Set about building all the glazed walls as geometry to see how this works. The alternative is to use textures for them all and both have appeal in different ways. I still have plenty to learn about map logic in hammer (what should be grouped with what, with what settings - func_detail is proving a life saver, but interacting with these settings is weird. Viewing the settings and working in groups is messy in this area).
Compared to the place-holder texture walls I has in place until now, the new model looks great. It doesnt have the multi-layered transparency artifacts that were there previously and the frames and glass work together beautifully.
Here are a few shots of the current state first showing the main entrance, then a shot in the light-workshop with the 3D print room in the centre, then a shot from inside the computer room looking back out to the lockers: