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Urban Heat

Western Sydney Cool Roads Trial

Why cool our roads?

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Roads have been identified as a major heat source in urban areas. Approximately 10% of the City of Parramatta Local Government Area (LGA) is a road or asphalt surface. This means that each and every resident and business is surrounded by roads, and is impacted by the temperature conditions being created by them.

Roads and asphalt areas absorb heat during the day, making streets and surrounding areas hot. At night, they release this absorbed heat which increases overnight temperatures.

These increased night-time temperatures make it difficult for people to rest or recover, and have been found to be of particular concern for members of the community with health conditions, the very young and older people. Increased night time temperatures also increase energy costs through the extended use of air conditioning overnight.

Combatting increasing heat in our community has been identified as a key priority in City’s Environmental Sustainability Strategy 2017


Two images: 1. street with houses and grass, 2. thermo image of street

How do you cool a road?

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Between March 2020 and September 2021, the Western Sydney Cool Roads Trial researched how effectively we could reduce the amount of heat being absorbed by asphalt roads across three Councils (Blacktown, Campbelltown and Parramatta), including three locations within the City of Parramatta.

As part of this trial, the road’s asphalt colour is lightened from black to light grey by applying two coats of GuardTop CoolSeal.

CoolSeal is a water-based sealant that is designed to reflect the sun’s rays and minimise the build-up of heat.

Council workers installing cool seal on road

Image: CoolSeal installation, Northmead - George Gittany Photography, 18 March 2020

Where did the trial happen?

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CoolSeal was installed and remains at the following City of Parramatta Council locations:

  • Corry Court, North Parramatta
  • Roslyn Avenue, Northmead
  • Binalong Park car park, Old Toongabbie.

What did the trial find?

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The key findings from the trial relate to temperature effects and community feedback:

Temperature effects

  • Tree shade reduced temperatures of uncoated surfaces by 20°C, and CoolSeal treated surfaces by 14°C, resulting in identical surface temperatures in the shade of coated and uncoated surfaces.
  • CoolSeal reduces surface temperature of asphalt during the day by an average 6°C when compared with an untreated surface.
  • CoolSeal reduced surface temperature by 1-2°C at night.
  • There is an increased ‘feels like’ temperature on treated asphalt due to the reflected solar radiation during the day.

Community Feedback

  • Perception of increased glare on treated streets.
  • Generally comparable performance for vehicle users and cyclists.
  • Perception of increased slipperiness for pedestrians.

Read the research summary findings and Click the report cover to access the full report: 

How were the trial locations chosen?

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The trial locations were primarily selected on the basis of:

  • The existing road surface being suitable i.e. no cracks or defects;
  • Streets with fewer street trees shading the road; and
  • Locations which are known to have increased local temperatures

If you are interested in exploring the thermal heat of the City, use our heat mapping tool which allows you to view and compare day and night temperatures across most of the LGA.

For further information on the Western Sydney Cool Roads Trial, contact City Strategy at


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Blacktown City Council


Campbelltown City Council


Western Sydney University

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