The ACT Greens will take to the ACT election a policy of spending $5.9 billion to build and buy 10,000 new public housing dwellings over the next decade.
The party, which paid for the proposal to be independently costed, said the policy would "fundamentally reshape Canberra's housing market".
Deputy Greens leader Rebecca Vassarotti said the only way for the ACT government to fix public housing was for it to step in.
"This is the biggest housing affordability initiative ever proposed in the history of self-government," Ms Vassarotti said.
"This $2.2 billion investment over the next term of parliament will be through direct funding from the government.
"The Greens will also fight for co-investment from the federal Labor government to make up for the decades of neglect that has caused the crisis in public housing."
The policy includes establishing a government-owned housing developer, establishing a hub to manufacture prefabricated public housing and establishing a government-owned public housing maintenance provider.
The Greens' policy also includes establishing a pilot program to allow Canberra homeowners to sell their properties to the government to increase public housing stock.
An assessment of the policy by Purdon, an ACT consulting firm, found the government's deficit would increase by $1.7 billion over a decade.
"The modelling suggests over 10 years the policy will require capital injections of $5.9 billion to Housing ACT, appropriations to support the capital injections of $10.1 million, and public debt interest of $1.7 billion. Revenue from land sales will be $137 million lower, and Housing ACT may have a higher accumulated operating deficit," the Purdon report, released by the Greens, said.
The Purdon assessment assumed around 2295 dwellings would be purchased in the open market, a further 2000 would be built in greenfield areas, and the remaining 5355 will be built on infill sites.
"The program will put the ACT on track to return the ratio of public housing towards 10 per cent, last seen in the 1990s, and improve the quality of life for the thousands of Canberrans who struggle with no housing or unaffordable rentals," the assessment said.
Greens leader Shane Rattenbury said the government needed to prioritise people over profit in a transformed housing market.
"When Canberra was first established the government did build homes, and most people lived in public housing," Mr Rattenbury said.
"Canberra needs many more publicly owned, affordable and high-quality homes. Together we can change public housing from being seen as a last resort, to being a landlord of choice and an affordable housing option for all Canberrans."
The ACT Greens have been part of a governing coalition in the Legislative Assembly with ACT Labor since 2012.
The party's proposal for a publicly owned property developer echoes the federal Greens' $28 billion policy for a Commonwealth-owned developer, announced last month.
Sam Nugent, a Greens candidate for Brindabella, said: "After going through an expensive divorce, a few years ago I found myself working homeless.
"Despite being on a relatively high income, I was forced to sleep in my car or under my desk. Unfortunately, this is a harsh reality facing more and more Canberrans. And it needs to stop.
"Every Canberran deserves the security and dignity of having a roof over their head. And the Greens want to make that happen."
The number of public housing properties in the ACT fell to its lowest level in a decade, Productivity Commission data released in January showed.
The ACT has 10,744 public housing properties. The number of properties peaked in 2018 when the territory had 11,181 dwellings, with a downward trend since.
ACT Housing Minister Yvette Berry in 2023 said public housing stock in the territory is unlikely to have a notable increase for another two years.
"A whole range of things have to match up together to get new houses built and to get people into homes. You have to move people from homes, we have to demolish those homes, we have to sell those homes and we have to build new homes," Ms Berry said in November.
"All that doesn't happen in a nice straight line it is a bumpy line."
The ACT has collected $1.1 billion from the sale of public housing properties since 2011-12, an answer to a question on notice revealed.
In the same period, the government has spent just over $990 million on new properties, including the purchase of land, construction costs and selling expenses.
The government's current public housing program aims to renew 1000 and add 400 new properties to its stock in the capital.
More to come.
