I've spoken to several Green startups that are committed to providing truly green products, but few have the cash to invest in things like Green office space, green vehicles, etc.  Especially at the earliest stage of the game.  Foundation Capital in Menlo Park puts many of it's Green start-ups in the headquarters building, which they aim to have LEED's certification for it.

Practicing what the sell, I like it.
Foundation Aims to Be LEED-Certified VC - Earth2Tech