The cold blast of an air conditioner can be a welcome relief as temperatures soar, but "A/C" units require large amounts of energy and can leak potent greenhouse gases. Today, scientists report an eco-friendly alternative—a plant-based film that gets cooler when exposed to sunlight and comes in a variety of textures and bright, iridescent colors. The material could someday keep buildings, cars and other structures cool without requiring external power.
This article has been reviewed according to Science X's editorial process and policies . Editors have highlighted the following attributes while ensuring the content's credibility: A colorful, textured bi-layer film made from plant-based materials cools down when it's in the sun. Credit: Qingchen Shen The researchers will present their results at the spring meeting of the American Chemical Society (ACS). ACS Spring 2023 is a hybrid meeting being held virtually and in-person March 26–30. "To make materials that remain cooler than the air around them during the day, you need something that reflects a lot of solar light and doesn't absorb it, which would transform energy from the light into heat," says Silvia Vignolini, Ph.D., the project's principal investigator. "There are only a few materials that have this property, and adding color pigments would typically undo their cooling effects," Vignolini adds. Passive daytime radiative cooling (PDRC) is the ability of a surface to emit its own heat into space without it being absorbed by the air or atmosphere. The result is a surface that, without using any electrical power, can become several degrees colder than the air around it. When used on buildings or other structures, materials that promote this effect can help limit the use of air conditioning and other power-intensive cooling methods. Some paints and films currently in development can achieve PDRC, but most of them are white or have a mirrored finish, says Qingchen Shen, Ph.D., who is presenting the work at the meeting. Both Vignolini and Shen are at Cambridge…