Green roofs, also known as living or eco roofs, are roofs with plants or vegetation growing on them. They're becoming increasingly popular in new builds and renovations in New Zealand. Green roofs benefit the environment by helping improve air quality, providing insulation, supporting biodiversity and reducing pollution entering waterways.
The Greenroofs website has a range of information on green roof projects in New Zealand, and how to go about your own green roof project. Also, this article from Build Magazine discusses some of the issues and cost benefits of green roofs.
Green roofs help to insulate buildings, reduce the rate of rainwater runoff and provide noise reduction benefits as well as looking beautiful. However, there are some down sides. This article from the level.org.nz website has more.