Cooling cities down with fountains?

 An interesting article in the Guardian

The secret to more livable, cooler Australian cities may lie with the ancient Romans and a network of fountains like the Trevi and those in Piazza Navona, a new report on tackling urban heat has found.

Rome has a network of 2,000 fountains which draw huge crowds daily to enjoy their cooling effects in the dense city.

Sydney planners should take note, says the president of the Western Sydney Regional Organisation of Councils, Barry Calvert.

According to the Cooling Western Sydney study undertaken jointly by the University of New South Wales and Sydney Water, while greenery does have a cooling effect, the most effective results come from a combination of water-based technologies – these include fountains – and cool material technologies such as cool roofs and pavements.

The study used sophisticated modelling and expertise in microclimatic research to evaluate the impact of urban heat mitigation technologies (greenery, water and cool materials) in western Sydney.

It then modelled specific sites in western Sydney to assess the impact of specific technologies, including reducing energy costs and heat-related deaths, which are up to three times higher in western Sydney during extreme heat events.

The NSW government is currently planning the new Western Parkland City around the second airport at Badgerys Creek, 60km west of the CBD.

The Aerotropolis, now renamed Bradfield, will eventually be home to 1.5 million people, but with temperatures 6C to 10C higher than the coast, the region presents a challenge to ensure it does not become a heat island, with an unhealthy microclimate.

The emphasis so far has been on creating a tree canopy, though the early plans also aim to retain creeks and waterways and avoid building in flood plains.

The new study urges a focus on water infrastructure to enable greater cooling and the use of materials that have a high reflective (albedo) score.

That will require planning to ensure the reuse of water and measures such as banning black roofs and dark road surfaces.

The study used experimental data about the urban heat island effect from 101 Australian and Asian cities to understand how the phenomenon worked.

The study found that higher reductions in temperatures have been achieved by the scenario of water-based technologies combined with cool materials.

“More specifically, it was found that increasing the global albedo to 0.5 by the large scale application of cool materials and implementing water-based technologies may result in an average air temperature reduction of 1.5C in the area, with local reductions close to the water reaching 10C,” the study said.


Based on data from the summer of 2016-17, when there were severe hot spells, the modelling showed that combined use of cool materials and water could lower the cumulative heat-related deaths in the far west from 14 to approximately 7.5 deaths per 100,000 inhabitants.

Closer to the coast, heat-related deaths could be lowered to approximately five deaths per 100,000 inhabitants.

“While greenery does have a cooling effect, the study shows the most effective urban heat mitigation technologies are those incorporating a combination of water-based technologies with cool materials,” the study found.

Calvert said investments in water supply services and infrastructure could help cities become more resilient to global warming and heatwaves.

“This could consist of such things as installing or repairing fountains for drinking and cooling, and for cooling spaces by using water spray fountains, along with cooling by wetting streets,” he said.

“Fountains can decrease surrounding air temperatures by 3C and their cooling effect can be felt up to 35 metres away,” Calvert said.

“Fountains also have social value. Children play in fountains and people enjoy fountains in parks and squares, and they serve as meeting places.

“Who knows? Maybe it’s time we turned greater Sydney into a city of fountains?” Calvert said.

They key facts in the article:

• Fountains can reduce air temperature by 3 degrees C (5.4 F)
• Their cooling effect can be felt up to 35 metres (115 feet) away
• A combination of cool materials and fountains can reduce temperatures over large areas by 1.5 C, and smaller areas by 10 C

If we combined fountains *and* trees *and* pale roofs, we might almost eliminate the urban heat island effect.   I wrote a piece where researchers said that a street lined with large trees could cut temperatures by 5 degrees C compared to adjacent areas without trees---see "The Magic of Trees".