Hi, I replied on your other thread before I saw this one, so I'll post it here to:
"For starters, make sure the vray lights at the windows have 'sky portal' checked; and, the lights by the windows are meant to guide light through, that's why sky portal is checked. So, you'll need to have a light like gray dome or gray sun outside the building. Also, from all the jagged edges, materials and look of your render, the fray settings need to be optimized for your scene. To know more about your gray render settings, you should post a screen shot of the render settings.
please post the render setting for a further look."