{"id":3235,"date":"2021-11-16T22:00:00","date_gmt":"2021-11-16T22:00:00","guid":{"rendered":"https:\/\/modernsciences.org\/staging\/4414\/?p=3235"},"modified":"2021-11-03T02:43:58","modified_gmt":"2021-11-03T02:43:58","slug":"newly-developed-smart-material-can-help-heat-and-cool-buildings","status":"publish","type":"post","link":"https:\/\/modernsciences.org\/staging\/4414\/newly-developed-smart-material-can-help-heat-and-cool-buildings\/","title":{"rendered":"Newly-Developed Smart Material Can Help Heat and Cool Buildings"},"content":{"rendered":"\n

In simple terms, electrochromic <\/em>materials are capable of changing their coloration and transparency to things like solar radiation when they\u2019re exposed to an electric field. Once you take the electric field out of the system, these new materials should be able to return to their initial state.<\/p>\n\n\n\n

Perhaps the most famous example of these new materials are those that can be seen, quite literally, in electrochromic sunglasses; they\u2019re \u201cspecial\u201d in a sense that their lenses have electrochromic material on them, which can then be darkened on demand.<\/p>\n\n\n\n

In truth, these materials can easily let some visible light through with its inherent technologies. Of course, doing this is by no means an easy task. Current electrochromic materials involve two thin electrode plates serving as \u201cbread\u201d to an electrochromic \u201csandwich;\u201d spread between the two electrodes is an electrically responsive material, which forms the functional aspect of the whole thing.<\/p>\n\n\n\n

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Sunglasses like these can sometimes have electrochromic material applied to their lenses; in return, these special sunglasses can turn \u201cdarker\u201d when they\u2019re worn in areas with bright sunlight. (Lokesh et al\/Wikimedia Commons, 2018) <\/figcaption><\/figure><\/div>\n\n\n\n

Problem is, the setup is functionally inadequate to allow the pass-through of radiative heat from the Sun. After all, addressing these issues could open new avenues for the burgeoning technology as part of our increasingly-imminent future of \u201csmart\u201d buildings, as evidenced by studies into cooling buildings via salt solutions<\/a> and easing up on electric bills by using the power of the house inhabitants\u2019 footsteps<\/a>.<\/p>\n\n\n\n

It is thus important for scientists to think of ways to improve these technologies that allow both visible light and radiative heat to pass through\u2014a feat that may now be made possible due to new developments in the field published in the journal ACS Energy Letters<\/em>. The effort was led by Po-Chun Hsu, assistant professor of mechanical engineering at the Thomas Lord Department of Mechanical Engineering and Materials Science, Duke University.<\/p>\n\n\n\n

Said Hsu in a statement to Duke\u2019s Pratt School of Engineering news website: \u201cWe have demonstrated the very first electrochromic device that can switch between solar heating and radiative cooling. Our electrochromic tuning method does not have any moving parts and is continuously tunable.\u201d<\/p>\n\n\n\n

The obstacles start with the search for applicable electrically-conductive materials, as transparency to visible light and radiative heat are often competing properties in compatible materials like polymers and metals. Hsu and team figured out a workaround, though: they simply made their own, and they sought for the help of plasmonics<\/em> to do it.<\/p>\n\n\n\n

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By changing the direction of flow of electrons from one to the other, Hsu and team manage to change the transparency of their novel material to both visible light and radiative heat\u2014essential aspects to a potential electrochromic material. (Rao et al, 2021) <\/figcaption><\/figure><\/div>\n\n\n\n

Plasmonics involves the manipulation, generation, and detection of signals at optical frequencies in nanometer-scale interfaces. In the case of Hsu and team, they made use of metal nanoparticles suspended in a liquid electrolyte. For the two thin electrodes, the research team used sheets of graphene topped with a gold grid. The gold acts as a sort-of electron \u201chighway,\u201d helping to shuttle electrons to and from its surroundings.<\/p>\n\n\n\n

Once an electric field is applied to the material, the metal nanoparticles pool and stick to the top electrode, blocking out visible light and radiative heat by reflecting them back to the outside\u2014essentially its cooling<\/em> mode. Once the flow of electrons is reversed, the nanoparticles return to the electrolyte solution, rendering the entire electrochromic material roughly transparent again, letting both light and heat pass through\u2014thus, its heating <\/em>mode.<\/p>\n\n\n\n

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A basic demonstration by Hsu and team showcase the potential of their new electrochromic material at both keeping both visible light and its accompanying heat out and at letting both of them through\u2014all with the help of applying electricity to it. (Rao et al, 2021) <\/figcaption><\/figure><\/div>\n\n\n\n

At the time of publication, Hsu and team\u2019s work took roughly two (2) minutes to transition between its darkened and transparent state. \u201cThe device would spend many hours in one state or the other out in the real world, so losing a couple minutes of efficiency during the transition is just a drop in the bucket,\u201d said Hsu.<\/p>\n\n\n\n

The next steps for Hsu and team include increasing the efficiency of their entire setup, as the current technology experiences an efficiency drop after a few dozen use cycles. They also hope to improve the novel technology\u2019s solar reflectivity while in cooling mode. They also hope to see a potential future for their material as coatings in future buildings, to help them heat up and cool down without adding much to the building\u2019s electrical usage.<\/p>\n\n\n\n

“I can envision this sort of technology forming a sort of envelope or facade for buildings to passively heat and cool them, greatly reducing the amount of energy our HVAC [heating, ventilation and air conditioning] systems have to consume,” said Hsu in a statement to news source EurekAlert!<\/em>. “I\u2019m confident in this work and think its future direction is very promising.”<\/p>\n\n\n\n

References<\/h2>\n\n\n\n