Green Roofs have existed for as long as man has here on Planet Earth in one form or fashion.
Today we see the majority of green roof drainage systems created and manufactured from petroleum based chemicals.
Notably, there is a difference in using recycled content in a plastic and reusing the plastic.
Recycling recently has come under varying levels of scrutiny with respect to the morality of low overseas sweat-shop type wages in both the recycling facility and then the low wage, sweat-shop plastics molding facility. Certainly though the idea of recycling plastics is a good idea.
Reusing plastics, on the other hand is quite sustainable. Reusing available materials, as is a focus of the many green building programs, prevents materials from ever reaching the landfill without an additional step of shipping overseas, grinding, melting and re-molding.
Issues with reusing plastics include; consistency and quality control, The same issues exist with re-ground and re-molded plastics but on a different level - one easier to quantify in technical terms.
Kent Thompson, a Green Roof Professional here in the states commented on the Capitol GreenRoof Discussion board about a demonstration green roof using reused drainage material. Kent writes:
"Currently, I'm building a demonstration roof with upside down nursery flats filled with styrafoam packing peanuts (not the newer biodegrable variety) as the drainage layer. Both of these materials were diverted from the waste stream. I doubled up the flats for extra durability during installation. The flats have several holes drilled in each side and are imperfectly adhered to the waterproof membrane to facilitate drainage. "
I added several thoughts, including;