Lighting in renders

[LeeElston]

A couple of rendering issues... In shaded rendering my model when viewed from a disatnce appears fine and bright, but as I zoom in it gets very dark so you cant see the wall finishes. 

Also, in the elevation viewport, the texture of the render is invisible and I just see the blockwork texture behind the render in the wall components. Red x is the same wall on all images.

All walls are set to render by component

Any advice gratefully received

[Tom W.]

It looks from the images that you might have z-fighting going on: doubled-up geometry. I'd check that first