Did you know that the color of our house can have an impact on the indoor temperature? As evidence, researchers are interested in the effects of materials on their overall energy efficiency and their ability to reflect solar heat.
They then discovered that it was possible to maintain some freshness in our homes. But also to reduce our dependence on air conditioning in the simplest possible way: opt for white colors.
Ultra white light that reflects 98.1% of sunlight
In fact, thermoreflective paints currently on the market reflect between 80% and 90% of sunlight. Maybe that sounds good. But the researchers have pushed their work forward. Here’s how Purdue University engineers created a white color that can reflect 98.1% of sunlight! This higher percentage is important because this paint has a cooling capacity that is greater than that of conventional air conditioning systems. This atypical color is also ultra white color.
Enhancing white colors to reflect greater amounts of solar radiation is an area that researchers are increasingly exploring. Remember: “The streets of the city of Los Angeles were covered with an off-white coating (…). The streets in LA brighter with CoolSeal are on average 10 to 15 degrees cooler, “explained cbsnews in an article in 2018. In this case, it’s made of ultra-white paint and contains barium sulfate particles that allow it to reflect almost all of the sunlight, reports the New Atlas Site.
Cooling performance that exceeds conventional air conditioning systems
In their study published in the journal ACS Applied Materials & Interfaces, scientists stated that barium sulfate is a chemical compound. It is found in white photo paper and cosmetics. With a clever mix of these particles, the researchers got a very white and very reflective color.
An infrared camera image shows how a sample of the whitest white color can cool a plate or surface below room temperature. Photo credit: Purdue University / Joseph Peoples
“We looked at various commercial products, actually everything that is white (…). We found that with barium sulfate, in theory, you can really, really reflect things, which means they’re really, really white. Xiangyu Li stated in a statement posted on the purdue.edu website.
Tested outdoors, the ultra white paint kept the buildings in which it was applied at a temperature of 10.5 ° C lower than the outside temperature during the night. It also lowered the temperature by 4.5 ° C in full sunshine in the middle of the day. However, a test conducted in winter showed a decrease in surface temperature of about 10 ° C compared to 6.1 ° C inside.
In any event, Joseph Peoples, co-author of the study, claimed that “a high concentration of particles of different sizes gives the painting the broadest spectral diffusion and contributes to its unsurpassed reflectivity”. Xiulin Ruan, professor of mechanical engineering at Purdue University, said that this paint can achieve an equivalent cooling capacity of 10 kilowatts on a roof area of around 93 square meters. “Or more than the central air conditioning installed in most homes,” he says. “We did a very rough calculation (…) and we estimate that we only have to paint 1% of the earth’s surface with this color to fight global warming,” the researcher specifies in the columns of the BBC.