3D-Printed Ceramic Cooling Walls Fight Urban Heat at TU Graz

A research team at Graz University of Technology has built a cooling wall that needs no power, no refrigerant, and no electronics. It works because water evaporates through 3D-printed ceramic cubes.

The cubes measure roughly 23 centimeters on each side. They are printed from a ceramic clay mixture using a minimal-surface geometry that creates an enormous evaporation surface while using very little material. After printing, the cubes are fired at low temperatures so they stay highly porous. Water climbs into the pores by capillary action and spreads evenly across the complex internal structure. As it evaporates, it pulls heat from the surrounding air.

In a hot attic test at TU Graz, a single water-filled cube produced a measured temperature drop of almost 7C nearby. The team says the effect was felt throughout the room. A free-standing two-by-two-meter demonstration wall is now installed on the university campus, and a second display sits at Graz's Museum of Perception.

The project is funded by Austria Wirtschaftsservice GmbH and carried out with TU Graz's Institute of Building Physics, Services and Construction. The team is also testing bio-inspired material blends, including fungal mycelium and sawdust mixed into the clay, which burn away during firing to leave additional micro-pores. Lake Neusiedl sediment, a local dredging byproduct, is another candidate material.

The aim is practical, not experimental. Cities hit by heat islands often cannot plant enough trees to bring temperatures down. These ceramic walls offer an alternative to air conditioning in schools, waiting areas, and residential buildings where electricity demand is a concern.