Making white paint whiter has created a highly efficient way to cool buildings and objects, reducing the need for mechanical cooling and potentially making huge savings in energy.

Purdue University set out to help curb global warming, with the Indiana-based school creating the whitest paint so far made.

“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 10KW. That’s more powerful than the central air conditioners used by most houses,” said Xiulin Ruan, a Purdue professor of mechanical engineering.

Typical commercial white paint gets warmer rather than cooler. Paints on the market that are designed to reject heat reflect only 80-90 per cent of sunlight and therefore cannot make surfaces cooler than their surroundings, but twith the new paint researchers demonstrated outdoors that the paint can keep surfaces 19 degrees Fahrenheit cooler than their ambient surroundings at night. It can also cool surfaces 8 degrees Fahrenheit below their surroundings under strong sunlight during noon hours.

The paint's solar reflectance is so effective, it even worked in the middle of winter. During an outdoor test with an ambient temperature of 43 degrees Fahrenheit, the paint still managed to lower the sample temperature by 18 degrees Fahrenheit.

This white paint is the result of six years of research building on attempts going back to the 1970s to develop radiative cooling paint as a feasible alternative to traditional air conditioners.

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