As global temperatures continue to rise, keeping buildings cool has become one of the biggest challenges for cities around the world. Air conditioners provide relief, but they consume huge amounts of electricity and release additional heat into the environment, making cities even hotter. Now, researchers at the University of Pennsylvania (Penn) have found an innovative solution inspired by one of nature’s largest land animals—the African elephant.
By studying the elephant’s unique skin, scientists have created a low-cost cement tile that captures water and slowly releases it through evaporation, naturally cooling buildings without fans, compressors or high energy consumption. Their findings, published in Advanced Materials, could pave the way for greener, more energy-efficient buildings.
Nature’s Cooling Secret
Humans rely on sweating to cool down. When sweat evaporates from our skin, it removes heat and lowers body temperature. This natural cooling process is highly efficient.
However, elephants do not sweat. Despite living in the scorching heat of the African savanna, they manage to stay cool. Researchers discovered that the secret lies in the deep cracks and wrinkles covering their thick skin.
According to Dorit Aviv, Associate Professor of Architecture at Penn’s Weitzman School of Design, these cracks act like tiny water reservoirs. When elephants spray themselves with water or mud, the liquid gets trapped inside the network of cracks instead of running off immediately. The trapped water evaporates slowly over time, providing continuous cooling.
This remarkable natural system inspired researchers to ask a simple question: What if buildings could cool themselves the same way?
Buildings That “Sweat” Without Sweat
Unlike living creatures, buildings cannot sweat. Most walls and roofs simply absorb sunlight, becoming extremely hot during the day. Traditional cooling systems rely on electricity-powered air conditioners to remove this heat.
The Penn research team developed a new cement-based tile that mimics elephant skin. Instead of smooth surfaces, these tiles contain carefully engineered microscopic cracks that trap water and spread it evenly across the surface.
As the stored water slowly evaporates, it removes heat from the building, reducing surface temperatures naturally. This process requires no electricity, moving parts or refrigerants, making it a completely passive cooling system.
Impressive Cooling Performance
The researchers tested their elephant-inspired tiles under infrared heating while periodically adding water.
The results were remarkable.
The temperature beneath the new cooling tiles remained around 32°C (89.6°F).
For comparison:
Standard cracked stucco reached 42°C (107.6°F).
Smooth commercial stucco climbed to 52°C (125.6°F).
In other words, the new material kept surfaces between 6°C and 11°C cooler than conventional building materials.
Such temperature reductions could significantly reduce the need for air conditioning, lowering electricity bills and greenhouse gas emissions.
Why Air Conditioning Isn't Enough
Today, buildings account for nearly 40% of total energy consumption, with heating, cooling and ventilation making up almost half of that usage.
Air conditioners solve one problem while creating another.
They consume large amounts of electricity, much of which still comes from fossil fuels. At the same time, they release indoor heat outside, contributing to the urban heat island effect that makes cities even warmer.
The elephant-inspired cement tiles avoid these problems entirely by cooling the building's exterior before heat enters the structure.
Instead of fighting heat after it gets inside, they prevent much of it from entering in the first place.
Turning Cracks into an Advantage
In traditional construction, cracks are considered a sign of damage and structural weakness. Builders usually try to prevent them at all costs.
The Penn researchers completely changed that perspective.
Rather than eliminating cracks, they designed them intentionally.
These microscopic cracks act like tiny water channels that pull water across the tile using capillary action, similar to how water travels through plant roots.
Instead of being a flaw, the cracks become an essential part of the cooling system.
How the Special Tiles Are Made
The tiles are produced using ordinary Portland cement mixed with diatomaceous earth (DE), a naturally porous material made from fossilized microscopic algae.
After the mixture is poured into thin tile molds, it is partially hydrated and then dried under carefully controlled conditions.
As the material shrinks during drying, stress develops inside it. Instead of forming random cracks, it creates a carefully designed network of predictable patterns.
This controlled cracking is the key innovation behind the technology.
Two Systems Working Together
The researchers discovered that storing water and moving water are two separate challenges.
The tiny pores inside the cement act like microscopic reservoirs, quickly absorbing incoming water droplets.
Meanwhile, the engineered cracks function like miniature canals, distributing water across the tile's surface.
This combination allows the tile to absorb water almost instantly—within milliseconds—before droplets can roll away.
Even on sloped walls, water spreads through the crack network instead of simply flowing downward.
The result is a surface that stays wet much longer, allowing evaporation to continue cooling the building for extended periods.
Cooling That Lasts for Hours
The researchers designed the tiles with a honeycomb-like hexagonal pattern.
Instead of allowing water to drain directly downward, the hexagonal geometry forces it to travel sideways through a zigzag network.
This greatly increases the amount of time water remains inside the tile.
Tests showed that the cooling effect can continue for up to 20 hours after watering.
This means a building could remain cooler throughout most of the day and even into the evening with relatively little water.
Easy to Produce and Affordable
One of the biggest advantages of this technology is its simplicity.
The tiles are made from inexpensive, widely available construction materials rather than rare or costly components.
The researchers also demonstrated that the cement mixture can be sprayed onto large building panels using standard hopper guns already common in construction.
This means the technology could be scaled up without requiring entirely new manufacturing systems, making it practical for widespread use.
Smarter Cooling in the Future
The team believes the next step is combining these cooling materials with smart automation.
Instead of watering buildings continuously, future systems could monitor weather forecasts, temperature and humidity in real time.
When hot conditions are expected, automated watering systems would provide just enough water to recharge the tiles.
This approach would maximize cooling while minimizing water consumption, making the technology even more sustainable.
A New Way to Design Climate-Friendly Buildings
As climate change increases the frequency of extreme heatwaves, architects and engineers are searching for ways to keep cities livable without dramatically increasing energy use.
The elephant-inspired cement tile offers a fresh approach by working with nature instead of against it.
Rather than sealing buildings off from the environment, these materials use one of nature's oldest cooling mechanisms—evaporation—to regulate temperature efficiently.
Sometimes, the best engineering ideas are hidden in the natural world. By transforming cracks from structural flaws into water-carrying cooling channels, Penn researchers have demonstrated that even the smallest design change can have a major impact. If adopted on a large scale, these elephant-inspired tiles could help create cooler buildings, lower energy costs, reduce carbon emissions and make cities more resilient in an increasingly warmer world.
Reference: , , , , , and , “ Elephant-Skin-Inspired Porous Cementitious Tiles with Programmable Crack Networks for Passive Cooling.” Advanced Materials (2026): e23133. https://doi.org/10.1002/adma.202523133
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