Researchers at Purdue University have created a new type of white ‘cooling paint’ to help cool buildings, reducing use of air conditioning and other appliances.
Global energy use for cooling appliances is expected to grow by 90% by 2050. With contemporary global warming, air conditioning and refrigeration have become critically important. According to the Global Status Report published by the UN, buildings and construction together account for about 39% of global energy-related carbon dioxide emissions. Methods of passive cooling (without the use of energy) are proving to be vital in the coming decades, with white painted ‘cool roofs’ becoming more common in urban areas with hotter climates.
A ‘cool roof’ is a rooftop created using highly reflective white paint, tiles, or shingles, designed to reflect more sunlight and absorb less heat than a standard rooftop - similar to wearing light-coloured clothing to keep cool on a hot day.
Material experts at Purdue University thought to take this concept further by developing a white paint able to reflect 95.5% of sunlight and reduce temperatures by 1.7°C compared to surrounding ambient conditions. Studies suggest that painting buildings with this ‘cooling paint’ could help cool entire cities.
A variety of particle sizes help to scatter more sunlight
Several radiative cooling paints have been developed in the past; however, many were formed of potentially harmful agents, including titanium dioxide. The new study employs the use of calcium carbonate fillers, which are cheaper, more sustainable, and absorb less ultraviolet light than previous developments. The paint is also made up of a variety of particle sizes to help scatter more sunlight, making it a more effective cooling agent. Researchers have found that the paint could prevent outdoor electrical systems from overheating, and that it is compatible with the manufacturing processes of commercial paint.
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