Researchers have developed cement-based tiles inspired by the cracked, water-retaining skin of African elephants that could help cool buildings through slow evaporation, reducing reliance on mechanical air conditioning.
The tiles combine microscopic pores with deliberately engineered cracks that capture water, redistribute it across the surface and allow it to evaporate gradually. In building-scale experiments, temperatures beneath the new tiles remained around 89.6°F, compared with 107.6°F beneath cracked commercial stucco and 125.6°F beneath conventional, non-cracked stucco.
The research led by architect Dorit Aviv and materials scientist Shu Yang with collaborators at the University of Pennsylvania and Syracuse University, reimagines cracks normally regarded as a sign of material failure as functional pathways for water movement and thermal management.
How Elephant Skin Inspired the Design
African elephants live in intense heat despite having thick, dark skin and lacking the ability to cool themselves through sweating. Their skin contains a network of wrinkles and cracks that can retain water after they spray themselves. The trapped moisture evaporates slowly, removing heat from the body.
Researchers sought to apply the same principle to buildings.
The resulting tiles use ordinary Portland cement combined with diatomaceous earth, a porous material derived from fossilised algae. The combination creates a surface capable of rapidly absorbing water while engineered cracks distribute the moisture across the tile.
The microscopic pores act as small reservoirs, while the larger crack network functions like a system of channels that transports water across the surface.
Turning Cracks Into Cooling Channels
The researchers deliberately controlled how cracks formed as the cement based material dried and shrank. Instead of allowing random fractures to develop, they guided the stresses along predetermined patterns.
Several designs were tested, including triangular, square and hexagonal arrangements. The hexagonal pattern performed particularly well because its geometry encouraged water to move sideways in a zigzag path slowing drainage and increasing the time available for evaporation.
The material absorbed individual water droplets in less than 50 milliseconds. Once inside the tile water travelled through the engineered crack network and remained available for evaporation for extended periods.
In some experiments, the cooling effect lasted as long as 20 hours.
Significant Temperature Reduction
The researchers tested the tiles using infrared heating and periodic watering. The elephant skin inspired surface kept the temperature beneath it at approximately 89.6°F.
By comparison, the temperature beneath cracked commercial stucco reached about 107.6°F, while non cracked stucco reached 125.6°F.
Tests on a small model building also showed that the new tiles could distribute and retain water more effectively than conventional stucco when both received similar amounts of water.
The findings suggest that controlling how water is captured and transported across a building surface can substantially improve evaporative cooling.
Potential for Energy Efficient Buildings
Unlike conventional air conditioning systems, the technology does not require compressors, fans or other moving mechanical components. It relies on passive processes involving water absorption, distribution and evaporation.
The researchers demonstrated that the material could also be applied to larger panels using hopper guns, indicating potential for construction scale applications.
Future versions could incorporate automated watering systems controlled by sensors and weather forecasts. Such systems could deliver water only when cooling is required, potentially reducing unnecessary water consumption.
The approach could be particularly useful in hot, dry regions, where evaporative cooling can be highly effective.
A Complement to Air Conditioning
The researchers emphasise that the technology is not intended to completely replace air conditioning, particularly during periods of dangerous extreme heat. Instead, cooler roofs and façades could reduce the amount of heat entering buildings and lower the workload placed on mechanical cooling systems.
As global temperatures rise and heat waves become more frequent, passive cooling strategies could become increasingly important for homes, schools, workplaces and other buildings.
The study demonstrates how biological adaptations can inspire new approaches to climate resilient architecture. By using naturally occurring processes rather than relying entirely on mechanical systems, materials such as these tiles could contribute to cooler, more energy efficient and more climate adaptive buildings.