Air infiltration for Windows and compliance with IECC 2018 for European windows – GreenBuildingAdvisor

Many deparments of permitting are now requiring compliance with IECC 2018. According to the 2018 International Energy Conservation Code (IECC), the air infiltration requirement for windows is a maximum of 0.3 cubic feet per minute per square foot (cfm/ft²) unless the window is site built. For European windows that are not certified by NFRC, this value is not available so is there a way to still use European windows without NFRC certification in this case?

For U values and SHGC there are tabled standard values that can be use in a Rescheck calculation but I do not think this is the case for air leaks so I do not see a way out from NFRC certification. The problem is that European windows with NFRC certification are a small fraction and are also 15 to 20% more expensive in my experience.