Create green open spaces
Increasing urban density decreases ground level green space. Roof gardens negate, to some extent, high density development.

Retain and manage rainwater
Green roofs absorb up to 75% of rainfall, thus reducing the runoff dramatically, and lowering the risk of floods.

Provide diverse habitats
Roof gardens, when planted with indigenous flora, can provide important habitats for native bird and insect populations.

Modify urban micro-climates
Cities, of concrete and tarmac, retain heat and create "urban heat islands", as much as 5C warmer than surrounding suburbs. Plants, through transpiration, directly cool the air, and can reduce surface roof temperatures by as much as 40C in summer.

Improve air quality
Plants produce oxygen, and remove carbon dioxide from the air. They also trap up to 85% of airborne particulates on their leaf surfaces.

Insulate against heat and sound
Buildings with roof gardens lose 30% less heat in the winter, are cooler in the summer, and offer year-round sound insulation.

Provide economic benefits
Roof gardens and green roofs extend the life of the existing roof fabric by up to 70%. Further savings are also made from improved insulation. They also substantially enhance re-sale values.

Provide social benefits
Planting gardens, both at ground level and in the sky, alters both the sensible and psychological climate for the better.