An innovative building material with properties similar to those of a chameleon is capable of changing colour, but not only. It can also change the amount of heat it absorbs or releases depending on the outside temperature.
During hot days, this material is capable of releasing up to 92% infrared heat that holds, helping to keep the inside of a building cool. In winter, however, the material it only emits 7% of its infrared, helping to keep the building warm.
A material that behaves like a person
“We have created an energy-efficient way to manage building temperatures. A similar approach to what a person would take. A person who puts on an extra layer when it's cold and takes one off when it's hot,” explains the Assistant Professor Po-Chun Hsu from the University of Chicago.
This type of smart material allows us to maintain a comfortable temperature in buildings without having to use large quantities of the energy.
How the chameleon material is born
The nonflammable building material created by Hsu and colleagues is “electrochromic.” What does it mean? It contains a layer that can take two conformations: solid copper that retains most of the infrared heat or an aqueous solution that emits infrared.
A device connected to it uses a small amount of electricity to induce chemical shifting between states by depositing the copper in a thin film or by removing it.
In their paper (that I link to you here), the researchers detailed how the device can quickly and reversibly switch between the metallic and liquid states. The ability to switch from one conformation to another remained efficient even after 1.800 state transitions.
What performance are we talking about?
The researchers developed scenarios to demonstrate how their material could reduce energy costs in buildings in different cities.
According to their calculations, the use of electricity to activate the electrochromic changes of the chameleon material would be less than 0,2% of total consumption of the building's electricity. But it could save you money 8,4% of annual energy consumption.
Chameleon material: next steps
Hsu's team has so far only produced pieces of material around 6cm in diameter, but they have ambitions to use these fragments to create increasingly larger panels.
Among the next steps, the researchers are evaluating the possibility of customizing the material with different color shades. The “aqueous phase” is transparent and would allow a wide range of colors to be used without compromising the chameleon material's ability to absorb infrared rays.
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