Reflective materials and irrigated trees: Study shows how to cool one of the world's hottest cities by 4.5°C

Reflective materials and irrigated trees: Study shows how to cool one of the world’s hottest cities by 4.5°C

technology By Jan 12, 2024 No Comments

Reflective Materials and Irrigated Trees: A Study on Cooling One of the World’s Hottest Cities by 4.5°C

It’s possible to significantly reduce the temperatures of a major city in a hot desert climate while reducing energy costs, a new study by UNSW Sydney shows. The findings, published in Nature Cities, detail a multi-faceted strategy to cool Saudi Arabia’s capital city by up to 4.5°C, combining highly reflective ‘super cool’ building materials developed by the High-Performance architecture Lab with irrigated greenery and energy retrofitting measures.

The Impact of Urban Heat on Cities

Extreme urban heat affects more than 450 cities worldwide, increasing Energy consumption needs and adversely impacting health, including heat-related illness and death. Riyadh, the capital of Saudi Arabia, experiences extreme heat due to its desert location, with temperatures that can exceed 50°C during summer.

Additionally, climate change and rapid urbanization are exacerbating the problem, making it imperative to find effective solutions to decrease urban temperatures and Energy consumption needs.

The Study’s Approach and Findings

For the study, the team led by UNSW researchers ran large-scale cooling climatic and Energy simulations of the Al Masiaf precinct of Riyadh. This included the evaluation of optimal strategies for lowering the city’s temperature and reducing cooling needs.

The modeling found it’s possible to decrease the outdoor temperature in the city by nearly 4.5°C during summer and improve cooling Energy conservation for the city by up to 16%. The recommended heat mitigation scenario for Riyadh includes using super cool materials in building roofs and increasing the number of irrigated trees for transpiration cooling.

Benefits of Implementing Heat Mitigation Technologies

Lowering the temperature of the city not only increases thermal comfort for people but also reduces Health issues from severe heat, decreases the concentration of pollutants, and improves human productivity. Previous research found that implementing similar cooling strategies in other cities can help reduce heat-related deaths.

Energy Impact and Retrofitting Measures

The research also simulated the Energy impact of retrofitting measures for all 3,323 buildings in Riyadh alongside heat mitigation technologies implemented at the urban scale. It was found that combining the optimal cooling technologies with Energy retrofitting options could decrease the cooling demand by up to 35%.

This represents a substantial reduction to the Energy needs for Riyadh, helping further reduce costs associated with cooling for the city while improving the quality of life for the local population.

Implementation and Future Outlook

The researchers now hope to work with the Royal Commission of Riyadh to begin implementing the tailored heat mitigation plan in the city, which would be the largest of its kind in the world. Once implemented at the city scale, these advanced heat mitigation technologies will deliver important Health, sustainability, and economic outcomes for the city for years to come.


The study by UNSW Sydney has demonstrated the tremendous impact advanced heat mitigation technologies and techniques can have to reduce urban overheating, decrease cooling needs, and improve lives. It has provided valuable insights into addressing the challenges posed by extreme urban heat, particularly in hot desert climates, and offers a promising path forward for creating cooler and more sustainable cities.

By leveraging reflective materials, irrigated trees, and Energy retrofitting measures, cities facing similar challenges can take inspiration from this study to develop tailored strategies and enhance the livability and sustainability of urban environments.

Source: phys

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