Dear microjungle, I am interested to participate in your contest. #3 and #4 are the initial proposal for you. Subsequent entries will follow. Feedback and suggestions will always welcome.
We'd like to see the blue from our "ecological roof" somewhere. The tree and other elements should be more abstract. We like blocks of color more than actual trees, etc. Overall your #4 is the best so far, but I think it should be a little more simple.
We still think #28 has a shot, but we're not crazy about the font. Can you try something different? We think black-and-brown or black-and-grey might be nice. Also, we tend to like the lower case fonts better (but not always).