SBF # 24 Energy Star window ratings and NFRC

Did you know that most windows come with an NFRC(national fenestration rating council) sticker that gives you a list of performance values that are not for that actual window?

I found this out because Energy Star requires all windows to have a U(1/R) value of .32 or better(lower).
I have 4 Pella windows with a U value of .33.  I thought that I could improve this with a low E film applied to the inside and began a discussion with my energy mentor Andy Shapiro.  We found out that the number on the sticker is given for a standard window size with the given glass and frame.  The standard size is 2'x4' and the actual window is 29"x50".  So we found the manufacturer of the glass and the specific type and matched that to a frame material in LRBL's Window6 simulation program to give us the .33 that is shown (using the standard size).  Then I changed the window size to what we actually have(29"x50"), which is a bigger ratio of window to frame, meaning the U value will be greater because the glass is more insulative than the frame.  As we expected we ended up with a slightly better U value of .32, which gives us the grade to pass Energy Star. No film needed.
If we also added the film, we would have lowered our SHGC(solar heat gain coefficient), but more drastically improved the U value to below .3.