Parramatta Cool Roads Trial (Western Sydney)
14,700m² treated across 12 sites · 6°C surface cooling · urban heat island mitigation
CoolSeal reduced surface temperatures by 6°C but did not reduce ambient air temperature at trial scale — suggesting city-scale deployment (as in Phoenix, ID_19) is needed for air temperature effects. A companion case study to ID_19.
A 2019–21 trial applied CoolSeal reflective coating to 14,700m² of road across 12 sites in three Western Sydney councils, achieving 6°C surface temperature reductions on hot summer days. Confirmed surface cooling benefits but found no systematic reduction in ambient air temperature — useful counter-evidence to complement ID_19 (Phoenix, which found greater success at larger deployment scale).
Climate drivers
Impacts
Adaptation measures
- CoolSeal reflective pavement coating
- Surface temperature monitoring
- Environmental monitoring programme
Assets affected
Investment
AU$15m application cost (at trial scale; significantly lower at Phoenix/city scale)
Band: £1m–£10m
Delivery period
—
- Heat stress is the largest natural disruptor to communities in the Greater Sydney Basin. Increasing heat is recognised as the largest risk to local populations and economies across Greater Western Sydney . Climate change is projected to increase this risk.
- Black asphalt has a low albedo (surface reflectivity) of just 0.03-0.04, with a high thermal mass and storage capacity for heat. Consequently, asphalt pavements absorb heat during the day making the surrounding areas hotter by elevating both daytime and overnight surface temperatures through the release of this heat . This increases Urban Heat Island effects.
- Unshaded asphalt road surfacing (pavement) and intensifying day and nighttime summer temperatures both create risks to environmental and public health, including heat-related illness, which are exacerbated by the Urban Heat Island effect. Higher temperatures contribute to increased energy consumption and GHG emissions in cities .
- Approximately a third of the outer suburbs of Sydney are thermally dense black asphalt, which can reach a surface temperature of 75°C .
- For 10 days in the summer of 2018/19 Parramatta City communities experienced daytime maximum air temperatures of over 35°C .
- The adaptation measure of ‘CoolSeal’ was trialled to reduce surface and air temperatures in Western Sydney.
Ref: ID_22 · City of Parramatta Cool Roads Trial Project (1) · Curated & verified by HIVE
Applicable to UK cities experiencing urban heat island intensification in summer heatwaves. This trial provides both the evidence for surface cooling and important caveats on scale thresholds — effective at city scale, not at trial-patch scale. Read alongside ID_19 (Phoenix) for the full picture.
UK contexts
Applicable to UK urban areas
Transfer to other sectors (AI)