InDaily can reveal the plan is based on a scheme running in Melbourne, under which the Victorian Government agreed to let a not-for-profit build portable, single-bedroom houses on its vacant land.

The movable houses – about 60 of them – would be funded by a one per cent tax on unoccupied properties across South Australia.

Costings from the Parliamentary Budget Office (PBO) requested by the Greens, estimate the tax would bring in about $5.7 million to fund the houses.

Greens candidate for Adelaide Robert Simms told InDaily it was a “travesty” that there were “thousands” of properties left unoccupied in South Australia while hundreds of people were sleeping on Adelaide’s streets every night.

“We’ve got a big problem here in South Australia when we have got thousands of properties sitting there vacant … yet we have got hundreds of people in Adelaide who are (sleeping rough),” he said.

“It’s a travesty … housing is a fundamental human right.”

Simms argued that the property tax – which would only apply to private property left unoccupied for more than 12 months – would encourage higher rental supply and increased property sales, therefore placing downward pressure on property prices.

“We are allowing people to stockpile property at the expense of others that are trying to get into the market,” he said.

“These people need to be encouraged to activate their homes.”

He said the portable houses – costing about $80,000 each – would be placed in groups, to facilitate the best access to services, and could be accommodated voluntarily on public or private land.

But the plan is light on detail.

Simms said he did not know which vacant properties in Adelaide’s CBD could be used for the purpose of accommodating the transportable houses – though he said there were “heaps” of them, including government properties and empty parking lots.

“We’d need to find appropriate sites,” he said.

“It could well be on vacant government land.

“I haven’t … done work in terms of identifying sites.”

Asked how the transportable houses would gain access to electricity, water and sewerage, Simms said some could be equipped with self-contained amenities – though he said they would certainly have to be connected to a water supply.

He could not say what would happen if a property owner decided they no longer wanted the houses on their land, but stressed that the houses could be moved quickly if required.

“These are the kind of questions that would have to be worked out … in consultation with agencies,” he said.

Simms invited other political parties to take up the policy.

InDaily contacted Liberal MP Rachel Sanderson and Labor candidate for Adelaide Jo Chapley for comment.

Simms attracted 11.8 per cent of the vote when he contested the seat of Adelaide in 2014.

Sanderson holds the seat on a 4.8 per cent margin.