If your looking for the more hard science, evidence based side, there is some out there. Its not as easy to find as you might think, but as with most research articles, if you find one, between looking at what they cite and who cites them, you get a quickly growing research stack pretty quickly. If you can find case study articles out of Europe, they seemingly have a head start on green infrastructure, especially Germany.
I THINK West8 in Rotterdam has done some work in the area, you could also look at their portfolio for some info.