With no end in sight to Australia's homelessness crisis, one charity is taking an innovative approach to housing people in need — a pop-up shelter.

Uniting Care has repurposed one of its out-of-use aged care homes that is awaiting demolition into a temporary home for women aged 45 and over, who are making up a growing proportion of the homeless population.

Uniting's director of property and housing, Simon Furness, said the inner-Sydney building would otherwise be lying vacant while awaiting demolition, planned for early next year.

"We've all seen pop-ups all over the place — pop-up bars, pop-up restaurants and clothes outlets and shoe outlets," he said.

"Those are pop-ups for a commercial purpose, why not have pop-ups for a social purpose?"

A newly prepared room inside the pop-up shelter. ( ABC News: Maisie Cohen )

'Really, anybody can do this'

Mr Furness said it did not take too much work to make 30 rooms in the building fit for use. They just needed a good clean and for the utilities to remain connected.

They were furnished using second-hand items from a major hotel chain that was having a cleanout.

"We knew the building was going to be here for probably a year to two years while we do all the development applications and the planning controls and engage contractors, so it occurred to us that it's an empty building and a lot of people need homes, so we decided to reopen the building as temporary housing for older women," he said.

He urged others with empty buildings to consider whether they could do the same with their properties, which he said were often vacant for months or years during the development application and planning control period before redevelopment.

"Really, anybody can do this," he said.

"I would strongly encourage any property developer or owner-operator like ourselves to look at their building portfolio and their development plans and if there are buildings that are going to be empty, think about what they can be used for."

Former general manager for property group Frasers Property Australia, Robert Pradolin, said he believed there were thousands of empty buildings around Australia that could be used for temporary housing with the support of not-for-profit housing providers.

"Well over a decade ago, we used to throw away good food," he said.

"Then we changed the laws because it did not make … sense to discard such a valuable resource. Existing buildings sitting there empty while people are homeless on our streets does not make sense.

"We need to change the laws to allow society to help people with the fundamental human need of shelter."

Simon Furness said it didn't take much to convert the building into a shelter. ( ABC News: Maisie Cohen )

Liz Yeo, chief executive of the Newtown Neighbourhood Centre, a social services organisation in inner-Sydney, said the housing options for women like Anne were often unsafe, male-dominated boarding houses.

She said the homelessness crisis was worsening and needed innovative solutions to solve.

"We know we're not going to suddenly, magically have government be able to produce the hundreds of thousands of new homes that are needed," she said.

"So, we need organisations like Uniting and other housing providers to take these exciting initiatives and provide appropriate housing for people."

'You never think you're going to lose your job'

Anne (not her real name) is one of the 30 women who have lived in the pop-up shelter while seeking permanent housing.

The 54-year-old lost her home in March after suddenly becoming unemployed, and has since been living in her car and in temporary accommodation.

"I'd lost my job after 18 years of work, and I wasn't able to pay my rent because I live on my own," she told AM.

Anne was concerned that if she stayed in the property and was unable to pay rent, she would lose her good tenancy record.

"You never think you're going to lose your job," she said.

"I didn't have any extra in the bank [as] savings. I was on a minimum wage, so I gave the key, gave them notice, and I went to stay with a friend."

Anne said she felt lucky to have a roof over her head. ( ABC News: Maisie Cohen )

Anne said the women who were living in the pop-up shelter were finding support among each other, lending one another blankets and sharing meals.

She said even though she feared for the future, she felt lucky to have a roof over her head, because there were so many people without one.

"If there is other buildings that are going to go under demolition and they can opt to help people for three to six months, a year [they, should]," she said.

"This is a good place, and we all feel safe — it's a safe haven for us."