Well, I have to admit, my own, fitted in a kitchen / diner / living space of approx 40 sq metres, "does" suffer from condensation on lower part of frames. Now I appreciate that the relative humidity in this space can sometimes be above what might be ideal, but the level of condensation when it's very cold outside is quite startling. I have been pretty disappointed tbh.
I have wondered whether the construction at the openings was adequate. It seems it may not be.
The structure is cavity wall, of brick outer, 30mm clear cavity, 75mm pir and aerated block inner skin, with dabbed plasterboard and skim. The aerated blocks were returned at openings for window / door, with 30mm pir sealing cavity.
I did question whether this was a smart choice and was assured it caused no issues using thermally broken aluminium framed products.
That might have been utter bollocks, but I was unsure what to push for as an alternative.
I appreciate that the standard of the above is not as good as it could be, and the initial plan was for wider cavity and concrete block internally, but this changed for reasons I wont go into.
I haven't been thrilled with the performance of the Reynaers product on a thermal basis though. Frames feel freezing cold when it's very cold outside.