Simplifying window panels

Hi all, 

I am trying to create a script to simplity window panes, i.e. transforming them from a "box of 6 faces" to a single surface, taking only the exterior surface and ruling out the rest. I would do this by: 

1. Decomposing the panes and selecting the two largest faces to rule out the edges. 

2. Out of the two remaining surfaces per pane select only the one that is furthest from a point in the middle of the building point (outer pane). 

The problem is that I don't know how how to trace back the correspondence between the area values and the faces.

I believe this should be quite easy to solve. Can someone help me? Thanks in advance. I attach the rhino and grasshopper files.

Alejandro