It shows, for instance, residents in Sydney's western district are 23 times more exposed to high urban heat than people in the city's north. While Sydneysiders in the CBD experienced six hot days over 35 degrees during the 2018-19 summer, people in Penrith sweltered through over a month's worth. "The plan is very conscious of [Sydney] as a mosaic of places – every city district is different, it has different strengths, but also there are things that we’re trying to improve in each part," Greater Sydney Commission chief executive Dr Sarah Hill said. "This is a baseline – it is our first step in really measuring the performance of our plan and vision for Sydney." The '30-minute' city The commission eventually wants all Sydneysiders to be able to reach a metropolitan centre within half an hour by public transport.

These centres are the CBD, greater Parramatta, the western city metropolitan cluster (Liverpool, Greater Penrith and Campbelltown-Macarthur) and the planned Badgerys Creek aerotropolis. But 30-minute access to these hubs of knowledge, goods and services varies greatly across the city. While almost all people from the eastern city can be at a centre within half an hour by public transport, just 24 per cent of the south and 42 per cent of the north have this capacity. However, this doesn't account for employment hubs such as Macquarie Park or Sydney airport, which are key attractions for people in the north and south.

Access to one of Sydney's 34 strategic centres is more evenly spread. In most parts of Sydney, more than 95 per cent of people can reach a strategic hub in 30 minutes. Loading But not in the west: current infrastructure and services do not allow for 16 per cent of western Sydney to access either type of urban centre with public transport within 30 minutes. "That’s something we’re working hard to address," Dr Hill said. "It’s a really critical component of the Western Sydney airport, building Liverpool, Campbelltown and Penrith to be really strong job centres, but also many of the infrastructure commitments [such as the outer west metro] to address access to jobs in the western city as it grows." Who's feeling the heat?

Bureau of Meteorology data shows temperatures last summer surpassed 35 degrees on 19 days in Parramatta, 20 days in Bankstown and 37 days in Penrith. The northern and eastern districts posted the fewest hot days, with just six over 35 degrees. "We know as you get further from the coast the weather becomes less maritime and more continental," chief commissioner Lucy Turnbull said. "But we need to make sure through better urban design [we] can mitigate heat." One way to keep cities cool as temperatures rise is to increase tree canopy cover: a 10 per cent increase in canopy cover has been shown to lower land surface temperature by 1.13 degrees.

The parts of Sydney with the most tree canopy cover are also the coolest. Ku-ring-gai, Hornsby, the Northern Beaches, Lane Cove and Willoughby have the greatest cover in Sydney. All are in Sydney's northern district, where just 2 per cent of residents are exposed to high urban heat. Exposure across the rest of Sydney is much higher: 22 per cent of people in the eastern city, 25 per cent in the central city and 46 per cent in the west are affected by high urban heat. "By understanding how [urban heat] works we can plan better ways to address it such as the premier’s priority for trees, as well as the work we’re doing around the South Creek corridor," Dr Hill said. "Also designing our houses to take better account of water, to allow for more space for trees to be grown, for solar heating on roofs, right down to different colours of buildings to ensure that they absorb less heat."

Loading Walkability and open space Along with tree canopy, the report has measured how often Sydneysiders walk and their proximity to open public spaces - all factors a citizen's panel identified as important contributors to liveability. "When you’re looking at walking as a percentage of transport it’s also an indicator of health, because the more you walk the healthier you are," Ms Turnbull said. Walking trips are highest in the east and lowest in the west, with those two districts also having the largest difference in proximity to public open spaces.