Green Roof technology is a fast moving science and is associated with Living Wall technology. This is the science of clothing parts of buildings with plants to replace the benefits which are lost through building on green spaces.
Green walls and roofs can be ornamental or productive.
This is an article written for the VGS which gives basic information about Green Roofs.
You can find out more about what is happening in the UK ( and further) from the links below.
From Arch Daily architecture website
Green roofs for healthy cities.
Needs lots more copy and links, needs historical info about the green technologies of the past like cob walls.