I think the simplest way to evaluate this is with a spreadsheet, where you collect the area of each "type" and can plug in numbers for different insulation values for each type, and view the effect on that part and on the total.
i.e if all the windows are the same sort or will be when purchased, you can lump that area & U value.
If there are ...
Maybe this site can help. An easy first step is to open and edit an example. Layers can be switched on/off by a mouse click.
In a few minutes it reveals problems with insulations/moisture or the order of layers.
Toggling between R- value/U- value is done by clicking on the tool icon next to the result.
The screen shot is an example from ...