‘Smog-eating’ building tiles use titanium dioxide and silver that degrades in air, humidity and light to reduce hazardous pollutants
Air pollution is responsible for 7 million premature deaths worldwide each year and new evidence that long-term exposure may also increase the risk of death from Covid-19 should drive interest in ‘smog eating’ building materials and treatments.
Most of these technologies exploit the process of photocatalysis, using chemicals and sunlight to break down dirty air, but active ceramics, developed by Fiandre Architectural Surfaces and the University of Milan, are modified to remain effective even under artificial light, as well as fight bacteria and viruses.
Active ceramic surfaces combine titanium dioxide and silver. When air, humidity and light are present, they become oxidized, degrading hazardous pollutants that come into contact, such as nitrogen oxides (NOx) and volatile organic compounds. When used on facades, harmful molecules are neutralised before they can penetrate windows or air conditioning intakes.
The tiles are proven to be effective under UV, solar or LED lights and the combination of oxidization and silver makes them resistant to viruses and bacteria, including MRSA, which is particularly dangerous to humans. The jury is still out on their efficacy against coronavirus.
A key testbed for the technology was the De Castillia 23 sustainable building complex in Milan, designed by Italian architect Progetto CMR.
Around 16,000m2 of tiles from Fiandre’s Core Shade collection, including Cloudy Core Active and Sharp Core Active textures, was custom-developed and installed on external ventilated facades, balconies and floors in outdoor areas.
Together they neutralise about 59kg of NOx per year, equivalent to over 200,000m2 of green space, according to estimates by the Chemistry Department at the University of Milan.
An additional benefit is that tiles are easier to clean, using only water and mild detergents instead of toxic or expensive chemicals, because rain and dirt are less likely to adhere to them than to traditional tiles.
The approach enables a high degree of design freedom, said Stefano Finazzi, senior architect at Progetto CMR: ‘The big advantage of this chemical treatment, compared to other systems, is it can be applied to any possible finish without constraints. Its effectiveness is not affected by colour, roughness, size or any other visible features of the material onto which it is applied.’
He added: ‘There is no visible difference between a standard tile and an active tile. The additional costs are reasonable too, so this choice appears as a good combination of architecture and sustainability.’