Is that a Garden in your Roof?
Got a green thumb? Gardens are for amateurs; consider applying your talents with plants to your roof. A movement with, uh, roots in Germany is picking up steam in the United States that aims to ameliorate ecological problems from storm water runoff to urban greenhouse warming. A "green roof" or "ecoroof" replaces traditional roofing with a lightweight, living system of soil, compost and vegetation. It's not about looking pretty (although it does) but rather creating a thin, green skin atop your building that gives a little something back to the world—and your pocket book. Apart from local environmental benefits, preliminary evidence suggests green roofs reduce roof maintenance costs and energy use by insulating buildings from extreme temperatures.
More from Newsweek about the American case, we have this as well, up North, in foreign families' homes no doubt, and in a rather modest scale, but I can't find info on it :-( buaaaaaaaa.
A British Website about it:
Here's some info in Spanish about the subject: There's a PDF with techniques and drawings. ;-)