That’s still an “underground hype”, but green walls are catching up attention from many people in Europe who see them as a real way to improve our environment, especially within towns and surbubs. The principle is to cover a building wall with a substrate where moss and various plants can take roots, grow up naturally and cover the entire surface of the wall. Expected benefits include: thermal isolation, phonic isolation (up to 16dbA), aesthetic and… depollution, including absorption of air’s CO2. The best green walls benefit from the ambiant air’s humidity and are self-maintaining! More sophisticated ones require a regulated water and nutritive contribution system. Several technical options for the initial structure are available, from steel grids that encapsulate the substrate, to affordable cut felt! Read the Wikipedia entry in English (quite short though) or better the French Wikipedia entry
In french country, peasant do not use anymore this type of isolation because of insects.
Perhaps towns are the good place for this kind of wall???
But Knarf, why were you using it on… your car?