@arraxxon and rutra,

that beeing true its a very fast solution for me when I have an architect sitting next to me just wanting to have the shadows lighter :-)

I dont always have the time to fiddle around with all the settings. I have tried raising gain and then the shadow side on the object went lighter but the shadow in the ground didnt. When raising the sky dome gain the shadows on the ground went lighter but also the whole image and it looked washed out and flat. So I was quite happy with this quick fix solution for now.

But then again I very much appreciate the other strategies for the future. I still have so much to learn :-)