Bio-Inspired Cement Tiles Cool Buildings Through Evaporation

Researchers at the University of Pennsylvania have developed a cement-based tile that passively cools building surfaces by capturing and gradually evaporating water. Inspired by the cracked skin of African elephants, the material could help architects reduce dependence on energy-intensive air conditioning in increasingly hot urban environments.

Learning From Elephant Skin

African elephants cannot sweat, but networks of wrinkles and cracks in their skin retain water after bathing or spraying. As this trapped moisture slowly evaporates, it removes heat from the animal’s body.

Architect Dorit Aviv of the Weitzman School of Design and materials scientist Shu Yang of Penn Engineering translated this natural cooling mechanism into a façade material. Their design combines ordinary Portland cement with diatomaceous earth, a porous material derived from fossilised algae.

Engineered Cracks Become Cooling Channels

Cracks are normally considered a sign of deterioration in construction materials. In this case, however, they are deliberately engineered to create a functional network of microscopic channels.

During production, thin tiles are partially hydrated and dried under controlled conditions. Shrinkage generates a predictable honeycomb-like pattern of cracks rather than random fractures. Microscopic pores within the material rapidly absorb water, while the cracks distribute it across the surface. The geometry directs water laterally and can even transport it against gravity on inclined surfaces.

By keeping the tile wet for longer, the system supports evaporative cooling for up to 20 hours. Water is absorbed within milliseconds, limiting the bouncing, beading and rapid run-off commonly seen on conventional building surfaces.

Lower Temperatures Without Mechanical Cooling

During tests using infrared heating and periodic watering, the temperature beneath the experimental tiles remained stable at 89.6°F (32°C). Cracked commercial stucco reached 107.6°F (42°C), while uncracked stucco rose to 125.6°F (52°C). According to the researchers, the bio-inspired surface could remain approximately 10–20°F (6–11°C) cooler than conventional stucco.

Unlike mechanical air conditioning, the passive system requires no fans, compressors or moving components. It also avoids transferring indoor heat directly into the surrounding urban environment. However, its broader environmental performance will depend on factors including water availability, cement-related emissions, durability and maintenance.

Towards Scalable Cooling Façades

The diatomaceous earth and cement mixture can be sprayed onto large panels using hopper guns, offering a potentially affordable route to on-site production. Future versions could incorporate automated watering controlled by weather forecasts, supplying only the amount needed under specific conditions.

The researchers are now exploring commercial applications through Minerava, a venture focused on carbon-capturing, passive-cooling concrete for infrastructure.

Source & photos: University of Pennsylvania