well… read the Grasshopper notes and found the answer:
We are adding two window groups for this study. The skylight is its own window group which is not dynamic but we’re interested to study its contribution separately. South window is the other window group which has two states: 1. clear, 2. diffuse50
Ensure that window groups are facing outwards. Honeybee flips the surfaces for view matrix calculation internally.
In honeybee the concept of window group is more flexible than window group in Radiance documents. I’m currently renaming them to sources (short for light sources) to make this more obvious.
As you noted above Honeybee keeps the windows looking outwards which is what we need for energy simulation. It then creates a separate file for each window group/light-source for each state and calculates the view and sky matrices for each of them separately. That’s when it flips the direction of the surfaces. You can find them under wgroup folder.
PS: I started this page to clarify the structure of the folder for honeybee[+] daylight simulation. It’s still a work in progress but might be helpful in your case.