New construction - window U-values vs. costs

Hello everyone,

we are building a single-family house (140 sqm, kfw70) and our windows are to be installed with a u-value of 0.97 (glass 0.6). We have relatively large window areas and are wondering what a better u-value would bring us in terms of heating costs.

We have an offer (approx. 1.5k) for better insulated windows with a u-value of 0.81 (glass also 0.6). In your opinion, would it be worth installing the better windows? I am not sure when it would pay off or if it would even have a noticeable effect on the heating costs.

I would be grateful for a few tips / opinions.
Lacos

....we have an offer (approx. 1,500) for better insulated windows with a U-value of 0.81 (glass also 0.6). In your opinion, would it be worth installing the better windows?

Who should be able to answer that reliably, since not even the actual heating energy demand of the initial variant is known! One-sided "focusing" on the Uw value of windows can, depending on the location and building orientation, also backfire, since a lower Uw value usually also worsens the g-value! This more or less clearly restricts the use of energy gains through transparent components during the predominant transition period (partial load case).

best regards