Donald Trump once referred to him as “the worst mayor in America”, but Bill de Blasio wears the criticism with pride.

The New York mayor frequently clashed with Trump during his two terms in office over his socially progressive policies, including an affordable housing initiative for 300,000 families.

De Blasio says that as demand for housing exceeds supply globally, aggressive policies, like those he championed in New York, are needed in cities like Melbourne.

“Affordable housing supply has just not kept up with population changes and employment changes, and also just the sheer price reality,” he says. “At this point we have both a climate crisis and an affordable housing crisis, and both of them demand more housing around transit hubs.”

De Blasio’s administration introduced higher-density zoning in New York near major subway and commuter stations, a strategy the Victorian government is pursuing under its framework of 60 activity centres around Melbourne, including in areas such as Camberwell, Brighton, Ringwood and Frankston.

De Blasio and Carlos Moreno, the pioneer behind the concept of the 15-minute city, are the headline international speakers joining local experts to discuss Melbourne’s future at a conference to be presented by The Age and the University of Melbourne in October.

Melbourne Assembly will bring together some of the world’s brightest minds in city planning, innovation, education, arts and sport to discuss ideas for the city’s future as we accelerate towards a population of 9 million people by 2050.

It will consider Melbourne’s status as a megacity and the critical tensions that rapid expansion brings, while diving into the debate about whether Melbourne should grow up or grow out.

Government has to get involved

De Blasio was mayor of New York from 2014 to 2021. He led the city through the challenges of the COVID-19 pandemic alongside focusing on affordable housing and homelessness, justice system reform and early childhood education.

He believes government intervention is essential to tackling the housing crisis.

“Every country, every city is different, but I think there’s some broad commonalities,” de Blasio says over a video call from his home in New York. “If we agree that the market has a crucial role to play, but is clearly not performing sufficiently for a group of people, and I would call those working-class people broadly, by definition, government has to get involved.”

In some places, he says, red tape must be slashed to encourage housing development, and in other areas state action is required, such as the mandatory inclusion zoning policies he introduced in New York.

The latter allow private developers to construct higher or denser buildings than would normally be allowed in exchange for a commitment that about 25 per cent of new units will be affordable housing.

“Our mandatory inclusionary zoning was a very aggressive policy because we said literally we will not give you a permit to build higher unless you agree to what we need for the public,” de Blasio says.

The City of Melbourne has advocated such zoning in the past, but Lord Mayor Nick Reece recently announced plans to abandon these targets, arguing current economic conditions would cause the policy to further constrain housing supply.

The Victorian government has drawn criticism for using a limited version of inclusionary zoning on public land, often requiring only 10 per cent affordable housing in deals with private developers.

In New York, rezoning efforts in areas such as Manhattan and Brooklyn faced legal battles and furious opposition from some residents worried huge buildings would alter the character of their neighbourhood.

“This upzoning approach of super luxury towers with a small set-aside for affordable units is bad for New York City, bad for our neighbourhoods, and bad for affordability,” Andrew Berman, executive director of the Greenwich Village Society for Historic Preservation, told The New York Times.

The Victorian government’s seizure of planning controls, enabling developers to bypass local councils to build high-density apartments of up to 20 storeys, has faced similar opposition locally, sparking protests in Brighton.

A formula for disaster

De Blasio says planners who want to shake up the system to build more housing must be mindful of history and aesthetics. But maintaining the status quo, he argues, is “a formula for disaster”.

In the United States, he points to San Francisco as a cautionary tale where an unwillingness to build taller and denser apartments facilitated massive income inequality and helped create “almost a gilded city for the wealthy”.

“We should not underestimate that a healthy city has to have housing for working people, and an environmentally healthy city has to concentrate the housing as close to transit as possible,” he says.

De Blasio also advocates greater regulation of rental increases for young people, who may never be able to afford to buy their own home.

In New York, more than 2 million people live in private apartments where the rent increases are decided annually by a public board. A freeze on these increases was central to Zohran Mamdani’s successful mayoral campaign in the city last year.

De Blasio is blunt about the impact of this public regulation.

“New York City would cease to exist as a viable economy, in my view, if we didn’t have rent regulation for about a quarter of our population,” he says. “We would not be able to house all the people who do the work.”

De Blasio says that in New York, residents pay between a third to a half of their income in rent, a similar ratio to Australia, where the typical renter spends about one-third of their household income on rent.

Office building conversions

Another solution de Blasio backs is turning office space into housing, which he says is happening on “a decent scale” in New York.

In Melbourne, converting office buildings into apartments was put on the agenda by the Property Council when it identified 86 office buildings in the CBD that were suitable for conversion.

The idea was seized upon by the state government and included in its landmark housing statement. However, owners of the city’s office buildings were not consulted and did not back the proposal.

Reece promised incentives from the City of Melbourne for office conversions in his campaign to be elected lord mayor. But retrofitting these buildings can be difficult because of the different access to light, plumbing, electricity and lift wells required for apartments.

An office building conversion in Manhattan almost collapsed last month, leading de Blasio to concede “there’s some work to be done” in the area.

“For many buildings, it’s a lot of work and expense to make the conversion. It may not be worth it,” he says. “For some buildings it works. I’m not an economist, but if someone owns an office building and the demand levels have shot downwards, they’ll look for that conversion if it’s at all feasible.”

For de Blasio it’s all part of trying to maintain the social fabric of a city by making it a place people can afford to live.

For a city to succeed, he believes it needs an energetic pool of talented people and, in an increasingly globalised world, these people will move to cities that are culturally vibrant but also accessible economically.

If these beliefs led to him being described as America’s worst mayor by Trump, then de Blasio is sanguine about the assessment.

“It’s a badge of honour,” he says.

Melbourne Assembly will be held from October 19 to October 21. More information is available on the Melbourne Assembly website, including special offers for Age subscribers.