First in Their Class: Innovative Design Solutions for Schools of the Future
Roofs: Transforming Outdoor Air
For centuries, architects have chosen tile roofs for aesthetics and durability. Today, with catalytic coatings, tile roofs can also enhance air quality. Photo courtesy of Boral Roofing |
The development of photocatalytic coatings on tile and concrete roofs has delivered on the vision of self-cleaning buildings. This catalytic process was first introduced in Europe for road construction and medical facilities, and is now available in North America. These new roof tiles tend to promote a cleaner environment while turning "waste into food."5 One of the oldest roofing systems, concrete tiles, has new properties that make them able to mitigate air pollution. They can now be coated with a specially prepared catalyst that is embedded in the upper portion of the tile body. When exposed to sunlight, this catalyst speeds up the oxidation process, thereby resulting in the reduction of the formation of air pollution. Additionally this unique function destroys organic substances that come in contact with the tile surface such as mold, algae and moss.
The upper portions of the tiles are coated with a mineral crystal substance, similar to those used in toothpaste or sunscreen. When exposed to sunlight, this catalyst speeds up oxidization, and converts nitrogen oxide that is in the air from automobile pollution, into nitrogen. Working much like a catalytic converter does in a car, this roofing system transforms harmful substances into safe ones. The dirt, algae and moss neutralized by contact with the roof surface can be easily washed off the roof surface to fertilize the plants below.
Air pollution is an undisputed problem and the World Health Organization estimates 2.4 million people die annually of causes attributable to air pollution. Manufacturers estimate that 2,000 square feet of treated roofing tile can mitigate the same percentage of nitrogen oxide (a major component of smog) produced by one car driven just over 10,000 miles. Airborne pollutants are destroyed by the effect of sunlight on the catalyst and are rinsed off by rainfall or a garden hose. A study by the Fraunhofer Institute6 showed a significant decrease in air pollution when tiles were exposed to UV lighting. An additional benefit of a treated concrete tile is when installed on the roof it reabsorbs up to 20 percent of carbon dioxide emissions created during its manufacturing process.
Both concrete and clay roof tiles are made from materials with an inorganic surface and recycled content that withstand the harshest wind and weather conditions. They are durable and often are considered the most practical choice when calculating the lifecycle effectiveness of a construction material. Used on a school roofing system, they will reduce maintenance, as well as lower its smog footprint.