Climate change is one topic guaranteed to get Mat Santamouris hot under the collar. As a Professor of High-Performance Architecture at the University of New South Wales (UNSW) and a past professor at the University of Athens, Santamouris has studied different ways to cool the planet for most of his academic career.
Involved with more than 200 largescale heat-mitigation projects across Europe, the Americas, Asia and Australia, his work includes developing thermochromic materials such as paint that changes colour with the temperature to keep places cool in summer and warm in winter; nanotechnology that gives surfaces a much lower temperature than the ambient temperature; and ultra reflective photonic materials that absorb less heat.
The multi award-winning energy physicist says overpopulation, rapid urbanisation and waste heat from industry, cars and air conditioners, are transforming our cities into urban heat islands. Affecting more than 450 cities globally, he says extreme urban heat is the most documented climate change phenomenon because it contributes to increasing energy consumption needs and adversely impacts health.
The problem is exacerbated because there is no one cause impacting all cities, he says.
“Take for example Western Sydney. It is overheated, and during summer presents about 10 degrees higher temperatures compared to the eastern suburbs. In a distance of 60 kilometers, that’s tremendous. This is because of its proximity to the desert. This is the main problem. It’s not because we lack greenery, have very high anthropogenic heat or we’re not using the proper materials. These contribute, but it’s not the main reason.”
THE NEXT GENERATION OF MATERIALS
Santamouris is now leading a project partnership between UNSW Sydney and the University of Sydney that will produce new building materials capable of reducing urban temperatures and counteracting the effects of climate change.
The so-called ‘super cool’ roofs, pavements and coatings for buildings can reduce peak temperatures in our cities by up to four degrees. They work by reducing the energy needed for cooling, decreasing carbon-dioxide emissions that increase the magnitude of climate change.
“Under the sun, with 42 degrees ambient temperature, the super cool materials’ surface temperature was 25 degrees.” Because they reflect, rather than absorb solar energy, widescale adoption of such materials have the potential to make cities more economical, environmentally friendly and liveable, he says.
“These materials are very reflective. They reflect, but the most important property is that these materials emit heat at wavelengths which really can escape the earth’s atmosphere and go directly to space. We can send the excess heat of the materials directly to space because our planet has a so-called atmospheric window, where the heat may escape. This is the mechanism that really keeps the earth cool. It’s a natural air conditioner without expending any energy.”
More importantly, the technology may also save lives. According to the Australian Institute of Health and Welfare, 984 people across Melbourne and Sydney died from heat-related illnesses in 2020, a significant jump from the 465 heat-related deaths that occurred across the same cities thirteen years earlier in 2007.
One study found introducing super cool materials with other heat mitigating strategies, such as increased greenery and shade, could save around 10 lives per year, per 100,000 residents.
THE WAY FORWARD
The next stage of the project will see Santamouris’ team provide cost-benefit analyses and scientific documentation on the adoption of cool roofs in Australia, alongside suggestions on how to improve energy efficiency in existing commercial buildings.
Santamouris says the project team have finalised the first and second generation of the materials and is now working with some “big” Australian companies to commercialise these products. Early work on the project suggests these materials cost about 10 per cent more than their conventional counterparts. However, Santamouris argues this is a small price to pay when compared to the cost of inactivity due to climatic change.
With around 40 percent of the total energy consumption in developed nations attributable to buildings, there is huge potential for impact, he says.
“The cost of overheating in cities is close to $480 billion per year. By 2050 this is going to be $2.5 trillion per year. Therefore, the cost to upgrade the technology is minimal compared to the penalty we’ll have to pay.”
MORE WORK NEEDED
But making super cool roofs, pavements and coatings more readily available only addresses part of the issue of urban overheating, Santamouris says. Ideally what is needed is an economic mechanism whereby those who contribute to increasing the temperature in cities, for example, by their greenhouse gas emissions are financially penalised, and those who help to decrease the temperature through eco-friendly materials or plantings are incentivised.
“If we don’t monetize the cost of the overheating, we’ll never solve the problem. We need really to dare and take measures which will help to decrease the temperature. If not, the cost for the next generations or even for the present generations will be tremendous.”
