Hold a lit candle at various positions close to the window frame. If the flame of the candle flutters a lot, there are definitely wide gaps that allow an exchange of air. If it flutters just a little, the gaps are still wide enough to affect the room temperature. If it flutters only slightly, but it feels considerably cooler close to the window, there are at least small gaps to prevent economic heating or air conditioning.
Try to test the situation at different positions of the window frame. In this way you get a good idea of where the trouble spots are and are able to address it with a suitable self-adhesive tesamoll® sealing profile.
How wide is the gap of your window (mm)?
How long is the gap of your window (m)?
Choose a Region: