U Value for existing windows

Alkers

We are looking at getting some retrofit work done via an SEAI scheme.
We bought the house two 1/2 years ago and the rear of the house was extended in 2012. The extension has a window and french doors, both of which are triple glazed.
The SEAI are saying that unless we can produce U-value certificates for these windows, that we would have to replace them in order to avail of any grants for window replacement for the rest of the house. We have no contact with the previous owners and don't know who installed the windows. I've identified the glass manufacturer via some barely legible frosting on the internal pane but they weren't able to match the numbers I gave them to any of their records (it's possible that I missed a few digits as it's extremely hard to read).
Any advice as to what I can do in this situation? Is it possible to determine the U-value of a window once installed?

sydthebeat

Ultimately no its not.

You need the order number from the window, and then to match that order number from the manufacturer, and for them to then supply the cert.