window transmittance

[Anonymous]

How can I change the window transmittance in Revit? Because there are already some set window but I'd like to put mine custom window U= 1.1. 
Thanks!

[ToanDN]

The value is based on the Analytical Construction assigned to the Window type.

You could edit the right Constructions.xml file (for example: c:\Program Files\Autodesk\Revit 2017\en-US\Constructions.xml).

Reality check:  I am not a scientist so I have to ask what kind of material gives you 1.1 transmittance value?  Isn't 1 the maximum you can get, which is basically no material.