I’m wondering how many members have gone through a similar experience and what conclusions you made.  The window company we intend to order with gave me a heads up to talk with the inspector regarding the lack of an NFRC rating for some of their lines.  I did that, and my inspector and I both completely understand that the windows far exceed code minimum, however the code does require an NFRC U value, which these would not come with.  Salamander has a version of the BluEvolution 82 that does have an NFRC rating and is slightly more expensive, so not a dead-end.  

However, doing a little further digging, there is an option in the code that allows a total UA of the building to be calculated as an alternative.  And there is a table in the code for unrated windows.  Using that table, I can call my triple pane “unrated” windows as a 0.55 (there is no column for triple pane, so I used the double pane column).  Using that 0.55 u value, and the remainder of the assemblies, some basic math tells me I still exceed the UA method for performance, so I should be able to use this assembly without an NFRC rating.  I’m happy to list these tables and codes out if anyone needs.  My code is the 2015 IRC, but I don’t believe these codes changed. A triple pane column would be nice…  A nice inspector might let you use a combined single and double pane column to form a triple. 

So my questions are these – how have others dealt with the lack of an NFRC rating?  And who has done a UA calculation method.  I guess, what sorts of softwares or so on have code officials accepted?  I did my quick calc in excel… but thinking the inspector might want something more official.

I also hope this helps someone else – before you order windows from Europe, it’s worth a conversation with your inspector to see if it will be an issue.