The average annual rainfall in the Wellington region is 1270mm – with 850mm falling in the city centre. With an estimated 1,000,000 square metres of rooftop surface in the C.B.D 850,000,000 litres of water is siphoned away from the city contributing at times to wastewater overflow problems at the Moa Point Wastewater Treatment plant. Wellington rainfall is expected to increase with changes to the global climate along with population growth placing extra pressure on already inadequate stormwater and wastewater infrastructure.
Various studies have shown that a green rooftop will absorb on average 75% of rainfall through plants which later release the water through there leaves by osmosis.
From the multitude of vantage points around Wellington it is plain to see the amount of underutilised spaces on top of buildings. Each has the potential to become a living roof, soaking up rain, growing plants, supporting insects, butterflies and birds. Green roofs for plants, brown roofs for insects and roof gardens for people.