TU Graz Cools Rooms With 3D-Printed Ceramic Cubes and Zero Electricity

Researchers at Graz University of Technology have built a passive cooling wall from 3D-printed ceramic cubes that needs no power to run. In a hot attic test, a water-filled cube lowered the air temperature nearby by almost 7 degrees Celsius. The idea is simple, but the geometry is not.

Each cube measures about 23 centimeters along each side and is printed from a clay mixture, then fired at low temperature to keep it porous. Inside, a triply periodic minimal surface creates a maze of channels with a huge surface area packed into a small volume. Water is drawn in by capillary action and spreads through the structure. As it evaporates, it pulls heat out of the surrounding air.

People have used the same physical principle for centuries in clay water jugs and wind towers. The difference here is that 3D printing lets the team shape pores and passages that would be impossible to mold by hand. Milena Stavric, associate professor at TU Graz's Institute of Architecture and Media, said the printed structures store water efficiently and create an enormous evaporation surface despite their compact size.

The group is also testing bio-inspired recipes in its Shape Lab. Fungal cultures and sawdust are mixed into the clay; the mycelium grows through the mixture before firing, and the organic material burns away, leaving extra micro and macro pores that help water move through the ceramic.

A 2-by-2-meter demonstration wall is now standing on the university's Neue Technik campus in Graz. The team says the technology could cool indoor spaces, schools, offices, and public waiting areas without adding to the grid load on hot days. In cities where trees cannot provide enough shade, walls like this could offer a low-energy alternative to air conditioning.