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New building materials that reduce urban temperatures and neutralize the effects of climate change will be produced through a research partnership between UNSW Sydney and the University of Sydney.

The roofs, sidewalks and siding of so-called super cool buildings reflect rather than absorb solar energy. They can reduce temperature spikes in our cities by up to four degrees, enough to save lives, says Scientia Professor Mattheos (Mat) Santamouris.

“One of the major issues in the built environment is urban overheating or regional climate change,” says Professor Anita Lawrence of High Performance Architecture. “As our cities heat up, heat-related morbidity and mortality are increasing.”

In 2020, 593 and 391 people died from heat-related deaths in Melbourne and Sydney respectively, a substantial increase from 289 and 176 in 2007, according to the State of the environment in Australia.


Read more: ‘Coolbit’ aims for personalized comfort advice in specific environments


Countering the urban heat island effect

Overpopulation and rapid urbanization are turning our cities into urban heat islands, says Professor Santamouris. Human activity – waste heat from industry, cars and air conditioners – is driving up temperatures in cities, making them noticeably warmer than surrounding areas. This concerns more than 500 cities in the world.

“Our way of building [also] increases the temperature of our cities. We are using [heat-absorbing materials like] asphalt, we use concrete,” says Professor Santamouris.

Super cold roofs and sidewalks, on the other hand, reduce the energy needed for cooling. This in turn decreases carbon dioxide emissions which increase the magnitude of climate change. It makes our cities more economical, environmentally friendly and livable, he says.

The next-generation materials were tested as part of a study to reduce temperatures in Australian cities, primarily as part of an ARC Discovery project.

The study found that introducing super cool materials along with other heat mitigation strategies, such as increasing greenery and shade, could save around ten lives per 100,000 population per year. .

“Under the sun, [with] 42 degrees ambient temperature, the [super cool] the surface temperature of the materials was 25°C. It’s natural air conditioning without the expenditure of energy – super cold materials,” explains the energy physicist.

“And all of these new technologies and materials were developed here in Australia.”

Promote energy conservation with the government

Professor Santamouris and his team are partnering with the Department of Industry, Science, Enterprise and Research (DISER) on two projects to promote energy efficiency in the built environment.

The team will provide cost-benefit analyzes and scientific documentation on the adoption of chilled roofs in Australia, and on ways to improve energy efficiency in new and existing commercial buildings, such as office buildings, aged care facilities, hotels, day care centers and shopping malls.

With around 40% of total energy consumption in developed countries attributable to buildings, there is huge potential for impact, says Professor Santamouris.

“Reducing energy consumption and associated greenhouse gas emissions through energy conservation measures is key to meeting energy and climate goals in cities,” he said.


Read more: A “bad economic bet”: what will climate change inaction cost Australia?


Princely project a win for Australian technology and knowledge exchange

Professor Santamouris is applying his research to reduce temperatures in Riyadh, Saudi Arabia, one of the hottest cities in the world. The Riyadh Royal Commission has engaged its team to develop a comprehensive heat mitigation plan, the largest of its kind.

The project recognizes Australia’s cutting-edge research and technology in the field and delivers significant health, sustainability and economic results. They use computational tools with rich urban datasets to model building performance at the urban scale, identify energy retrofits, and inform urban planning.

Extensive aerial surveillance using aircraft and infrared technologies, carried out by industry partner National Drones, will map the city’s thermal conditions. While high-resolution large-scale simulations of the city will evaluate different scenarios to decipher optimal strategies.

The project also takes into account vegetation, water, city ventilation and the introduction of super cool materials. The team is coordinating similar studies for the cities of Dubai, UAE; Kolkata, India; and Kuala Lumpur, Malaysia in collaboration with local researchers.

Scientific graph of heat attenuation in Riyadh

Cold materials were applied in the case of attenuation and a reduction in ambient temperature was observed. Excerpt from project report for Cooling Riyadh. Picture: Provided.

A fairer energy master plan

Energy conservation also has a knock-on effect on equity, says Professor Santamouris. Today, 20% of the population in developed countries cannot afford to meet their energy needs due to low incomes and poor quality housing, he says.

“The temperature difference between east and west Sydney in the summer, for example, can be up to 10 degrees. In a distance of 60 kilometers, it’s great,” he said.

“It has a huge impact on the quality of life for people in Western Sydney. They spend nearly 100% more energy on cooling. They have much higher death rates.

The less energy we need, the greater the thermal satisfaction for everyone, he says. And that’s the end goal for him. The most powerful research revolves around pragmatic altruism, he says.

“Research must advance knowledge, help solve existing problems and fill existing gaps in knowledge to improve quality of life,” he says. “He must advance the global good for the betterment of society, to protect the lives of citizens.”

Professor Santamouris is ranked as the World’s Most Cited Building and Construction Scientist for 2019 and 2020 at Stanford’s Meta-Research Innovation Center. He and his team are involved in more than 200 large-scale heat mitigation projects around the world in Europe, America, Asia and Australia.