How cool is that? New white paint “more powerful” than air conditioning
Scientists have developed a paint that reflects over 98% of sunlight, which they say makes it more efficient than some air conditioning units. His credentials in energy saving could help tackle the climate crisis
American engineers have created a paint so white that coating buildings, they say, could one day reduce the need for air conditioning. Reducing energy consumption in buildings is essential to tackle the climate crisis.
Purdue University, Indiana, has built on efforts to develop “radiative cooling paint” that date back 50 years.
After six years of research and studying over 100 materials, they developed a paint so effective at reflecting sunlight, it cools surfaces below surrounding ambient temperatures.
How cool is that? Well, they put a number on it. Purdue Studies showed that at the height of the midday sun, painted surfaces were 4.5 degrees Celsius cooler than their surroundings. At night it got 10 degrees Celsius colder.
“If you were to use this paint to cover a roof area of about 1,000 square feet, we estimate that you could get 10 kilowatts of cooling power. It’s more powerful than the central air conditioners used by most homes, ”said Xiulin Ruan (main photo), professor of mechanical engineering at Purdue.
His team found that commercial “heat rejecting” paints only reflect about 80 to 90 percent of sunlight – and actually get hotter than cold.
White paint has long been used on buildings in Greece to reflect sunlight. Image: Clark Van Der Beken
Their paint, which reflects percent, uses high concentrations of barium sulfate particles – the same chemical compound used in photo paper – to achieve its dazzling shine. A wide variety of particle sizes means that more of the sun’s light spectrum, including infrared heat, is diffused.
Purdue scientists believe that an even whiter hue may be possible by increasing the concentration of particles, although they will have to overcome the increased brittleness that this implies.
Main picture: Professor Xiulin Ruan with a sample of the whitest paint ever recorded. Credit: Prudue University / Jared Pike