Zurich team develop wall tiles to passively control humidity

A team of researchers from ETH Zurich have developed an alternative to the mechanical dehumidifying of spaces in which large numbers of people typically gather. 

Recognising that the use of traditional ventilation systems to reduce humidity in spaces such as offices and exhibition rooms costs energy and is potentially damaging in climate terms, the team investigated a new, passive approach to  dehumidification in which moisture is temporarily stored in the walls and ceiling of the room.

The report summarises the development thus: ‘The unprecedented moisture buffering ability of the components developed in this study enables a paradigm shift in how we approach the challenge of indoor hygrometric comfort, moving away from a predominant reliance on mechanical systems towards more passive, material-driven solutions.

‘This technology can play a key role in spaces where the installation or use of mechanical systems is restricted, for example, in buildings protected by preservation mandates or in areas subjected to energy precarity.’

The hygroscopic, moisture-binding material they turned to was created from finely ground waste from marble quarries.

This powder was chemically bound into a composite mixture consisting of aqueous potassium silicate solution (29%), metakaolin (14%), and aggregates (57%).

The team used advanced 3D printing to produce a prototype of a wall and ceiling component measuring 20 × 20cm and 4cm thick. They observed that ‘the synergy of the superghyroscopic nature of the material and the efficient geometric design of the 3D-printed components led to remarkably high humidity-regulation performance with reduced material usage.’

Benjamin Dillenburger, Professor for Digital Building Technologies explains: ‘This process enables the efficient production of components in a wide variety of shapes.’

Building physicist Magda Posani led the study of the material’s hygroscopic properties at ETH Zurich. A simulation was set up of a reading room used by 15 people in a public library in Portugal which had been completely lined with the tiles.

Posani calculated how often and to what extent the humidity exceeded the comfort zone, (40% to 60% relative humidity) over the course of a year and calculated a discomfort index.

It was found that if the reading room were fitted with the moisture-binding components, the discomfort index could be reduced by 75% compared to a conventional painted wall. If the tiles were just 1cm thicker, the discomfort index fell by as much as 85%.

Posani said: ‘We were able to demonstrate with numerical simulations that the building components can significantly reduce humidity in heavily used indoor spaces.’

Guillaume Habert, Professor for Sustainable Construction, who supervised the ETH research project said: ‘Our solution is suitable for high-traffic spaces for which the ventilation systems already in place are insufficient.’

The intention now is to scale the process for industrial manufacture while continuing to work developing components with even lower greenhouse gas emissions.

The full research can be read here.