It turns out that it is very important to understand who is the manufacturer of double-glazed windows that you have chosen. I ordered windows for the whole house (3 floors, about 20 windows of different sizes), unfortunately, the double-glazed windows in my windows were from the company "Aerated Concrete". When they came into the house a couple of years later and turned on the heating on the ground floor, they realized what their problem was. Double-glazed windows are either not sealed, or assembled in violation of technical processes. With a strong temperature difference from different sides - !!inside the packages!! condensation forms. It dries out later and forms again. Later, smudges with plaque (most likely fungus) appear and the windows look dirty, with white smudges and plaque, and it's all inside the package, that is, it's impossible to wash and eliminate it. This evil "lottery" worked only on the ground floor on several windows. I feel that when we start heating on the other floors, there will still be "surprises". There is only one solution: Double-glazed windows for replacement! And this is the lion's share of the cost of the entire window + the departure of the windowmaker and his work. Be careful when choosing a package manufacturer! Unfortunately, this plaque is not so clearly visible in the photo. In real life, he is much more "colorful".