How to reduce heat loss from plastic windows

Windows are an integral part of almost any modern room. Some prefer plastic, while others remain loyal to time-tested wooden ones. With the onset of cold weather, the question of insulation inevitably arises, regardless of whether they are plastic or wooden.

As specialists at PanMarket point out, it is a mistake to think that plastic windows are a panacea for draughts. Of course, they let in less cold air than wooden ones, but quite often there is still a noticeable draught. In this case, it is necessary to determine whether it is a genuine draught or what is known as a "cold spot," where it feels like air is blowing from under the sash, but in reality, warm air is simply moving down along the glass, cooling on its way and accumulating at the bottom. A cold spot can be caused by several factors. The glazing unit itself may not be warm enough, for example, if it is single-chamber and non-energy-saving. In this case, both panes will cool significantly in frosty weather. The only solution is to replace the glazing unit. The radiator may be blocked by the windowsill or simply not working properly. In this case, the issue with the radiator and windowsill must be resolved and the obstruction removed.

You can verify that the issue is not a cold spot by using an open flame, such as a lighter or a candle. If the flame flickers or goes out completely, there is a draught.
If air is leaking along the entire perimeter of the sash, you need to check whether the window is set to winter mode. To do this, open the window, take a sheet of paper and press it against the frame while closing the sash. If you can pull it out without effort, the window is likely in summer mode. To change the operating mode, you need to find all the sash locks (trunnions) and switch them to winter mode with a simple turn. If the window handle becomes harder to turn and the paper no longer pulls out easily, the window has been successfully switched to the required mode.

If the windowsill is not installed airtightly, air will leak from underneath it, because the installers may have saved on mounting foam or failed to plaster the external joint. In this case, you will either have to reinstall the windowsill or additionally treat the joint under the windowsill with sealant.
If more than five years have passed since the window was installed, air may be leaking from the reveals. This is caused by the partial degradation of the mounting joint filler (mounting foam that has not stood the test of time). In this case, you will have to remove all the reveals, refill the frame perimeter with foam, and carefully reinstall the same reveals.

Air may also leak from the junction between the frame and the mullion, which divides the window into sections. The cause is a poor-quality product; there is a gap between the frame and the mullion that should not be there. In this case, you will need to use a high-quality sealant to fill the existing gap.
Air may leak from under the hardware – the handle or hinges. The frame is hollow inside, so cold air from outside enters the frame through any hole on the exterior side of the window, for example from a thermometer, and then seeps into the room through the holes for the handles or hinges. This is resolved by sealing the external holes.

Air may leak from under the window seal. This occurs due to the drying out and partial degradation of the seal. It is resolved by tightening the sash pressure. If that does not help, the seal needs to be replaced.
When sealing windows, do not forget that air circulation within the room is still necessary, and it is important to ventilate the room slightly, even in the harshest frost.