While ultra black materials today can absorb more than 99.96 percent sunlight, this new super white coat can reflect 95.5 percent of all photons that hit it.
Instead of warming under direct light, objects painted with this new acrylic material can remain colder than their surroundings even under the sun, a new energy-efficient way to control the temperature inside buildings. Can give permission.
Other “heat rejecting paints” we currently have can only reflect 80 to 90 percent of the sunlight and cannot achieve lower-than-ambient temperatures.
“It is an ongoing task to develop a low-ambient radiation cooling solution that provides a convenient single-layer particle-matrix paint form and high reliability,” says mechanical engineer Shilin Rouan of Purdue University in Indiana.
“This is important for the widespread application of radiation cooling and reducing the global warming effect.”
On summer days, many modern buildings rely on air conditioning units that push heat from inside the building outside. This, along with the extra heat generated through the intense energy needed to achieve cooling, contributes to turning cities into “heat islands” and further increases global warming.
Radioactive cooling is a passive technique that reflects heat from a building in space, but is much harder than radiant heating.
Since the 1970s, scientists have been trying to figure out how to reflect enough sunlight so that passive cooling is more effective than an active air conditioner.
Recently, some have even tried to put together a ‘reverse solar panel’, which can capture some of that outgoing heat and turn it into energy even at night.
But right now these are just concepts, and it is unclear whether such devices can actually work outside of a simulation.
A more viable approach might be to photograph residential and commercial buildings in Super White, at least in the near future.
The new acrylic paint was made using calcium carbonate filler at a high particle concentration and a wide range of sizes, which can efficiently scatter all wavelengths of the solar spectrum.
The paint’s matrix also has a vibrational resonance peak, which ensures that a high amount of heat is reflected outward – at a much higher rate than other cooling paints.
During a two-day field trial at different locations and under different weather conditions, the researchers tested the radiative cooling capabilities of the paint and found that it could scatter 95.5 percent of the sunlight, 10 ° C at night, and ambient temperatures. At least 1.7 ° C below the temperature below ambient temperature. In the afternoon
Compared to coated surfaces with the same thickness of commercial white paint, objects covered in calcium carbonate paint maintained significantly lower temperatures in the infrared footage.
What’s more, this paint brushes and dries in the same way, and is abrasion resistant, waterproof and can withstand external weathering for at least three weeks, although tests are currently underway.
“Our paint is compatible with the manufacturing process of commercial paint, and the cost can be comparable or even lower,” Ruan says.
“The key is to ensure the reliability of the paint so that it is viable in long-term outdoor applications.”
The authors state that their paint is “the best radiation cooling performance reported”, although they acknowledge that in the course of reviewing their results, another team published a paper in which high-grade broad band gap particles in cooling paint Concentrations must be included.
They also suggest the inclusion of fluorocarbon-based polymers, which show high resistance to weathering.
“Many traditional white paints, while engineered for durability, experience drop in solar reflectance over time,” other recent papers reveal.
“Materials such as fluoropolymer-based binders can extend the reflectivity lifetime and thus lower the average cost over the year.”
Creating a single-layer paint that can directly reflect heat into space without the need for energy input would be a major victory for the climate crisis, as cooling is typically driven by fossil fuels and a major overall impact on global warming Does matter.
The new paint still has to undergo some further tests, but patents have already been filed. The name has not been revealed yet.
The study was published in Cell report physics.
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