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Radiative cooling: will ultra-white paint replace air-conditioning?
From the U.S. the new ultra-white paint that can cool down spaces
A group of engineers from Purdue University in the United States have created an ultra-white paint that can reflect up to 98.1% of the sun’s rays and lower the temperature of the painted surfaces by 7 degrees Celsius compared to the ambient temperature.
The results of the research are significant considering that the radiative cooling paints currently being sold in the global market only reflect up to 80-90% of the sun’s rays and absorb UV light, meaning that they are unable to cool down surfaces below the outside temperature.
The American university had already tested the ultra-white paint with excellent results back in October 2020 but it has definitely achieved a new level with the new version. The technology not only lowers the temperature and percentage of reflected solar light, but also delivers benefits in terms of sustainability, because used to cool down buildings, it will be possible to dispense with air conditioning, resulting in lower energy use and reduced effects on global warming.
Purdue University professor of mechanical engineering Xiulin Ruan provides a big picture insight into the potential of this new ultra-white paint: “If you were to use this paint to cover a roof area of about 1,000 square feet, we estimate that you could get a cooling power of 10 kilowatts. That’s more powerful than the central air conditioners used by most houses".
There are primarily two features that give the paint its extreme whiteness. First, the paint has a very high concentration of barium sulphate, a chemical compound used to whiten photographic paper and cosmetics. Second, the particles in the compound are all different sizes. The amount of sunlight scattered by each particle depends on particle size so a wider range of particle sizes allows the paint to scatter more of the light spectrum from the sun.
The ultra-white paint created by the engineers from Purdue comes after six years of research into the first experiments conducted back in the ’70s, whose goal was to develop a radiative cooling paint as an alternative to air conditioners. After 50 years of experiments, we seem to be getting closer to that goal.
The results of the research are significant considering that the radiative cooling paints currently being sold in the global market only reflect up to 80-90% of the sun’s rays and absorb UV light, meaning that they are unable to cool down surfaces below the outside temperature.
The American university had already tested the ultra-white paint with excellent results back in October 2020 but it has definitely achieved a new level with the new version. The technology not only lowers the temperature and percentage of reflected solar light, but also delivers benefits in terms of sustainability, because used to cool down buildings, it will be possible to dispense with air conditioning, resulting in lower energy use and reduced effects on global warming.
Purdue University professor of mechanical engineering Xiulin Ruan provides a big picture insight into the potential of this new ultra-white paint: “If you were to use this paint to cover a roof area of about 1,000 square feet, we estimate that you could get a cooling power of 10 kilowatts. That’s more powerful than the central air conditioners used by most houses".
There are primarily two features that give the paint its extreme whiteness. First, the paint has a very high concentration of barium sulphate, a chemical compound used to whiten photographic paper and cosmetics. Second, the particles in the compound are all different sizes. The amount of sunlight scattered by each particle depends on particle size so a wider range of particle sizes allows the paint to scatter more of the light spectrum from the sun.
The ultra-white paint created by the engineers from Purdue comes after six years of research into the first experiments conducted back in the ’70s, whose goal was to develop a radiative cooling paint as an alternative to air conditioners. After 50 years of experiments, we seem to be getting closer to that goal.
