Some parts of Sydney continue to suffer through drastically worse heat than others, with Penrith sweltering through 37 days above 35 degrees Celsius last summer compared to just six hot days in both the CBD and Terrey Hills.
Parramatta had 19 hot days and Bankstown had 20 hot days in the same period, according to a new report released by the Greater Sydney Commission that brings together data from across government to track the evolution towards a metropolis of three cities.
The report (also an online dashboard) found that much of Sydney is experiencing high exposure to urban heat. Although the western city district is hit with the worse impacts of heat (46 per cent of residents exposed to high urban heat in 2016), the central, south and eastern city districts are also affected by high urban heat.
At the same time, these four districts also have low tree canopy cover. Good canopy can lower land surface temperature by 1.13 degrees Celsius.
The only part of Sydney with high canopy cover is the north, with 40 per cent canopy cover and just 2 per cent of residents exposed to high urban heat. The remaining districts are much lower, with the total tree canopy cover of the urban area in greater Sydney just 21 per cent in 2016.
The eastern city district actually has the lowest urban tree canopy cover at just 15 per cent, followed by the western city district at 16 per cent and the central city district at 17 per cent.
Mapping of the urban heat effect – where buildings, roads and other hard and dark surfaces absorb and store heat – shows it is highest in the western city district and lowest in the northern district.
According to GSC, the plan is to keep increasing tree canopy in the urban area to improve amenity and address urban heat, which is only expected to increase in the future as a result of climate change and increased urbanisation.
Other cooling methods include protecting and integrating waterways near neighbourhoods and increasing access to cooler places and support networks for communities experiencing urban heat.
- See our story Mat Santamouris: time to make buildings heat-safe. Now.
Not only are extreme temperatures unpleasant and can cause heat related deaths and illnesses, it also cause more people to spend time indoors such as in cinemas and shopping centres where there’s energy-guzzling airconditioning, Helen Liossis, head of corporate strategy and business planning at Sydney Water, told The Fifth Estate last year.
Ms Liossis said that although greenery does have a cooling effect in the hot parts of Sydney, her research found the most effective urban heat mitigation technologies use a combination of water based technologies (including fountains) in conjunction with cool material technologies, such as cool roofs and pavements.
Water misting systems can also be effective, she says, and don’t use much water.
How Sydney is tracking on its other liveability metrics
The Pulse of Greater Sydney measures progress on implementation of the Greater Sydney Region Plan and the five District Plans through four key indicators: Access to jobs, education and housing, 30-minute cities, walkable places, and addressing urban heat.
The aim of the 30-minute city is for residents to be able to reach their nearest metropolitan centre/cluster or strategic centre using public transport or walking within half an hour.
A couple of different tools have been used to measure this, but in each instance the eastern city district has the highest percentage of dwellings located within 30 minutes of a metropolitan centre or cluster.
The eastern district also has the best walkability, with 32 per cent of trips walked in 2017-18, and the western district the worst.
The report found a miserable 1 per cent of people are cycling to work in Sydney, with another 5 per cent walking. The private car accounts for more than half of all commutes, with public transport around a third.
The western city district is the most dependant on cars to get to work and the eastern city district the least. Around half of commuters in the east are catching public transport to get to work.
The report also found that jobs growth has been uneven across the regions. Although 78 per cent of residents of the eastern city district live and work within their district, this is true for only 60 per cent in the north district, 57 per cent in the western city district, 52 per cent in the central city district and only 43 per cent in the south district.
“An increase in jobs, particularly knowledge jobs, and tertiary education opportunities in the western city and central city districts is needed to address the current imbalance, particularly as the population of these districts is growing at a faster rate than other districts.,” the report states.
“Growing centres in these districts will assist in creating knowledge jobs which are largely concentrated in metropolitan and strategic centres, economic corridors and health and education precincts.”
When it comes to housing, the eastern city district has more apartments (49 per cent) and smaller households whereas the western city district has more separate houses (80 per cent) and larger households.
But this gap is narrowing, according to the report.
The proportion of apartments jumped across all districts in the decade to 2016 compared to the increase of separate houses and medium density, with the largest increase was in the central city district where the number of apartments grew by 75 per cent.
On education, over the 10 years to 2016, the number of students attending university across greater Sydney increased by 64 per cent.
The Pulse of Great Sydney has great datasets. However, you get what you measure. 30 minute city sounds as if it is all about workers, but there are many more citizens that travel for other reasons – older people in particular. And liveability has to be about everyone, not just people of working age and able to work. I wonder if some marginalised groups got left out of the datasets? Or worse, considered as a “social problem” to be fixed by separate policies. That’s not an inclusive liveable city.
The causes of the urban hot island effect have been know for decades. Increased hard cover tar cement, less trees and higher densities all the features done and continuing to be done by the GSC.