Real ordinary glass does not create mirror images if we loof perpemndicular to it unless there is a reflective or dark background. However, when light strikes it at an angle or we look at it at an angle it could create reflections whether of light or images.
Unless we want to model tinted or shaded glass, I believe using clear acetate would be fine. I have had some experience in building architectural scale buildings and even with a clear acetate, we could simulate the effects of real clear glass windows.
But as I have said, if we want to get that reflective type of effect then leopold's suggestion is a good one. Also if you can get colored transparent tapes, you may also use them.
Good luck.