As the world warms due to climate change, architects and engineers are altering the way they design and construct buildings to reduce carbon emissions and lower energy consumption. According to a new study, a team of University of Maryland (UMD) researchers have developed a “cooling glass” that can reduce temperatures within a building without electricity.

The researchers claim the glass answers the need for passive cooling materials that are resistant to harsh environments, especially in regions that are rapidly warming due to climate change. The glass coating features a microporous glass silicon dioxide framework embedded with aluminum oxide nanoparticles. The approach produces a material with high solar reflectance and selective long-wavelength infrared emission.

The researchers claim in the study, A Solution-Processed Radiative Cooling Glass, that the specialized coating can decrease the temperature of underlying materials by 3.5 degrees Celsius at midday, even in high-humidity conditions. They add it can also reduce the annual carbon emissions of a mid-rise apartment building by 10%.

The coating operates in two ways:

  • It reflects up to 99% of solar radiation to prevent buildings from absorbing heat; and
  • It emits heat as longwave infrared radiation into space.
  • In a phenomenon recognized as “radiative cooling,” space essentially functions as a heat sink for buildings. This entails leveraging the cooling glass design and the atmospheric transparency window—a segment of the electromagnetic spectrum that traverses the atmosphere without elevating its temperature—to expel substantial amounts of heat into space.

    Distinguishing from prior attempts at cooling coatings, the glass is environmentally robust—capable of withstanding exposure to water, ultraviolet radiation, dirt and even flames, and enduring temperatures of up to 1,000 degrees Celsius. Its applicability extends to tile, brick and metal surfaces, meaning it can be highly scalable and adaptable for widespread use, researchers claim.

    The researchers told UMD’s Maryland Today that they used finely ground glass particles as a binder. This allowed them to avoid polymers and enhance their long-term durability outdoors. They chose the particle size to maximize the emission of infrared heat while simultaneously reflecting sunlight.

    Liangbing Hu, the study’s lead author, emphasized the glass coating is not just a new product; it constitutes a crucial component of the solution to climate change, Hu suggests.

    “By cutting down on air conditioning use, we’re taking big steps toward using less energy and reducing our carbon footprint,” he told Maryland Today. “It shows how new technology can help us build a cooler, greener world.”

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