Your confusion is well-merited @josh.greenfield and it is entirely the fault of the “Honeybee_Decompose EP Construction” component. The R-values and U-values that come out of that component are inaccurate for any window construction or material.
I think the full history of it is that @mostapha originally got that component to work well for all opaque constructions but never implemented it correctly for window constructions. I tried to implement it for window constructions at one point but calculating U-values for air gaps between window panes is complex and it was going to be a nightmare to implement it given how messy our code is organized in honeybee-legacy. I have code that calculates the window U-value correctly in the honeybee_energy library now for the upcoming [+] release and I think getting it to work correctly in legacy might be a lost cause at this point. Several times, I have wanted to just remove the R-value and U-value inputs but I know it’s tough to remove functionality that is working correctly for opaque constructions. If you have an opinion on the matter, I am all ears.
But the simple answer is don’t trust the U-values out of the Decompose components whenever it’s a window construction or material. The truth is that the U-value of 0.55 is actually inclusive of some standardized air films that E+ strips out when it interprets simple glazing system materials.