TU Graz Tests 3D-Printed Cooling Walls That Need No Power

Passive cooling, 3D printed

Europe is sweating through another brutal heatwave. Temperatures across Austria, France, Italy, and Spain have topped 40C this month. In cities, the heat feels even worse because concrete and asphalt trap warmth.

A team at the Institute of Architecture and Media at TU Graz thinks 3D printing can help. They built cooling cubes from ceramic clay that lower nearby air temperature by almost 7C. No electricity required.

How the cubes work

The principle is simple. Water draws heat from its surroundings as it evaporates. People have used this effect for centuries in clay jugs and wind towers. The TU Graz team updated the idea with 3D printing.

Each cube measures about 23cm across. The printer lays down a ceramic clay mixture with precise internal channels. After firing, the result is a highly porous structure that soaks up water through capillary action. The water spreads across a massive internal surface area and evaporates steadily, pulling heat from the air.

"The key technological advance here lies in the use of 3D printing, which enables us to produce highly complex, porous and functionally optimised geometries from clay mixtures," said Milena Stavric from TU Graz.

Mycelium and sawdust boost performance

The researchers are testing an upgraded version. They mix fungal cultures and sawdust into the clay before printing. The mycelium grows through the material. During firing, the fungus and sawdust burn away, leaving a network of micro and macropores. Those extra channels let water move through the cube even faster.

The team is also experimenting with dredged sediment from Lake Neusiedl. The lake needs regular dredging to prevent silting, so the sediment is a waste product. Turning it into a 3D-printable building material kills two birds with one stone.

Real-world test results

The team installed a 2x2 meter demonstration wall on the TU Graz campus. A water-filled cube dropped the local temperature by nearly 7C in a hot attic test. Kristijan Ristoski, who wrote his Master's thesis on the integration, said the cooling effect was clearly noticeable throughout the room.

A display at the Museum of Perception in Graz lets the public see the technology. The research team, funded by Austria Wirtschaftsservice GmbH, is now open to inquiries from architects and builders.

The pitch

The cubes are not meant to replace air conditioning in every situation. They are an alternative for homes, offices, schools, and public spaces where trees cannot provide enough shade. The goal is to deliver cooling without the energy bill or the carbon footprint.

As heatwaves become more common, low-tech solutions like this deserve attention. 3D printing gave the researchers a way to optimise geometry in ways traditional manufacturing cannot match. The result is a passive cooling system that runs on water and evaporation alone.