CASE STUDY: City planning - urban heat

Eastern Sydney is home to 2.7 million people, projected to increase to 3.4 million by 2041. Changing climate, with increasing temperature is one of the major issues identified for this growing region.

How did XDI help?

XDI conducted a hazard analysis limited to Heat (extreme temperature) only, analysing an area consisting of 3 case study areas.

Adaptations were applied using the temperature reductions, not the specific adaptation measure, enabling decision makers to apply adaptations within the achievable temperature reduction that suited the landscape.

XDI  was able to provide the client with a broad range of urban heat island mitigation options tailored to certain microclimates and urban contexts.

The analysis found that increasing urban heat is already resulting in adverse impacts on human health and asset performance in the case study region, with these impacts projected to intensify in the future.  The analysis included a cost benefit analysis of possible adaptation options and found that adaptation planning could significantly reduce human heat stress and infrastructure heat failure disruption.  

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Results

Based on its analysis results, XDI recommended the client consider the following:

1. Any adaptation planning to reduce heat needs to aim to reduce ambient heat by a minimum of 4°C, where possible.Certain localised hotspots will require ambient heat reduction of more than 7°C to reduce heat-related impacts.

2. The selection of effective adaptation measures for localised application will require area-specific consideration based on the existing land-use pattern i.e. to reduce the temperature of Sydney Airport area, a combination adaptation measure such as Greenery + Cool & Permeable Pavements +Water + Shading Devices, should be considered to achieve at least 4°C temperature reduction. For effectivetemperature reduction, this will require targeted and detailed land use planning, starting in the early stages of any proposed development.

3. Relevant agencies need to work in collaboration on implementing adaptations e.g. water features or irrigated surfaces, which will have an immediate and effective reduction of the heat and heat-related impact in the region.

4. Design standards should stipulate that all new assets require a minimum temperature design threshold of 50°C to address the risk of heat failure disruption. Existing assets should be retro-fitted to a minimum of 50°C during standard maintenance cycles.

Additional considerations

Human Heat Stress (HHS) events will increase by 42% – 45% by 2050 without adaptation, with approximately 485,000 human heat stress impact events in 2050.

Adaptations have short-lasting effects, and do not sufficiently reduce Human Heat Stress events.
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To have a lasting effect on heat failure and to begin reducing HHS events, 4°C cooling adaptations are necessary.
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7°C adaptation generally result in low heat failure rates across the three case study areas, although there are hotspots in Sydenham Bankstown and Airport, and HHS events persist at some locations.
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4°C adaptations result in significant health cost savings, but these savings can be roughly doubled if 7°C adaptations are implemented.