Green roofs are good for:

1) BIODIVERSITY - provide new semi-natural habitats for different birds and invertebrates
2) AIR POLLUTION MITIGATION - roofs with shrubs and grass have the largest impact on reducing the amounts of particulate matter, ozone nitrogen dioxide and sulphur dioxide during day time and in-leaf season
3) ENERGY EFFICIENCY FOR BUILDINGS - green roofs have delivered savings of about 25% in energy bills
4) STORM WATER MANAGEMENT - effective way of storing rainwater because of the plants and growing medium absorbing capacities
5) AESTHETIC - views of a natural setting reduce stress levels and decrease heart rate
6) USE OF RECYCLED MATERIALS - recycled materials such as crushed bricks are used for membranes and drainage mats; the growing media could contain also compost from recycled households, agricultural and horticultural waste
7) PROPERTY VALUES - proper design and planning since the early stages of a new building or in an existing building (retro-fitting) will be beneficial to the overall property value

See master thesis from CEU. See more pictures from Faroese green roofs