Evaporative cooling from water capture and holding. Noise control (hard surfaces such as concrete and glass provide much stronger reflections and therefore nosier environments) Less smog and better air quality etc.
See our other green wall and green roofs websites:
Less sewer overflow due to rain harvesting. Longer life of pipes and storm water systems as less water which is better filtered runs off the roof area. Biodiversity in plantings leads to increased biodiversity in insects and birds which would not otherwise live in an urban environment etc.
Thermal mass provides a cooler building and energy savings. Roof longevity. Better environmental building rating (e.g. Green Star rating ) etc.