Sound insulation and thermal insulation specifications for windows with "from-to"?

Hello dear forum community!

We have decided on Internorm KF 410 windows – on the website a sound insulation value of "34 to 45 dB" is given, and for thermal insulation it states "Uw up to 0.62". I am a bit confused about this. Either it insulates sound by 45 dB or it doesn’t?

How exactly is this to be understood?

On the delivered windows it says:
Sound insulation: 34 dB
Thermal transmittance coefficient: 0.77 W/m²K

It would be great if someone here had some information :)

Thanks & best regards

Windows are individually configured. In the standard version, they insulate 34db. You can get up to 45db for an additional charge. This is achieved with thicker glass, which then vibrates less.

The same applies to the other attributes as well. This also applies to thermal insulation.

Or, for example, burglar resistance is possible up to RC2. However, the standard is probably RC0.

You apparently received the standard version. I assume that you also ordered it.

Thank you for the information! It would of course have been good to know that when ordering. The dealer only said that the Internorm window is significantly better because of higher sound insulation and lower U-value.

The dealer only said that the Internorm window is significantly better because of higher sound insulation and lower U-value.

Almost every salesperson claims that about their product. As already explained, the sound insulation values depend, among other things, on the glass thickness, which in turn depends on the profile depth of the window. The U-value depends, among other things, on the cavity between the panes. The thicker the panes, the smaller the cavity. In laminated safety glass (VSG), for example, an additional film is incorporated, which also requires space; therefore, depending on the window size, the U-value in windows with VSG panes can also change slightly.

Thank you for the explanation! What is the U-value of the window actually? There are no more specifications on the window itself, only this thermal transmittance coefficient of 0.77 W/m²K

What is stated in the contract can be checked by comparing the data on the sticker on the panes at the time of delivery.

If a window consists of several panes (e.g., in floor-to-ceiling windows without a railing, but with laminated safety glass in the lower area), the panes can have different Ug values.

The Uw value is important because it is composed of: Uw (Window) = Ug (Glass) + Uf (Frame)