Just as how soccer players wear white uniforms during summer instead of black, a team of material scientists from the UCLA Samueli School of Engineering has demonstrated ways to make super white paint that can reflect 98% of incoming radiation from the Sun.
This significant advance in science shows practical ways for designing paints that, if used on rooftops and other parts of the building, could significantly decrease the costs for cooling, more than the standard "cool roof" paints can accomplish.
Traditional white paint can only reflect around 85% of solar radiation to help maintain the buildings cool, but this new super white paint can do more than that.
Super White Paint Keep Buildings Cool
Assistant professor of material science and engineering at UCLA and principal investigator of the study Aaswath Raman said that people wear a white T-shirt on a hot sunny day because it makes them feel cooler compared when they wear darker colors.
Likewise, a roof painted in whit will be cooler inside than that of a darker shade. Not only that, but white paints also reflect heat at infrared wavelengths, which a human eye cannot see, and allow the building to cool down even more through radiative cooling.
Presently, the best performing white paints used for that purpose only reflect around 85% of incoming solar radiation. The chemical in the paint absorbs the remaining radiation. The researchers showed that simple changes in the ingredients used in paints could be a significant jump, which could reflect up to 98% of incoming radiation.
Current white paints that have high solar reflectance use titanium oxide that absorbs ultraviolet and violet light. Although they are useful in sunscreen lotions, they also lead to heating under sunlight, which could get away from keeping the building cool.
So they decided to replace the titanium oxide with inexpensive and accessible ingredients like the barite, an artist's pigment, powdered polytetrafluoroethylene, or Teflon. These two can help paint reflect the UV light.
Furthermore, the scientists also refined the paint's formula by reducing polymer binders' concentration that absorbs heat.
"The potential cooling benefits this can yield may be realized in the near future because the modifications we propose are within the capabilities of the paint and coatings industry," says Jyotirmoy Mandal, a UCLA postdoctoral scholar and a Schmidt Science Fellow working in Raman's research group.
Encouraging Cool Roof Technologies for New Buildings
The authors suggested that there could be long-term implications that should be studied. These include mapping where these paints could be most useful, studying the effect of pollution the super white paints, and if this technology could affect the ability of the Earth in its ability to reflect heat from the Sun.
Moreover, municipalities and governments such as California and New York have already started encouraging the use of cool-roof technologies for new buildings.
"We hope that the work will spur future initiatives in super-white coatings for not only energy savings in buildings, but also mitigating the heat island effects of cities, and perhaps even showing a practical way that, if applied on a massive, global scale could affect climate change," said Mandal, who has studied for several years the technology of cooling paints.
But this will not be possible without the collaboration of experts in diverse fields, industries, and policy sectors.
