Green is about Discovery.

The marketplace is about discovery.

Seems strange for a marketer to say this, but if people really want to find green, they will find it. Like they rediscover locally grown produce. Food from a family farm may not be always 100% pesticide free, but its basic goodness is there for all to see. People are starting to FIND these places. The companies don't have to spell everything out, in fact its better they don't: not only is the marketplace about unearthing quarry - Green is about ethics/self discovery, anyway.

Of course marketing is needed. The message up front should be energetic and relevant. But Marketing, to be effective, needs to have symmetry - aligning form and content. Green advertising should appear, and should conserve energy. Show the new features, show the quiet, show the real costs. Don't paint the town green - it's a waste of time. People who need to buy something that is good will catch on, like they catch on to Apple computers.

Punk green marketing notwithstanding, you probably don't have to yell. Let the green recede into the background, or appear in the fine print, where it will be found.