For fixed windows, I usually use 3 pane low e purchased from a glass shop and case them out myself. There’s no NFRC rating. So Energy Star says for that situation refer to 2013 ASHRAE Fundamentals, Chapter 15 Table 4. I have 2017 which is likely not different, and I don’t understand what I’m looking at. The U values are in a 1 to 2 range. I was expecting to see .18 to .25 or similar.

Are unrated windows really subject to a huge U value penalty or am I supposed to do some math to arrive at a U value that makes sense (to me)?