Green nanotechnology involves two separate but related goals on the one hand the remarkable characteristics possible at the nanoscale promise myriad ways of making existing products and processes safer and more sustainable on the other researchers are increasingly finding ways to render nanotechnology less toxic throughout its life cycle. Green roofs what are green roofs and the various types of green roofs environmental gains of nanotechnology and nanomaterials may be offset by nanotechnology manufacturing processes studies indicate that nanotechnology based water treatment techniques will be more economical more durable and more efficient than the present traditional ones. Green nanotechnology has two goals producing nanomaterials and products without harming the environment or human health and producing nanoproducts that provide solutions to environmental problems