In Cairo, an annual temperature inversion brings a fog of dust and burning biomass called the Black Cloud. When Carmen Trudell began researching the city’s air quality problems five years ago, she thought about her brother’s treatment for kidney failure: What if a building, like the organ, could filter toxins and protect people?
Since then, Trudell, now at the firm Both Landscape and Architecture, in Charlottesville, Va., and an assistant professor of architecture at California Polytechnic State University, San Luis Obispo (Cal Poly), worked with students and fellow environmental engineering associate professor Tracy Thatcher to develop a building component that could double as a passive filtration system. The product would be easy to construct and work without electricity to allow its use in developing countries.
Inspired by vacuum cleaners that spin air through a vortex to separate particles, the team “came up with the idea of putting a cyclone inside of the exterior wall,” Trudell says. They developed the Breathe Brick, a porous concrete masonry unit that stacks to form an air-filtration and structural façade system.
The faceted surface of the bricks helps direct outside air to
rectangular inlet ports. A cyclone filter cast directly into the concrete form causes the incoming air to spin, winnowing out particulates. Brick couplers made from recycled
plastic help align the stacking modules’ two vertical shafts—one to accommodate
structure reinforcement, and one to send the distilled particulates into a collection
hopper at the wall base. The filtered air that passes into the cavity of the double-wythe wall system could then supply an HVAC system or an adjacent interior space directly.
The jury appreciated the relatively inexpensive, low-tech solution to a worldwide problem. “Breathe Brick is a clever way of taking the heavy particulates out of the air as a byproduct of making a building,” said juror Steven Rainville.
But the jury also wondered about the practical implications of, as Joyce Hwang put it, “having thousands of Britas in your house.” To which Trudell says that the collection hoppers, which span multiple brick lengths, would need to be cleaned regularly, but not frequently.
To test the Breathe Brick concept, Cal Poly engineering students
constructed a small-scale wind tunnel, 2 feet in diameter and 12 feet long,
into which they blasted cornstarch and flour against four prototype modules.
The units captured 30 percent of fine particles—which are defined by the
Environmental Protection Agency as having a diameter of 2.5 microns or smaller,
and found in smoke and haze—and as much as 100 percent of coarse particles, which
measure 10 microns and larger and simulate dust. The next step
for Trudell and her team is to test the Breathe Bricks’ performance in a
Funding: Cal Poly College of Architecture and Environmental Design's Planning, Design and Construction Institute