Engineers from Purdue University, Indiana, have developed a white paint that can keep surfaces up to 18°F cooler than their ambient surroundings. The paint doesn't absorb any solar energy and sends heat away from the building.
It would work almost like a refrigerator, and that too, without the need for electricity. As the paint doesn't heat up the building, it would drastically reduce the need for air conditioning.
The most intriguing part is that the paint would not only send heat away from a surface, but it would send it into deep space, far away from Earth. Thus, the heat wouldn't get trapped within the atmosphere and contribute to global warming.
When implemented on a large scale, to a variety of surfaces, including roads, rooftops, and cars, this paint would actually cool down the Earth's surface.
Other commercial heat-rejecting paints reflect only 80%-90% of sunlight and cannot achieve temperatures below their surroundings. However, this white paint reflects 95.5% sunlight and efficiently radiates infrared heat.
The revolutionary paint was developed based on a six-year study, where the researchers considered over 100 different material combinations, narrowed them down to ten and tested about 50 different formulations for each material. They zeroed-in on a formulation made of calcium carbonate, which is used as the paint's filler and allows the formulation to behave just like commercial white paint but with greatly enhanced cooling properties.
These calcium carbonate fillers have a large band gap due to their atomic structure; thus, they absorb almost no ultraviolet rays. They also have a high concentration of different-sized particles that allow the paint to scatter a wider range of wavelengths.
Coming to its commercial viability, the paint would be both cheaper to produce than its commercial alternative and would also save on cooling requirements. It is basically creating free air conditioning by reflecting sunlight and offsetting heat gains from inside a building.