You have to read it three or four times and it will still sound confusing. Researchers at the University of Colorado Boulder created a material, which is able to keep buildings cool. In case it should be applied one day, it might be possible to reduce loads of energy-intensive air conditioning systems. This would be worthwhile due to the enormous energy consumptions of air-conditioning units all over the world. Reason enough to take a closer look at their findings. The scalable manufactured metamaterial is able to lower building temperatures independently even when they are exposed to direct sunlight. The thin plastic film cools buildings by reflecting the incoming solar rays into the atmosphere. At the same time, it is possible to shed the building’s heat as infrared thermal radiation. These properties are, allegedly, not found in nature.
The Thin Plastic Film Cools Buildings by Emitting Thermal Energy and Barely Absorbing Sunlight
“Just 10 to 20 square meters of this material on the rooftop could nicely cool down a single-family house in summer,” said Gang Tan, an associate professor in the University of Wyoming’s Department of Civil and Architectural Engineering.
“The key advantage of this technology is that it works 24/7 with no electricity or water usage,” said Yang “We’re excited about the opportunity to explore potential uses in the power industry, aerospace, agriculture and more.”
Reflecting Any Incoming Solar Ray by Having a Means of Escape for Infrared Radiation
With a thickness of 50 micrometers, the glass-polymer hybrid material with its passive cooling feature possesses resonant polar dielectric microspheres, which are randomly embedded in a polymeric matrix. This improvement results in a completely transparent material property and infrared emissivity above 0.93. A very thin silver layer, added on the entire material surface, results in a demonstrated noon-time radiative cooling power of 93 Watt per square meter when exposed to direct sunlight. This is the secret how the thin plastic film cools buildings without demanding energy compared to an air conditioning system, which, however, is more an active than passive means of cooling.
“Both the glass-polymer metamaterial formation and the silver coating are manufactured at scale on roll-to-roll processes,” added Ronggui Yang, also a professor of mechanical engineering and a Fellow of the American Society of Mechanical Engineers.
Questions are arising
Before this material is really applied on buildings, it is recommended to find answers to the following questions. It is, of course, impossible to violate the laws of physics. For that reason, the thin plastic film with its shining silver look has always to be at the very top of the building surface so that it is able to reflect the impinging radiation. This naturally begs the question of how does the building surface look like if it is covered with a layer of this silvery plastic film? It probably doesn’t matter in case it is only attached on the roof, since it is not visible from the ground. But if the entire facade of a building is wrapped with a layer of shiny silver, it is recommended to get ready for critical comments unless it is a part of the holistic building design. However, in case it shall be applied to more than one building or even a whole quarter, in order to achieve considerable energy savings, decision-makers start worrying about how it will look like to stand between buildings with smooth and silvery surfaces only. It probably conveys the impression of being in an open-air mirror cabinet?
How much maintenance is needed in order to keep this material reflecting strongly? How does the efficiency change over a period of application of five years or more? It is assumed that if it is applied in several regions in the world, the material will be exposed to all weather conditions, such as sunshine, ice, rain, moisture, snow, high and low temperatures as well as strong wind.
Materials science and materials engineering are a considerable mainstay regarding a sustainable urban future. Again and again, new discoveries and material improvements demonstrate the enormous potential and opportunities. Whether new solar panels storing the sun’s energy, whether creating self-shading windows, or whether investigating lime as energy storage system: Imaginary unexplored possibilities in conjunction with the spirit of research and entrepreneurship ensure further surprising improvements.
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