March 4, 2025
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Green open spaces can play a significant role in cooling cities. Shade and evapotranspiration from vegetation create cooler microclimates. Green spaces also provide other benefits like flood management, recreation and amenity benefits, biodiversity and cleaner air.
Although important, it’s often difficult to value these health and other benefits in economic terms, because there is no direct market price. In such cases, the value of benefits can be estimated by taking information captured at one place and time to make inferences about the economic value of goods and services at another place and time.
A recent rapid review by Alluvium and Water Sensitive Cities Australia draws together evidence from Southern Australia and tropical cities in Asia. The studies reviewed highlighted that estimating the value of these cooling benefits often hinges on 2 questions:
- How much cooling can reasonably be expected of parks of different sizes?
- How far does this cooling extend beyond the park boundaries?
For example:
- A small, irrigated 1.5 ha park in Melbourne can provide an average 1oC air temperature cooling effect (up to 3oC) during a hot summer, compared with surrounding streets. This cooling effect extended 0.5 ‘park widths’ beyond the park.
- Cooling effects of parks in Asian cities can extend around 150m downwind of the park (or 1 ‘park width’ for a larger park).
The reviewed studies included existing parks, natural areas and green spaces ranging from lot scale, small parks (1–20 ha) to large parks (hundreds of ha). They commonly reported changes in land surface temperature (e.g. when using Landsat methods) or air temperature (e.g. when reporting more localised benefits of shading).
A fact sheet provides details about the review, outlines the limitations and lists all the papers included in the review.
