Green Roofs

Green Roofs for a Healthy Monaco  - This photo was provide by Ben Visbeek at Flickr.

A green roof or eco-roof is a roof of a building that is partially or completely covered with vegetation and soil, or a growing medium, planted over a waterproofing membrane. The term "green roof" may also be used to indicate roofs that utilize some form of "green" technology, such as solar panels or a photovoltaic module. Green roofs are also referred to as eco-roofs, vegetated roofs and living roofs.

Green roofs are used to:

* Provide amenity space for building users — in effect replacing a yard or patio
* Grow fruits, vegetables, and flowers
* Reduce heating (by adding mass and thermal resistance value) and cooling (by evaporative cooling) loads on a building — especially if it is glassed in so as to act as a terrarium and passive solar heat reservoir
* Reduce the urban heat island effect
* Increase roof life span
* Reduce storm water run off 
* Filter pollutants and CO2 out of the air 
* Filter pollutants and heavy metals out of rainwater
* Increase wildlife habitat in built-up areas
source: Wikipedia