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Researchers at the University of Pennsylvania have developed a porous cementitious tile that mimics the natural cooling mechanism of African elephants, offering a passive way to lower building temperatures without high energy consumption. According to a study published in Advanced Materials by researchers at Penn Engineering, the tiles utilize programmable crack networks and diatomaceous earth to store and evaporate water continuously.
How Elephant Skin Inspired Passive Building Cooling
African elephants regulate their body temperature using their thick, cracked skin to store water gathered during bathing, which slowly evaporates to create cooling relief over extended periods. To replicate this “cooling without sweating” process on building facades, the Penn Engineering research team needed to solve a basic engineering hurdle: standard construction materials shed rainwater rather than absorbing it. According to the study “Elephant-Skin-Inspired Porous Cementitious Tiles with Programmable Crack Networks for Passive Cooling,” the team mixed ordinary Portland cement with diatomaceous earth—a soft sediment composed of fossilized diatom shells—to cast thin plates. By controlling drying conditions, the team induced specific material stresses that formed a deliberate network of tiny channels rather than random fractures.
Water Retention and Anti-Gravity Evaporation Mechanics
The engineered tiles feature a hexagonal honeycomb geometry that forces absorbed moisture to move in a zigzag, sideways pattern across the surface rather than simply pooling downward due to gravity. According to the Penn Engineering researchers, this capillary network allows the tiles to retain and evenly distribute water even when mounted on angled exterior walls. Laboratory testing demonstrated that the tiles maintain a consistent cooling effect for up to 20 hours following hydration.
Experimental Results and Energy Savings
In experimental evaluations under continuous infrared irradiation and regular watering, the temperature beneath the porous tiles remained steady at 32 degrees Celsius. By comparison, surfaces covered with standard building plaster reached 42 degrees Celsius under identical exposure, while crack-free plaster recorded 52 degrees Celsius. The research team projects that outfitting buildings with these cement tiles can lower indoor temperatures by 6 to 11 degrees Celsius compared to conventional exterior finishes. To minimize water consumption in practical applications, the researchers suggest pairing the panels with smart irrigation systems driven by real-time weather data to hydrate building exteriors only during designated dry cycles.
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