Greens leader Adam Bandt revealed his party would back the government's Housing Australia Future Fund legislation, in exchange for a commitment to tackle immediate rental stress and a $2.5 billion per year allocation to purchase existing properties for social housing.

The new demands are similar to the Greens' original position but come at roughly half the cost to the government.

But Housing Minister Julie Collins slammed the party, whose votes are needed to get the proposal through the senate, for seeking to delay much-needed housing.

"Australia desperately needs the 30,000 new social and affordable rental homes the fund will deliver in its first five years," she said.

"What we don't need are proposals that won't work, are not backed by evidence and would only make our housing challenges worse."

Greens housing spokesman Max Chandler-Mather said millions of Australians were falling into rental stress and rent freezes in other countries had helped to reduce rents.

"This is one of the worst housing crisis in this country's history and if (the government) can find $30b a year for the stage three tax cuts ... why can't they find $2.5b dollars for public and affordable housing and $1b for a freeze on rent increases," he told ABC Insiders.

Mr Chandler-Mather said government's proposed $10b future fund gambled on the stock market, with no guarantee of producing any money to invest in affordable housing.

He said he would not be able to look people in his electorate in the eye if he voted for a plan that would make the housing crisis worse.

"The shortage right now is 640,000 social and affordable homes and that is going to increase by 75,000 homes (but) the government has said they can build up to 30,000 homes over the next five years," he said.

"That is not a response to the housing crisis."

New demands for passing the bill include that government offers states and territories an additional incentive of $1b a year in return for imposing a two-year freeze on rent increases, ongoing rent caps and improved renters' rights.

Previously the party was demanding a $1.6b incentive fund for states and territories to ease rental stress.

Secondly, to pass the legislation, the Greens are asking the government to commit $2.5b every year to purchase expiring social housing, off-the-plan homes or otherwise vacant unused properties to add to existing stock.

The sum is half of what the Greens had originally proposed.

Mr Chandler-Mather said his party was willing to negotiate but was adamant government should not leave renters behind.

Australian Associated Press