Windows look awful / too dark

[koenvdw]

Hi

In my new project I'm using a vray dome light in combination with an HDRI. I'm pretty pleased with it accept with the windows.

Below you can see my render. The windows are too dark.How can I solve this?
Do I put some lights in the building, do I have to change the angle of the sun so the glass reflects more, do I have to use double glazing, do I lower the transparency...
I did put a 180° background behind the camera to hopefully catch some reflection, but it didn't work.

[pbacot]

What does your interior look like? Perhaps it is not reflecting the light inside. Is the glass reflective? I don't see any sign of reflections. Just suggestions.

[koenvdw]

Interior is empty except the curtains. I dont want the interior to show a lot, because it's an exterior render.
The material is the Translucent_Glass_Gray from sketchup with a reflective and refractive layer added in vray materials.

[pbacot]

I don't use V-ray but if your interior is a black hole, V-ray might be showing it that way. Maybe it just needs some white surfaces.

[rspierenburg]

I typically add a very subtle bump (wavey) to my window glass to simulate the inconsistency in typical window glass. That might add some reflection to the view as well.

[koenvdw]

@pbacot
It was indeed a black hole. The whole building was a group and I accidentally painted the whole group with a dark material. So all the standard (white) material was replaced.

I also replaced the glass material with another one.

I'm pretty happy with the result now.