This compares to Toronto in Canada which has about 500 green roofs and Germany's Munich,which has 300 hectares of green roofs.
In 2009,Toronto was the first city in North America to adopt a bylaw to require and govern the construction of green roofs.
Former Melbourne Lord Mayor Robert Doyle said in 2015 he did not support mandatory building rules to ensure that roof space was used to help green and cool the city.
City of Melbourne planning chair councillor Nicholas Reece said the 1 Treasury Place green roof was a great example of the council and state government working together to tackle climate change.
Cr Reece said the council also offered seed funding to encourage developers to install green roofs but had not introduced mandatory policies such as those in Toronto,Munich,Denver,San Francisco and – most recently – New York City.
"I think we need to keep a close watch on how current interventions are going,"he said.
"If they are not delivering to the same degree as other cities we like to compare ourselves to,then we need to revisit and think about further interventions."
Associate Professor Nicholas Williams from the University of Melbourne will lead a team that will research the barriers to green roof take-up in Australia,what plant species are best suited,maintenance and irrigation requirements and costs and which designs have the most wellbeing benefits.
He said the design of the rooftop was yet to be finalised but would include a range of exotic and native species,wildflowers,medium sized shrubs and grasses.
"Green roofs bring biodiversity back into cities – native animals are attracted onto roofs,"Dr Williams said.
He said there were also a range of social and economic benefits,including an improvement in productivity when people were able to look at green roofs.
The 1 Treasury Place building was constructed in the 1960s. It was designed by architect Barry Patten from Yuncken Freeman Architects,which won a competition that required entries to express “soaring wonderment”.
However Patten ignored this direction,arguing that a skyscraper"would destroy probably Melbourne’s best vista".