About the Cool Suburbs Assessment

Urban design and heat resilience

Learn more about strategies for managing urban heat through urban planning and design and how these inform the assessment approach.

The role of urban design in heat management 

Hotter temperatures affect communities of all sizes in NSW. In cities, urbanisation exacerbates the impacts of heat through increased density, reduced green spaces, and the conversion of natural land into heat-absorbing surfaces. Factors such as material selection, wind patterns, and local topography contribute to this urban heat island effect (UHI), increasing accumulation of heat.

In rural areas, the impact of urban heat islands may be less, but a hotter climate overall combined with limited access to cooling infrastructure and water sources, increases risk of heat-related illnesses and negative impacts on agriculture and ecosystems.

Overall, it is equally important to reduce impacts of extreme heat and heatwaves for locations with dense or limited urban development. Addressing the urban heat island effect (UHI) is crucial and urban design must seek to minimise UHI as a key contributor to hot temperatures in both urban areas and rural towns.

Management strategies for urban heat

Mitigating urban heat risks has been a goal for decision makers around the world for several decades. In the past, policies to mitigate urban heat have often focused on single drivers. For example, cool roof initiatives to reduce building temperature, tree planting for localised cooling, and greater irrigation of open space for neighbourhood cooling.

While these solutions can be effective, they are not able to support precinct-scale cooling outcomes. Approaches that focus only on reducing surface temperatures and lowering ambient temperature will not prevent extreme heat events. To be successful in addressing this complex issue takes an integrated approach that considers a range of factors contributing to heat increase including:

• The local climate context, including the effects of climate change
• Development site condition e.g. greenfield or brownfield sites
• Development scale e.g. masterplan
• Development typology e.g. building, residential home, or park

Taking a broader and more integrated approach offers decision-makers a set of measures that can be applied at multiple scales and tailored to local climate conditions.

Benefits of a resilience approach to urban cooling

Given historic temperature extremes as well as projected increases from a changing climate, heat impacts cannot be mitigated only by reducing the average (ambient) temperature. It is essential to ensure people have capacity to adapt to higher and extreme temperatures, and that community and emergency services are able to support the most vulnerable when extreme heat occurs. Low-carbon and renewable-based design strategies are also required to minimise contributions to climate change which over time will amplify urban heat and extreme weather events.

A resilience approach is designed to support these outcomes, using strategies to minimise the impacts of intense shocks such as heatwaves and the ongoing stress of frequent hot and very hot weather. Any intervention that aims to be successful in improving community resilience to heat must include measures to achieve the following objectives:

• Mitigate heat e.g., greening, high albedo roofs etc.
• Allow people and infrastructure to adapt to a hotter climate e.g. developing energy efficient buildings, PV and energy storage features.
• Provide appropriate social infrastructure, including designated heat refuges (e.g. pools, air-conditioned libraries etc.) and response approaches to heat-stress (e.g. emergency services, ambulances etc.).

Heat resilience and the Cool Suburbs Assessment

While the Cool Suburbs Assessment project has taken a resilience approach to address heat, the focus of the assessment is on measures to reduce heat and to help people adapt to heat. This is because planning and design can play the greatest role in this two steps. Developing cool cities will also require work with other stakeholders to ensure that the broader range of awareness raising and respond measures are also implemented in current and new developments.

Initiatives recommended and rewarded through the Cool Suburbs Assessment can be expected to:

• Reduce residual urban heat to help mitigate increasing average temperatures.
• Support adaptation to help address periods of hot weather where reduction initiatives fall short.
• Ensure response elements are available to support community resilience in periods of extreme heat.

How the assessment supports development decisions

Through the planning and development process, a range of decisions impact upon who manages the impacts of urban heat, what is required and how this is achieved.

This includes:

• Government decision-making: Strategic decisions that guide the requirements and performance of a development or community.
• Developer decision-making: Operational decisions that reflect changes in market demands, regulatory requirements, or economic outcomes.

The measures implemented or considered through these decision-making processes lead to variable outcomes that are reflected by changing regulatory landscapes and their enforcement, as well as market demands and technology. After these outcomes are implemented in place, government, business, and local communities are required to manage their residual impacts or benefits. Therefore, influencing these decision points through the application of a tool should focus on addressing residual risk as opposed to linking directly with dynamic elements of the planning process.

The resilience approach used in developing the CST facilitates place-based assessment that recognises the challenges of urban heat as they play out in a community across a range of scales. The ability to specify local conditions and context for a given location (including the climate region and the physical composition) mean that the measures recommended through the CST assessment will remain relevant and effective at addressing urban heat, regardless of the local policy context. This place-based logic has been made primary in the tool, helping to facilitate the flow of evidence-based measures to address urban heat throughout the planning and development process.

In NSW, there are a number of ways for new developments to progress through state and local government planning processes. The CST is particularly relevant to development application and assessment. It is also relevant to strategic planning, particularly within the Urban Design Credits. Examples of intervention points relevant to the CST are summarised in Table 1.