hi, my last project.
i am not satisfied with the windowglass. i used vraysun/sky, vrayphyscam and a blue color for refl/refr env. override (rgb 100/154/229)
in post i made some reflections of trees.
c+c to improve the image very welcome
For stuff I did recently I got a plane with a nice sky image on it, put it right in front of the windows and turned it off to gi, shadow cast and receive and camera visibility - lots of detail in the shadows - worth popping out a reflection pass and a multi matte element for the windows too so you can tweak or strengthen the effect in post.
Only other thing I do is make the reflections stronger than they should be by not using fresnel and stick in a falloff map instead - make the dark side about 33% grey and the light side about 80% white - pushes the look a bit.
Or you could just do all the glass in post 
True dat, bit more hassle with mooovees though.
reflection pass + multimatte pass with a channel for the glass material + photoshop screen blending mode 
generally the rules of lighting a stage or a scene specify a lighting direction to be about half opposite of the camera direction. This will produce a stronger illumination/reflectance on a fresnel angle. In your case your lighting is coming from the same direction as your camera, negating all of the fresnel.
Its true your image is missing alot of contrast and being flattened due to your sun angle.
you are totally right. will rerender with your suggestions for the sunposition.
How did you do your hedges and “bush balls”? They look quite good. Are they meshes or displacement or something else?