In contemporary architecture, the need for more sustainable cities is driving innovative solutions such as Breathe Bricks. The concept was developed in 2015 by Professor Carmen Trudell at Cal Poly in the United States. The technology turns a building’s external walls into a passive air-filtration system, helping to improve the quality of the air entering the building.
The basic idea was inspired by the cyclone separation process used in vacuum cleaners. Each concrete brick is hollow and has a specially shaped outer surface that directs air into its interior. As polluted air enters the brick, it is forced into a strong swirling motion. Centrifugal force separates heavier pollutant particles and dust from the air, causing them to lose momentum and fall towards the base of the wall, where they are collected in a dedicated compartment. The filtered air is then directed into the building.
The system works as a double-wall structure. The outer layer is made up of Breathe Bricks, connected by specially designed fittings made from recycled plastic to ensure stability and maintain the correct airflow. Behind this sits a ventilation cavity, followed by a conventional inner wall that provides the necessary insulation.
Laboratory tests to date have shown promising results. The system can capture 100% of coarse particles, such as sand, and 30% of fine airborne PM10 particles. One of its main advantages is that the filtration process requires no additional energy, relying entirely on the pressure of the wind.
There are, however, some challenges. Introducing outside air into the wall structure can affect a building’s thermal insulation, making enhanced internal insulation necessary. The system may also become less effective in very tall buildings because of variations in wind conditions, while producing these bricks takes longer than manufacturing conventional ones.
Despite these limitations, Breathe Bricks demonstrate how future building materials could combine construction with environmental benefits. German researchers have already explored a further development of the concept through so-called ‘Living Bricks’, made with bioactive enzymes and limestone. Rather than simply filtering dust, these materials are designed to chemically bind carbon dioxide and nitrogen oxides, converting them into less harmful substances and, in this sense, performing a role similar to that of trees.
