Riefa boards are a new type of green roof substrate. They are a hi-tech fibre board made from organically grown and sustainable natural resources, including rye flour and tree bark. There are some other ingredients in there too, but forgive me if, for reasons of commercial confidence, I don’t expand on them here. But rest assured they are innovative and do what the designer intends. http://www.riefagreenroof.co.uk
A Sedum roof is not only aesthetically pleasing all year round, but also provides a habitat for a rich variety of wildlife. A sedum roof significantly reduces rainwater runoff whilst lowering energy consumption.