Researchers develop moisture-storing materials for buildings

Utilising a sustainable approach

A team of researchers at ETH Zurich has developed a revolutionary, climate-friendly building material that reduces indoor humidity, creating a more comfortable environment in high-traffic indoor spaces. The new technology utilises a sustainable approach to moisture control, replacing energy-hungry ventilation systems with an innovative passive solution.

The material, designed for walls and ceilings, binds and temporarily stores excess moisture in spaces like office meeting rooms, exhibition halls, and waiting areas. Due to the large number of occupants, these environments are often subject to fluctuating humidity levels and typically rely on mechanical systems to regulate indoor air quality.

However, while effective, mechanical dehumidification systems consume significant energy and contribute to carbon emissions, mainly depending on the source of electricity. The ETH Zurich team’s innovation offers a greener alternative in this case.

The new material is described as “passive” because it absorbs moisture from the air and stores it in the building’s walls and ceilings. Unlike mechanical ventilation, which expels moisture into the external environment, this innovative material holds and releases moisture when the room is ventilated.

Professor Guillaume Habert, who supervised the research, says the solution especially benefits spaces with insufficient existing ventilation systems.

“Our solution is suitable for high-traffic spaces where traditional ventilation systems cannot keep up with moisture levels,” said Habert, Professor of Sustainable Construction at ETH Zurich.

The researchers developed the material following the principles of circular economy, selecting waste from marble quarries as the primary ingredient. The finely ground marble waste is mixed with a geopolymer binder from metakaolin (often used in porcelain production) and an alkaline solution.

This combination transforms the marble powder into a moisture-binding building material. Unlike cement, the geopolymer binder used in this process emits significantly less carbon dioxide during production, making it an environmentally friendly alternative.

3D printing technology

ETH Zurich researchers created the building components using cutting-edge 3D printing technology. Using a binder jet printing technique, they produced prototypes of wall and ceiling elements measuring 20x20cm and 4cm thick. The process involves layering marble powder and binding it with geopolymer, allowing for the highly efficient production of custom-shaped components.

Professor Benjamin Dillenburger, who led the project’s 3D printing, highlighted the approach’s advantages. This process enables the production of components in a wide range of shapes, offering design flexibility and efficiency,” Dillenburger explained.

This flexibility is crucial in creating components that fit various architectural styles while maintaining their moisture-controlling capabilities.

Beyond its environmental benefits, the new material enhances comfort in indoor spaces. Stabilising humidity levels reduce the discomfort often accompanying high moisture levels, such as sticky air or surface fogging. This passive method of humidity control is not only energy-efficient but also contributes to a healthier indoor climate.

The research, led by building physicist Magda Posani, has shown promising results in improving the material’s hygroscopic properties. Posani, who recently moved to Aalto University in Espoo, Finland, was crucial in studying how the material reacts to varying humidity levels.

Her research on the moisture-absorbing properties laid the foundation for this breakthrough in sustainable construction. The project also benefitted from the expertise of materials scientist Vera Voney and architect Pietro Odaglia, who helped develop the material and 3D printing techniques at ETH Zurich.

This sustainable building component offers an exciting opportunity to reduce buildings’ carbon footprints. As more attention is directed toward sustainable construction practices, solutions like this could significantly reduce the need for energy-intensive mechanical systems, ultimately making buildings more eco-friendly and comfortable.

ETH Zurich’s groundbreaking research exemplifies the potential of combining digital technologies, such as 3D printing, with sustainable material science. As demand for green buildings grows, innovations like these will likely become key components of future architecture.

Image: The new material is described as “passive” because it absorbs moisture from the air and stores it in the building’s walls and ceilings. Credit: Lisa Fotios