Glass reflection effect

Hi guys,

I have a question about the texture setting "Use global environment map as refelction" in the MCX. I would like to use this setting for large glass areas. However, the effect is too violent for me. Many of the window panes appear in complete white (see picture below).
So my question is: Is there a way to reduce the effect a bit (to make it more or less transparent), so that the real color of the window surface remains despite the reflection? I haven't been able to find anything so far.
I would be happy about a good tip

Cheers Manfred

This can be adjusted in whichever map you use for reflections -- specular alpha, or inverse diffuse alpha. I normally use inverse diffuse alpha, which means my reflective surfaces have a very light grey alpha, where black is full-on reflective.