A combination of cooling technologies and techniques could reduce the temperature and energy needs of Riyadh, Saudi Arabia.
It’s possible to significantly reduce the temperatures of a major city in a hot desert climate while reducing energy costs, according to a new study by the University of New South Wales Sydney (UNSW).
The findings, published in Nature Cities, provides 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 study, which was conducted in collaboration with the Royal Commission of Riyadh, is the first to investigate the large-scale energy benefits of modern heat mitigation technologies when implemented in a city.
UNSW Scientia Professor Mattheos Santamouris, Anita Lawrence chair in High-Performance Architecture and senior author of the study, said the project demonstrates the tremendous impact advanced heat mitigation technologies and techniques can have to reduce urban overheating, decrease cooling needs, and improve lives.
Santamouris specialises in developing heat mitigation technologies and strategies to decrease urban temperatures in 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, is one such city. Situated in the centre of a desert, it is one of the hottest cities in the world, with temperatures that can exceed 50°C during summer.
Furthermore, climate change and rapid urbanisation are increasing the magnitude of overheating.
“Limited greenery and large artificial surfaces made of conventional building materials like asphalt and concrete trap heat, meaning the city continues to heat up,” he said.
“Additional heat from car pollution and industrial activities also increases the city’s temperature.”
For the study, the team led by UNSW researchers ran large-scale cooling climatic and energy simulations of the Al Masiaf precinct of Riyadh, including the energy performance of 3323 urban buildings, under eight different heat mitigation scenarios to evaluate optimal strategies for lowering the temperature of the city and reducing cooling needs.
The modelling, which considered different combinations of super cool materials, vegetation types and energy retrofitting levels, found it’s possible to decrease the outdoor temperature in the city by nearly 4.5°C during summer.
The strategy would also improve cooling energy conservation for the city by up to 16 per cent.
The recommended heat mitigation (or cooling) scenario for Riyadh includes using super cool materials implemented in the roof of the buildings and more than doubling the number of irrigated trees to improve transpiration cooling.
On the contrary, a blind implementation of urban cooling techniques not based on detailed and advanced scientific optimisation, like the use of non-irrigated greenery, may result in a substantial increase in the city’s temperature.
“By implementing the right combination of advanced heat mitigation technologies and techniques, it is possible to decrease the ambient temperature at the precinct scale,” Santamouris said.
“For a sweltering city the size of Riyadh, significantly reducing cooling needs is also tremendous for sustainability.”
The research also simulated the energy impact of retrofitting measures for all 3323 buildings alongside heat mitigation technologies implemented at the urban scale.
Combining the optimal cooling technologies with energy retrofitting options – namely, improving the building envelope through better windows, insulation, solar and cool roofs – could decrease the cooling demand by up to 35 per cent.
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.