This video was created in
partnership with Bill Gates, inspired by his new book “How
to Avoid a Climate Disaster.” You can find out more about
how we can all work together to avoid a climate disaster in the link below. [♪ INTRO] One of the basic human needs is shelter. And over the short time humans have been on Earth, we’ve come up with a lot of
different ways to shelter ourselves — from mud huts, to wooden buildings, to
the towering skyscrapers of many cities. But many of those materials
aren’t as strong as they could be. And the ones that are can have
an outsized impact on our planet. So now, architects and engineers are
turning to nature for inspiration for more resilient materials — stuff
that improves on what we use now, and that often minimizes the
impact we have on this planet. From cement that acts like sweat glands
to glass that mimics fish scales, here are some biology-inspired materials that could
transform the future of construction. One major threat to buildings is fire. When a fire sweeps through a structure, it often means a lot of new
construction is on the way. That often means more cement and steel — and making both of those involves
a lot of greenhouse gases. Thankfully, there are all kinds of ways
to make a building safer in a fire. In addition to fire alarms,
extinguishers, and sprinklers, you can add fireproof materials to
the building’s support structure to keep it from failing, as well as
to the walls, floors, and ceilings, to keep fire from spreading. But these are all passive methods.
And because they’re extra materials, they add extra cost and take extra energy to make. So it would be helpful if
there were materials that could actively prevent fire damage, plus be supportive. Well, researchers in China
may have invented just that, using human sweat glands for inspiration. In a paper published in 2019,
they shared their development of a fire-retardant cement blend,
which stops fire from damaging a building’s structure sort of like
how sweat keeps human bodies cool. The cement is a blend of three materials:
a set of compounds named APP-PER-EN, some reinforcing fibers, and a concrete binder. Under normal conditions,
it does what you’d expect — it holds up the weight of a building. But if there’s a fire, it goes through four
stages to stop that fire in its tracks. First, as temperatures rise between
100 and 160 degrees Celsius, the reinforcing fibers and
the APP-PER-EN start to melt — kind of like how sweat glands make
sweat when you start to get warm. When the temperature reaches
above 170 degrees Celsius, micro-channels and cracks form. Then, temperatures above 300 degrees
cause the APP-PER-EN to foam, filling the micro-channels and cracks and forming a
fire insulation layer like sweat on skin. And finally, as the insulating layer forms,
gases get released, including water vapor. This mimics the cooling mechanism of sweat — how when sweat evaporates, it takes
some of the body heat with it.
This insulating layer protects the
cement from falling under high heat by taking on a honeycomb shape. This adds strength while also
insulating against heat transfer using the air trapped in the honeycombs.
I know! It sounds like science fiction! Then, after a fire, you can remove the
honeycomb layer and repair the material instead of having to replace the entire
cement structure, saving costs and resources. Next, speaking of heat, humans have
been passively heating their homes with sunlight for thousands of years. But we couldn’t control the release
of this heat until the 20th century. Only then did we invent collectors like
thermal walls, which could absorb heat from sunlight and slowly release it over
time, keeping us warm throughout the day. The trouble is, most of these
collectors are made from rigid, heavy materials, which means
their uses are limited. So engineers are looking to polar bears as
inspiration for textile-like solar collectors, which would be more efficient, lightweight,
and flexible than their predecessors. Polar bears have white fur and black skin
that work together as a natural solar collector and insulator, which helps them
stay warm in the extreme cold of the Arctic. Their outer fur is actually
transparent — it only looks white because of the way it’s structured. That transparency allows the
sunlight to reach their dark skin, which converts the sun’s energy into warmth. Another layer of dense underfur close
to their skin is spaced just right, creating little pockets of air that
trap heat close to the bear’s body. In fact, they radiate so little heat that
they’re almost invisible to infrared detectors. The surface of their coats looks the
same temperature as their environment! Inspired by this heat-trapping ability,
researchers based in Germany and Austria shared a new type of solar
collector in a 2015 paper. They imagine it being used as part of solar power, but this general idea could
also help with buildings, too. The collector has two layers of
transparent plastic and silicone that let light pass through to the bottom layer. These layers are positioned around a
centimeter apart, trapping a layer of air between them and minimizing heat
loss like a polar bear’s underfur. The bottom layer is black silicone,
which absorbs the sun’s light and converts it to heat. And the warm air can be pumped out
by a fan and stored for later use. Early tests show that this collector
is able to generate temperatures of up to 150 degrees Celsius —
although right now that only works when it’s in direct sunlight. Still, while those extreme temperatures
might be helpful for solar power, that’s also not the kind of
heat you’d need in a building. So, this idea could really come in handy, especially as textile-based
buildings become more mainstream. These futuristic buildings are
constructed from lightweight materials stretched over a frame or woven together, and are making everything about
a building more sustainable, including its design, materials, usage, and
even how it’s recycled at the end of its life. Adding a polar bear-inspired heating
system would make them even more versatile. Buildings also need to stay
comfortable in hot weather, though — and traditional cooling systems
aren’t always the most efficient way of managing a building’s temperature. Also, heating and cooling
systems account for a lot of the greenhouse gases we emit as a planet. Architects in the U.S. may have
come up with a more efficient way of regulating a building’s temperature, though, and once again they have drawn on
inspiration from the human body. In 2011, they released a
prototype of a building exterior modeled after a biological process
that’s similar to a thermostat — if a thermostat could control
more than just temperature. That process is called homeostasis,
and many organisms use it to keep their bodies functioning
within pre-set limits, like an ideal temperature range or fluid balance. Basically, it allows things
to remain stable on the inside even as conditions change on the outside. The team designed a glass building facade inspired by the way human
muscles maintain homeostasis, by expanding and contracting to regulate
heat as they work inside our bodies. Similarly, the facade helps regulate
the internal temperature of the building by opening and closing itself. The exterior of the building is
made up of two layers of glass, and sandwiched between them
are swirling silver lines. Those lines are made up of ribbons
of a special type of polymer that can have an electric current applied to it. It also has a silver coating that
distributes an electrical charge across the entire surface. When sunlight warms the silver coating, the polymer expands and shades the building. Then, when the building cools off, the polymer
contracts and allows more light inside. That way, the building responds to changing
environmental conditions throughout the day, helping manage energy use in
a more efficient and sustainable way. Now, this tech might not be best for
places where you want extra sunlight — like, in the middle of a cold winter. But for a lot of climates, it
could be a great step forward. Next up: concrete. Like we mentioned earlier, making concrete
is a major contributor to climate change, but sometimes, it seems like there’s
only so much you can do about that. Like, if a building is
damaged during an earthquake… well, you’re gonna have to build another one. Some teams are looking into
concrete recipes or processes that are overall better for the planet,
but some are taking another route. Like, researchers at Purdue University
are trying to strengthen concrete instead… by using cracks. More specifically, in 2018, they
developed 3-D printed cement structures inspired by the mantis shrimp. Mantis shrimp hit their prey
with a club-like front claw at an extremely high speed,
which generates a lot of force. But even then, that claw does
not crumble under pressure, thanks to the way the shell’s
microscopic layers are arranged. The layers are stacked in a spiral, each
layer slightly offset from the next. When stressed, cracks form in the
microscopic layers, but the twisted structure keeps the cracks from spreading
through the entire club. Specifically, the spiral forces
the cracks to form parallel, or side to side within a layer, instead
of perpendicular — or top to bottom. And every time a crack has to change direction, it requires a lot of force to do so, which
causes it to lose some of its energy. If a crack does spread top to bottom, the
next layer vibrates as the crack reaches it, absorbing the energy from the crack, keeping
it from traveling into the next layer. Ultimately, these tiny twisting cracks
stop the club from falling apart, by preventing larger cracks from forming
that would compromise the structure. Using this club for inspiration, the
researchers 3D printed a cement paste that’s laid out in a similar spiral design. Poured cement is brittle and when stressed, large cracks can form and
lead to catastrophic failure. Not so with this 3D-printed material.
Here, tiny cracks are stopped so they don’t spread throughout the
layers, just like with the mantis shrimp. So the concrete is inherently stronger. The goal is to eventually use this
type of material to build more earthquake-resistant structures.
And that means less wasted concrete! Finally, windows. Windows can be an
incredibly important part of a building on an aesthetic level. But since they’re
so fragile, they’re also the weakest. Except, by mimicking an overlapping
pattern found in fish scales, researchers may have found a way to
improve the strength of laminated glass, while still preserving the
ability to see through it. Laminated glass is created by sandwiching a soft, polymer-based layer between
two layers of regular glass. This keeps the glass together
if it breaks, making it safer. But it is not stronger — or at least
it wasn’t until researchers in Canada discovered a way to improve
the lamination process. In a paper published in 2018,
they outlined their process for strengthening glass with
a new lamination technique. They started by coating two
sheets of glass with a flexible, heat-resistant polymer film, and then etched
straight lines into the glass with a laser. The polymer film holds the glass
together through the etching process. Then, they laid the sheets of
glass on top of each other, with another layer of flexible
polymer sandwiched between. They also rotated the top sheet of
glass so the etched lines go in the opposite direction — known
as cross-ply architecture — and that gives the glass added
strength and flexibility. When this type of glass is stressed, the
cross-ply architecture and stretchy polymer middle work together to help the glass
be stretchy and tough instead of brittle. Testing revealed this glass to be
50 times tougher than regular glass, while still maintaining its see-through qualities. If this kind of glass spread, that would
mean stronger, safer windows that might need to be replaced less often — all
thanks to a pattern inspired by fish. Nature has been around for a long time,
and we’re only beginning to tap into the engineering insights you can get
from billions of years of evolution. But with materials like these, we’re
looking at a future of buildings that are safer, more resilient,
and better for our planet. When you think about things
contributing to climate change, construction materials might
not be what comes to mind first. But making things like cement, steel, and
plastic releases a lot of greenhouse gases. And if you want to keep learning more
about how we can make those things better, you can read Bill Gates’s new book
“How to Avoid a Climate Disaster.” It talks about manufacturing, but also food, heating and cooling, transportation, and more. If you’re interested, you can find out more about how we can all work together to avoid
a climate disaster in the link below. [♪ OUTRO]
