August 28, 2013, 01:07:47 pm
How are you setting the windows? Glass Material with high reflection or are you using Planar Reflections?
The amount of Transparency is what allows visibility through the Glass Material (window), so this can be changed at any time, but not as a material animation, that is, it requires to be done manually.
So for photo renders at night you would need to adjust the Transparency (and maybe level of Reflection as well), then do the render, and change back for any day time renders.
For video animation, its easier to make sure the night views have their own clips, then those clips can be rendered separately from the day ones, having changed the Glass Material to suit.
An alternative (note: not tried or tested, just an idea), is to have separate window objects exported and imported. One for daytime, one for nighttime (requires 2 imports). Put each one in its own layer and use the Hide Layer for night windows in the daytime clips. And, Hide Layer for daytime windows in the night clips. This approach means the whole movie can be rendered without manually changing materials and having to merge the separately rendered clips.