On Monday, Greens' Caroline Le Couteur said since opening in 2015, the Common Ground site had provided "significant support to those in need" but needed to be expanded.

Ms Le Couteur said the demand for crisis and affordable housing was growing in Canberra and an additional building at the Common Ground site was needed to accommodate the demand.

"As the Government already owns the surrounding vacant land on site, it would be simple and cost-effective to duplicate the current building, expanding housing opportunities to help both Canberrans experiencing homelessness and those in need of affordable housing," Ms Le Couteur said.

The $17-million Common Ground project was an initiative negotiated as part of the ACT parliament's Labor-Greens agreement and unveiled to combat homelessness in Canberra.

It is made up of 40-units, half of which are for tenants who have experienced long-term homelessness, and the others offered as affordable rental accommodation.

"The 40-unit complex is right next to the Gungahlin Town Centre, the light rail will soon be open," she said.

"There are lots of shops, lots of facilities, it has a lot of services which makes it a particularly good place for homeless and low-income peopleAmazin to live."

An initiative that started in New York, Ms Le Couteur said Common Ground was an effective model of responding to homelessness and has since been successful in many other cities.

Community services executive director Kate Cvetanovski said there was now denying the project was helping to end homelessness.

"You can end homelessness by having a house, having 20 or 40 additional units or housing to end homelessness is life-changing for the people that receive it and would go a long way ending homeless in Canberra, especially street homelessness where we've expeditionary grown over the last three years," Ms Cvetanovski said.