Sustainability Matters Feb/Mar 2022

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Cool roofs, pavements to reduce heat island effects


verpopulation and rapid urbanisation are driving up temperatures, transforming cities into urban heat islands. “One of the major

problems in the built environment is urban overheating, or regional climatic change,” said Mattheos (Mat) Santamouris, Anita Lawrence Professor of High Performance Architecture at the University of New South Wales. Human activity — waste heat from industry, cars and air conditioners — makes cities significantly warmer than surrounding areas. This affects more than 500 cities worldwide. “As our cities heat up, heat-related morbidity and mortality rise,” he said. In 2020, 593 and 391 people died from heatrelated deaths in Melbourne and Sydney respectively, a substantial increase from 289 and 176 in 2007, according to the Australia State of Environment.

Radiative coolers To combat this issue, UNSW Sydney and the University of Sydney have teamed up to create building materials — super cool roofs, pavements and coatings for buildings — that reflect rather than absorb solar energy. They can reduce peak temperatures in our cities by up to four degrees, enough to save lives, Professor Santamouris said. “The way we build [also] increases the temperature of our cities. We’re using [heatabsorbing materials like] asphalt, we’re using concrete,” Professor Santamouris said. Super cool roofs and pavements by contrast reduce the energy needed for cooling. This in turn decreases carbon dioxide emissions that increase the magnitude of climate change. This makes our cities more economical, environmentally friendly and livable, he said.

8 Sustainability Matters - Feb/Mar 2022