Europe is living through its fourth major heatwave of the 2026 season, with temperatures above 40°C recorded across the Iberian Peninsula, France, Italy, and Austria. Cities are hit hardest: urban heat island effects can push local temperatures 1.7 to 4°C or more above surrounding rural areas. Against that backdrop, the Institute of Architecture and Media at TU Graz is testing a low-tech physical principle to cool buildings without drawing power. They’re leverage the power of evaporative cooling, delivered through 3D-printed, highly porous ceramic cubes. Another testament to how 3D printing can be used to create sustainable technology.
An up-close look at the 3D printed cubes.
What Is Evaporative Cooling?
When water evaporates, it draws heat from its surroundings, causing evaporative cooling. “[Evaporative cooling] has been working for centuries, both in clay jugs and in traditional wind towers,” explains Milena Stavric from TU Graz. “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. These special structures store water particularly efficiently and, despite their small volume, create an enormous evaporation surface.”
The cubes, with sides of around 23 centimetres, are 3D printed from a ceramic clay mixture, then fired at low temperature to reach a highly porous consistency. Water is drawn into the porous ceramic by capillary forces and spreads evenly through the structure, creating a large surface over which it continuously evaporates, pulling heat from the surrounding air.
3D Printed Cooling Walls: Made with Fungus
To push cooling performance further, the team is testing a bio-inspired variant developed in the institute’s Shape Lab. Fungal cultures and sawdust are added to the clay as a nutrient medium; a mycelium, the thread-like network of fungal filaments, grows into the material before it is printed and fired. The mycelium and sawdust burn away during firing, leaving behind a network of micro- and macro-pores that lets water spread even more effectively through the cube.
TU Graz is also testing dredged sediment from Lake Neusiedl, a shallow lake that requires regular dredging to slow silting, as another 3D-printable, resource-efficient building material currently disposed of without reuse.
From left to right: Julian Jauk, Milena Stavric and Kristijan Ristoski from the Institute of Architecture and Media at Graz University of Technology.
Tested with a Demonstration Wall
The team tested the effect in a hot attic at TU Graz. A water-filled cube produced a measured temperature drop of almost seven degrees Celsius in its immediate vicinity. “The cooling effect was clearly noticeable throughout the room,” says Kristijan Ristoski, who wrote his Master’s thesis on integrating the cubes and water supply into the cooling wall.
A free-standing, two-by-two-metre demonstration wall is now installed at TU Graz’s Campus Neue Technik in Stremayrgasse, Graz, alongside a display at the city’s Museum of Perception. The research team, working with TU Graz’s Institute of Building Physics, Services and Construction and funded by Austria Wirtschaftsservice GmbH (aws), says it is open to contact from planners and companies evaluating the technology.
Milena Stavric from the Institute of Architecture and Media at TU Graz with a cooling cube.
The team positions the cubes as an alternative to energy-intensive cooling systems for homes, offices, schools, and public spaces, especially where trees can’t provide enough shade. “Our aim is to provide cooling where people suffer particularly from the heat – for example, in cities where trees are sometimes unable to provide sufficient cooling. To achieve this, we rely on natural cooling principles rather than energy-intensive air-conditioning technology,” says Milena Stavric.
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*All Photo Credits: Lunghammer – TU Graz