Shrinking backyards could be making your suburb hotter

Flanked by two looming townhouses, Jyoti Dhakal’s suburban bungalow might look out of place. 

The engineering consultant moved to Clayton in south-east Melbourne in 2013, with her husband and two young children.

Back then, she said the neighbourhood felt like a typical Melbourne suburb, dominated by family homes and single-storey units.

But things have quickly changed.

A black and white photo of a woman crossing a road in 1969 with some vehicles lined up.
Clayton looked very different back in 1969. (Flickr: Monash Public Library)
A view of traffic at a busy intersection.
Today Clayton’s streets are busier and more developed. (ABC News: Prianka Srinivasan)

“Ever since we moved here, the prices have gone up,” Ms Dhakal said, adding increased demand has led to older houses being demolished to make way for new townhouses.

Clayton is set to become a “mini-CBD” to cope with a booming population, and rapid development is underway to cater to these new residents. 

A few trees are planted near the railway line in Clayton, with car traffic at an intersection.
Clayton’s new skyrail has eased traffic congestion, but some residents are concerned about the lack of greenery surrounding new developments. (ABC News: Jarrod Fankhauser)

Monash City Council has rezoned residential areas to “facilitate apartment-style development”, particularly targeting students from the nearby Monash University campus.

There are currently no controls in Clayton to regulate the removal of trees on private land, and some residents are noticing gardens being eaten up by this demand for higher-density housing.

An old one floor house next to a three-storey structure.
New townhouses are built alongside existing single-storey dwellings in Clayton, south-east Melbourne. (ABC News: Hellena Souisa)

“You see more of concrete buildings, [so] obviously there is … bound to be less vegetation,” Ms Dhakal said.

“It is a bummer.”

Council policies aim to protect vegetation and ensure developers maintain green spaces, but in the area surrounding a new train station and skyrail, Ms Dhakal has noticed a particular difference.

“It is hotter because you have that concrete built over there,” she said. 

A woman looks at a building facade jutting out.
A new development towers over Ms Dhakal’s home. (ABC News: Prianka Srinivasan)

Temperatures rise as plot sizes shrink
It’s a familiar sight across many Australian suburbs.

Demand for housing has led to a rise in subdivisions, and a loss of yard space and the trees they contain.

A black and white image of a cottage with long grass or shrubs surrounding it.
This cottage, pictured in 1970 in Clayton South, has now been replaced. (State Library of Victoria: JT Collins Collection, La Trobe Picture Collection)
An exterior view of two houses close to each other with a 'For Lease' sign and wheelie bins out the front.
Multiple townhouse units are now on the same block. (ABC News: Prianka Srinivasan)

Block sizes for new houses across Australian cities have plummeted by 22 per cent – to an average of 467 square metres – in the past 15 years, according to the Australian Bureau of Statistics.

In Melbourne alone, about 240,000 new lots – including houses and units – have been created since 2015 as a result of subdivision. 

And while the size of land is shrinking, house sizes have remained the same, according to the ABS – meaning more Australians are building big houses with smaller yards.

That combination is leading to a dramatic loss of residential trees and vegetation.

Gregory Moore, a senior research associate at the University of Melbourne, has been studying Australia’s declining urban canopies.

“In most Australian cities, the density of the canopy cover is diminishing at various rates,” Dr Moore said.

A photo of a man standing in the gap of a truck of a tree.
Dr Moore says the loss of greenery on private property is contributing to heat islands. (ABC News: Hellena Souisa)

“Nearly all of the change is happening on privately owned land … and most of it is the redevelopment of large blocks into smaller blocks or into townhouse developments.”

The trend is exacerbating an urban heat island effect, where hard surfaces like concrete and steel absorb and then release heat.

Trees and the shade they provide can help reduce the impact, but stripping away that canopy accelerates the effect.

It can make our cities 4-10°C hotter than surrounding rural areas, according to research from RMIT’s Sustainability and Urban planning program.

Two people in warm clothing sit on a street bench under a large tree.
Experts say tree cover can help cool Australian cities. (ABC News: Jarrod Fankhauser)

Associate Professor Joe Hurley and his RMIT colleagues have mapped vegetation loss in a number of Australian cities.

They found several outer suburbs in Melbourne and Sydney were most vulnerable to the heat island effect.

“Areas like the western suburbs of Sydney and the western suburbs of Melbourne, where we see lower socio-demographic factors, we also see lower vegetation and higher susceptibility to heat,” Dr Hurley said.

A side-by-side of suburbs in shades of green reflecting the amount of tree coverage.
Maps from the Clean Air and Urban Landscapes Hub show the low percentage of tree coverage in Clayton, Melbourne and Stanhope Gardens, Sydney. (Supplied)

Melbourne’s south-east, where Clayton is located, might look leafy and green from above, but Dr Hurley’s team found vegetation cover between 2014 and 2018 decreased by about 1 per cent.

That equates to 131 hectares, or more than 60 MCG stadiums.

Other nearby areas have been more affected, with outer eastern suburbs of Melbourne losing more than 2 per cent of their tree canopies in the same period.

Dr Joe Hurley 1
Dr Hurley and his team at RMIT have developed a heat vulnerability index. (ABC News: Hellena Souisa)

A tree canopy cover of around 20 per cent is ideal, Dr Hurley said, but Clayton and its surrounding suburbs currently have a vegetation cover of around half that.

Dr Hurley said the loss of this tree canopy was leading to higher temperatures, and could have dire consequences.

“Cities like Melbourne, Sydney, Brisbane have considerable deaths that have been attributed to heat waves in our cities, exacerbated by the urban heat island effect,” he said.

Families ration aircon to cope with heat

A older Indian man and woman. He has his hands on her shoulders.
Anoop Sud and his wife Neera are finding ways to keep cool but keep power costs low. (ABC News: Mridula Amin)

It’s not just Melburnians feeling the burn.

In Western Sydney, demand for housing and the rise of subdivisions have similarly shrunk urban forests, and made communities less heat tolerant.

Temperatures here can get up to 10°C hotter than suburbs closer to the coast.

Anoop Sud lives in Stanhope Gardens in Western Sydney, and has seen it rapidly develop over the past 11 years.

Having migrated to Australia from India, Mr Sud said he was used to overpopulated cities, but now felt “claustrophobic” because of the number of houses and people.

As his neighbourhood becomes more crowded, he is finding it harder to escape the extreme heat – in February last year, temperatures soared to 44.5°C, and Mr Sud found it difficult to breathe.

Just a month prior, in the heart of the 2020 bushfires, nearby Penrith in Western Sydney was deemed the hottest place on earth, reaching a high of 48.9°C.

A man with grey hair sits across a chess board from a young girl, with a fan in the background.
Anoop Sud and his family are struggling to deal with hot summers. (ABC News: Mridula Amin)

Despite installing solar panels to offset energy costs, Mr Sud still finds it too expensive to cool his entire house during summer.

“We, as a family, move into one section of the house, stay together, and put on the AC there,” he said.

“Otherwise, if you start cooling the entire house, the cost will go up.”

A family sitting around a dinner table.
The family of nine gather together to avoid aircon costs. (ABC News: Mridula Amin)

Shade provided by trees alone can reduce ambient temperatures by an estimated 8°C, leading to a reduction in air conditioning costs and electricity savings of 12-15 per cent per year, a study from Dr Moore found. 

Thuy Linh Nguyen from Voices of Power, a campaign that advocates for more affordable and cleaner energy, said the people of Western Sydney were suffering the burden of the urban heat island effect.

“It’s really hard to keep it cool or warm, and so people are spending a lot of money to keep their houses cool in summer,” she said.

“We’re hearing about people taking their mattress out and onto the lawn to sleep there.”

A photo of a young woman of Vietnamese heritage smiling.
Ms Nguyen says some homes are harder to keep cool. (Supplied)

Ms Nguyen said many people vulnerable to heat waves lived in “leaky homes” – or inefficient homes with poor insulation – that used a lot of energy to keep cool, and it could be expensive to make homes more efficient.

She is urging governments to give households “support through grants to be able to upgrade their homes, so they can cool their homes really well”. 

Thermal inequity

A leafy shady street on top in Toorak and a sunny street with fewer trees in Clayton.
Some suburbs have more well-established trees than others. (ABC News: Prianka Srinivasan)

Not all suburbs are losing trees at the same rate.

In some of Melbourne’s wealthy inner-city suburbs, dense trees wrap around streets providing sun protection even on a sizzling summer’s day.

Dr Moore and other researchers found that houses on a tree-lined street can be up to $30,000 more expensive than those that have very sparse vegetation.

“The green and leafy suburbs were definitely suburbs that were not intended for the working class,” he said.

“So there are social, historic and ecological reasons why there are differences in vegetation cover.”

For example, 60 years ago, much of Clayton was cleared and flattened for farmland and factories, which is why it can be difficult to find tall, well-established trees in the area.

A view of Clayton from above with houses and trees.
Clayton may look leafy from above, but its tree canopy coverage is lower than many other suburbs. (ABC News: Jarrod Fankhauser)

Melbourne’s northern suburbs were always dry and arid, even before European colonisation, and that geography means its residents are particularly vulnerable to rising temperatures today.

“The way we are developing new suburbs on the fringe continues to be in a mode that delivers very little private vegetation, very little space for private canopy trees,” Dr Hurley from RMIT said.

“This is not helping to cool these suburbs.”

Heat-proofing our future

A photo of an older couple smiling and laughing with greenery around them.
Lyn and Michael Lawson are beating the heat with their green thumbs. (ABC News: Prianka Srinivasan)

Hidden behind a dense cover of leaves and trunks stands Lyn and Michael Lawson’s weatherboard home.

Like many of their neighbours, the couple have noticed rapid changes on their streets. They complained to council about the three-storey townhouses being built over the fence that look directly into their yard, to no avail.

“There’s a lot more cement than there used to be, and people are growing less trees,” Ms Lawson said.

“We find it distressing because it’s just blocked buildings and you can’t see beyond them … we just find it very invasive.”

The Lawsons have lived in Clayton for the past 30 years, slowly developing their flat and uninspiring garden and backyard into a suburban oasis.

An old photo showing a white house with a brown tile roof and construction.
The Lawsons have transformed their home, pictured here in 1991. (Supplied: Lyn and Michael Lawson)
A house shrouded in green plants.
Thirty years later, their home is rich with greenery. (ABC News: Prianka Srinivasan)

During summers, the couple have been able to keep cool by finding shade under their thick canopy of vines and trees.

“We love trees. We love fruit. So most of our yard is fruit trees,” Ms Lawson said.

Protecting these trees on private properties is one way to avoid the worst of the urban heat island effect, experts say.

But the decision should not be left up to garden-loving families like the Lawsons.

An older couple stand in their backyard with blue sky above and new apartments behind them.
The Lawsons are unhappy with the townhouse developments overlooking their yard. (ABC News: Prianka Srinivasan)

“We need to be balancing that provision of new housing, that new development, with the provision of urban trees and vegetation to ensure that we have an extensive and functioning urban canopy and urban forest to help keep cooling those neighbourhoods,” Dr Hurley said.

Councils are adopting laws to make it harder to remove residential trees and encourage property developers to make space for gardens.

Monash City Council, for example, has put in place a Tree Management policy and Street Tree strategy to better preserve vegetation, and plants approximately 1500 street trees per year. 

The letters CLA overlook concrete ground as a train moves on a railyway track overhead.
Clayton is becoming a “mini-CBD” to cope with a swelling population. (ABC News: Jarrod Fankhauser)

State governments are also taking note. Proposed planning laws in Canberra would require new developments to have a minimum 20 per cent tree cover. 

In Victoria, the government aims to plant 500,000 trees across Melbourne’s western suburbs, an area that experiences the highest urban heat island effect.

It will also introduce new planning guidelines this month, proposing a 30 per cent tree canopy target for Melbourne’s new growth areas.

A view of light and shade and urban playground equipment under an above-ground railway in Clayton.
Some residents are concerned new development is creating heat islands. (ABC News: Jarrod Fankhauser)

But with suburban populations set to rise as climate change makes our summers even hotter, some experts are urging Australians to rethink their love for large homes on suburban subdivisions.

Dr Moore from the University of Melbourne said that more developed land should be set aside for plants.

“That doesn’t mean that you wouldn’t have dense housing. But it does mean you would have to go up,” he said.

© 2020 Australian Broadcasting Corporation. All rights reserved.
ABC Content Disclaimer

Written by ABC News



SPONSORED LINKS

LOADING MORE ARTICLE...