This Material Might Change How We Cool Our Houses Forever

this video is brought to you by Squarespace this tiny beetle is the whitest known insect on Earth and it may hold the key to the future of energy efficient buildings in a groundbreaking study published in science researchers from the city University of Hong Kong have unveiled an Innovative ultra white ceramic composite inspired by the cocalis beetle it promises to revolutionize the ways buildings are called the material is capable of reflecting up to 99.6% of solar radiation incident on a building setting a new record for Passive radiative cooling materials and substantially reducing the need for air conditioning which currently accounts for 10% of all energy used on the planet but canab Beal really teach us how to better designed buildings and can this new material really hold up to its potential promise this is one of the coolest noon intended material developments I've seen in a while and as a nanop physicist this tugs on all of the awesome things about nature in by a tech that I love so let's Dive In White is a tough color for nature to produce there are a few different approaches that it tries to take for example some organisms try to produce white coloration using biominerals the shells of mollusks are often white due to the presence of calcium carbonate that they can produce organically polar bear fur is white because it's Hollow and lacks any pigmentation at all make it almost behave like an optical fiber capable of scattering light in all directions but the cocalis beetle uses a trick that I think is way more interesting geometry at the scale of nanophysics you might have heard of other animals that can create vibrant colors using structure rather than pigmentation the blue morpho butterfly is a fascinating example of this phenomenon to produce its striking iridescent blue wings each Wing scale of the blue morph butterfly contains a multitude of tiny tree likee structures these structures are nanosized in scale and made up of layers of kiten a common material in insect exoskeletons and are arranged in a way that produces an array of holes across the wing called Nano holes or sometimes called nanopores the spacing and orientation of these Nano holes are incredibly precise with dimensions and separations comparable to the wavelengths of visible light when light strikes the surface of a blue morpho's Wing It interacts with these Nano structures causing the light to interfere as it scatters the holes are designed in a spacing and geometry that most of the colors of light reflected will cancel out with each other in a process called deconstructive interference where the peaks of one reflection meet the troughs of another that is all except for a particular shimmering blue color that the butterfly wings displays this particular set of wavelengths is Amplified through constructive interference and as this color comes from structure rather than from pigmentation even when the blue morpho butterfly is dead when pigments otherwise would have faded its wings will still reflect the same Brilliant Blue this mechanism for color creation is reasonably common in nature we also see it in the peacock the hummingbird feathers even some spiders squid and octopus species but producing color by removing all but a few wavelength is one thing white however where all wavelengths are scattered equally at incredibly High efficiency is a much harder challenge but how has this Beetle overcome this difficulty to produce one of the most brilliant colors of white on the planet the cocalis beetle is a native of Southeast Asia and yes I do have to be careful every single time I say his name because I might get banned by YouTube it produces its strikingly white color one of the brightest in nature using ultra thin scales that cover its body also made of kiten that same material we talked about in the blue morpho butterfly but here rather than creating holes to produce color these scales are made up of a network of filament like structures by using scanning electron microscopy or sem the researchers found that the white areas of the beetle contain 15,000 scales per square cm these scales are shaped like teardrops and are around 220 Micron long and about 60 Micron wide the filaments contained in these scales have a diameter of around 25 of a micron which is about 300 times thinner than a human hair and comprise a highly connected random network of kiten with a filling fraction of only 60% meaning the other 40% is air and typically have diameters of only2 of a millimeter by running spectroscopic characterization which essentially looks at the light reflected from a material it revealed that the scale covered skeletons exhibit an average reflectivity of about 60% which is incredibly high for a naturally occurring material and we aren't exactly sure how these are produced but the leading theory seems to be through a process analogous to spinodal decomposition a mechanism where a solution of two or more components spontaneously separates into different phases this process is sometimes called unmixing this produces a strange self assembling network of filaments within the scale of the Beatles recent archers believe that at some point one of these materials then slowly evaporates through the surface of the scale leaving a network of tubules suspended in air this Nano structure that remains is highly optimized to scatter light of all colors evenly which as I said is no mean feet the optical properties of a scattering material depend on a few considerations the ones that seem to be optimized here are across two length scales the scattering mean-free path which is the average distance between scattering events and the transport mean-free path which is the length that the light has to travel before its propagation Direction its direction of travel is randomized in simulations that researchers have run in other literature the resultant structure that nature is able to produce here was found to be Incredibly Close to perfectly optimized for white light reflection where researchers did find some improvements that could be achieved mathematically the changes required to the material to do so would have likely either reduced its strength or increased its sensitivity to temperature fluctuations that may have caused the material to crack over time for whatever the reason for producing this incredibly white material whether it's mating warning Predators or just to look flashy Nature has optimized the cyphus beetle scale to an incredibly High degree and it was from this inspiration that researchers at City University of Hong Kong took their Direction and produced a piece of technology that is absolutely amazing but before I talk about it I have have to thank today's sponsor Squarespace I've said it before I'll say it again Squarespace is my absolute favorite Web building platform last week we started building a new website for The Venture Capital fund that we are launching to support science breakthroughs we built out the framework of the website in about 2 days from Members areas portfolios to news sections the tools that Squarespace gives you to quickly test ideas and Designs are incredibly powerful we honestly took longer deciding a name for the company than building the website Squarespace gives you a fast easy to maintain and greatl looking internet presence that gives you both credibility and a platform for your message and Mission if you're in the market for a website I could not recommend more checking out www.squarespace.com and if you want to save 10% on your first purchase of a website or domain use the code Dr Ben miles thank you Squarespace for existing now back to the video in this breakthrough paper published just last week in the Journal of science called hierarchically structured passive radiative cooling ceramic with high solar reflectivity which is a a catchy title I've ever I've heard one the City University of Hong Kong researchers unveiled their ceramic material taking inspiration from the cocalis beetle they introduced a material that was engineered with a hierarchically porous structure that led to a near ideal solar reflectivity which just means an ability to reflect photons from the Sun of 99.6% this breaks the world record for a material of this kind in the paper they describe that this material is fabricated from a three component solution of polyether sulfone or PES n methyl 2 peridone or nmp and Alpha alumina the material is produced by after casting it on a flat substrate the material was immersed in an ethanol bath the material then unixes itself in a process called phase inversion which takes place as the ethanol diffuses into the casting and dissolves any npm that it comes in contact with following cining to remove any PES this process forms a random porous Network carrying alumina particles throughout producing a structure that looks very similar to The cocis Beetles scales and although this manufacturing process might sound complicated this is pretty easy in terms of fabrication the grand scheme of things it doesn't require either Precision instrumentation or fine control of the parameters what researchers did find is that by manipulating the alumin concentration in the phase inversion precursor the team was able to produce a very short transport me free path meaning that photons are highly efficiently scattered giving the material its high R solar value of 99.6% and alumin as a material Choice here is important because the band gap of alumin which essentially means the distance between the veence electrons and the conduction band electrons of alpha alumina is about seven electron volts and that means that it is higher than most energetic solar photons in simple terms what that means is that light from the sun doesn't have enough enough energy to excite electrons in alumin essentially meaning that rather than absorbing these photons they are reflected giving the material its very low Extinction coefficient and that is what makes its high R solar its high reflectivity possible to put in perspective just how reflective it is silver has a r solar of about 89.5% making this material more reflective than the average household mirror white pigmented paint That's commonly used on the outside of buildings is about 88.6% and white commercial tiles are about 76.2% so this material by all measures and metrics is incredibly white and it also boasts an excellent daytime cooling performance which means that it can reduce the energy consumption needed to keep an internal space cool to demonstrate the materials cooling performance the research team built a custom-designed thermal setup essentially a pretended house to compare it against a commonly used white commercial tile as a control through a continuous 84h hour measurement the cooling ceramic consistently maintained a temperature of 3.8 C below the Ambient Air Temperature with a maximum subambient air temperature recorded of 8.8 C in contrast the white commercial tiles only maintained a below ambient condition at night specifically what this translated to is that the roof with this new cooling ceramic material on top of it was almost 5° C cooler than the commercial alternative at High Noon and obviously doing the important step of Translating that into Energy savings the cooling ceramic tiled model house consumed between 26.8 and 19% less energy when trying to maintain a constant set temperature of either 25 23 or 20° C this is a significant reduction in energy requirement and as a result costs this ability to maintain these temperatures cooler than ambient conditions is another f fasinating property that comes from a lumina's high emissivity of 96.5% within the atmospheric window and what that means is that this material is capable of shedding heat as photons and the energy of those photons are such that they radiate in a gap in the atmosphere meaning that the atmosphere isn't very good at then reabsorbing that heat and keeping it close to the material making it lose heat incredibly effectively far superior to any other state-of-the-art material or counterpart applying this material into the built environment which just means into construction into homes into offices if these properties prove out it could be an absolute game Cher in thermal management either it could be applied to roofs or walls as a retrofit cladding material or potentially as a paint solution and obviously it requires no power to make these cooling properties function when the research team went to look at its temperature performance it also performs above and beyond other materials capable of withstanding temperature es up to 1,000° probably if applied to most buildings what that means is that it would increase the fire safety rating of the average building taking this idea of fire safety one step further the authors in this paper suggest that actually most commercial tiles prevent roof surfaces in the event of a fire from being effectively wetted by fire hoses because as they get superheated the water that is incident on them immediately vaporizes in a process called the lien Frost effect you might have seen this effect before if you put water in a hot pan it sort of floats around on a cloud of its own steam but what this means is that it isn't evaporating effectively or quickly and it isn't pulling heat away from the material which in the event of a fire is a bad thing in contrast the research team's cooling ceramic exhibits super hydr filicity attracting and actually wetting the ceramic surface and letting water funnel into its porous structure as a result the research team found that the Li and frost effect which usually happens around 280° for most commercial tiles only occurs at temperatures above 800° C making it easier to put out a fire as a final point if this material is not amazing enough to you already if white is too boring the material can apparently be produced in other colors and patterns by adding extra layers at probably the reduction to some extent of some of its Effectiveness the performance and the ease of manufacturer of this material if it proves out is absolutely going to put it in a class of its own obviously we need to wait for other research teams to confirm the results or for someone to try to commercialize it to understand if it really floats within the marketplace but for now I think this is really exciting I'm an optical physicist to me the optical approach and the data that I've seen feels totally reasonable I am less familiar with the materials used here so I will defer to your or the internet's best judgment about the cost of goods or the environmental impacts or the other considerations we've not made in this video but for now I don't think this is a Holy Grail this is more of a holy nature and I think that is way cooler thanks very much for watching I'll see you next time

Channel: Dr Ben Miles

Views: 277,512

Keywords: science, future, breakthrough

Id: T2Sn9QG68WI

Length: 15min 8sec (908 seconds)

Published: Wed Nov 29 2023