the living space can be used more evenly as a warm area.

The effect is especially apparent in rooms with laminate or tiled floors because cold air settles at floor level. Anyone with children playing on a rug will quickly notice whether a draught is still present. A brief adjustment to the fittings can achieve more here than wearing a thicker jumper.

Many homeowners already know to bleed their radiators every year before the main heating season begins. It makes just as much sense to check the windows for winter mode at the same time. It takes only a few minutes per window, yet can have a positive effect throughout the entire heating season.