Ever considered a scenario when you may not need an air conditioner to stay off the seering heat around you?

How about a paint that would keep walls much cooler than outside temperature?

Well, that day may not be far away if engineers at the Purdue University in Indiana, U.S go ahead with their research. 

After a six-year study, University engineers have created a white paint that can keep surfaces up to 18 degrees Fahrenheit (-7 degree Celsius) cooler than their ambient surroundings. That's almost like a refrigerator does, but without consuming energy.

The researchers considered over 100 different material combinations, narrowed them down to 10 and tested about 50 different formulations for each material. They landed on a formulation made of calcium carbonate, an earth-abundant compound commonly found in rocks and seashells.

This compound, used as the paint’s filler, allowed the formulation to behave essentially the same as commercial white paint but with greatly enhanced cooling properties. These calcium carbonate fillers absorb almost no ultraviolet rays due to a so-called large 'band gap', a result of their atomic structure. They also have a high concentration of particles that are different sizes, allowing the paint to scatter a wider range of wavelengths.

Researchers say the paint would replace the need for air conditioning by absorbing nearly no solar energy and sending heat away from the building. Without the building heating up, air conditioning wouldn't have to kick on.

Xiulin Ruan, a Purdue professor of mechanical engineering, said: "It's very counterintuitive for a surface in direct sunlight to be cooler than the temperature your local weather station reports for that area, but we have shown this to be possible."

In a statement, the researchers noted that the paint would not only send heat away from a surface, but also away from Earth into deep space where heat travels indefinitely at the speed of light. This way, the heat does not get trapped within the atmosphere and contribute to global warming.

Xiangyu Li, a postdoctoral researcher at the Massachusetts Institute of Technology who worked on this project as a Ph.D. student in Ruan's lab, said: "We are not moving heat from the surface to the atmosphere. We are just dumping it all out into the universe, which is an infinite heat sink."

But is there research proven?

Says Ruan, "An infrared camera gives you a temperature reading just like a thermometer would to judge if someone has a fever. These readings confirmed that our paint has a lower temperature than both its surroundings and the commercial counterpart."

Cutting down on air conditioning also means using less energy produced by coal, which could lead to reduced carbon dioxide emissions