It's difficult to tell whether they are standing in an interior or exterior space. A quick fix would be to add more reflection to the glass. Also, you might consider making the primary light source brighter, or making the secondary light sources less bright. The people seem to be facing the primary light source, but the building they are looking at seems to be lit on the oppisite side by an equally bright light. Finally, you might want to add lights in the dark spaces that seem to surround the people.(Or turn them on if they are already there) Make the large panels at the left of the image a focus point for the lighting--they are lost in this image. I'm sorry to be so critical, and you DO have an interesting mood in this image. Good luck with the project.

Some good points. Thanks for being so critical! The people (and their shadows and reflections)have been added in photoshop so thats the reason they look a bit out of place in terms of lighting- it's quite typical for architectural visualisations to have people such as these to give a sense of scale. I will add more reflection to the glass but I can't really adjust the brightness since the project it all about demonstrating natural lighting simulation...there are other renders at different times of the day...I could just turn the lights on above to brighten up the artium a little!