Alcoa Develops Smog-Eating Panels to Keep Buildings Clean

Leveraging technology from the manufacturing firm Toto, Alcoa has added a special coating to its Reynobond architectural panels that works with the sun to neutralize pollution and dirt, enabling building facades to become self-cleaning.

Alcoa announced the product, called Reynobond with EcoClean, today and introduces it on Thursday at the American Institute of Architects' 2011 National Convention and Design Exposition in New Orleans.

The product is "the first coil-coated aluminum architectural panel that helps clean itself and the air around it," according to Alcoa Architectural Products and its president, Craig Belnap.

Alcoa first produced Reynobond architectural panels in 1989. The panels are made from large coils of painted aluminum that sandwich a continuous web of extruded polyethylene.

Known primarily in the U.S. for plumbing fixtures, ceramics manufacturing giant Toto, based in Japan, engineered its photocatalyst titanium dioxide technology called Hydrotect in 1998. The nontoxic substance produces a reaction between oxygen and humidity when exposed to natural or artificial ultraviolet light. The combination makes any surface to which the substance is applied hydrophilic, and  the water-loving surface repels dirt and oils. Toto has applied the substance to interior and exterior tiles and glass, and embedded it in paint. The firm says in a recent marketing video that Hydrotect is being used on more than 7,000 buildings around the world.

Using the technology as a jumping-off point, Alcoa has devised a way to apply a titanium dioxide coating it's calling EcoClean to the pre-painted aluminum surface of Reynobond panels. In sunlight, the panels effectively zap organic pollutants that would otherwise accumulate on the surface and the material, rendered harmless, is washed away by the rain. The panels also help cleanse the air around the surface. Here is a video showing how the Alcoa product works:

Belnap said the application of EcoClean adds two key benefits to Reynobond, whose appeal as an architectural panel includes the flexibility it offers as a lightweight product that can be used in new construction and retrofits.

The new panels help property owners and operators save the maintenance costs for detergents, water and labor to wash buildings. With structures that would otherwise be washed several times a year, "we anticipate only a need to spray down the building every three to five years," Belnap said.

The second benefit, though difficult to quantify, can be as powerful as bottom-line savings to firms that are highly brand sensitive on issues involving the environment and sustainability, said Belnap. The product reduces dirt- and pollutant-laden runoff from building surfaces and cuts water use for exterior maintence. Ten-thousand square feet of Reynobond with EcoClean provides the equivalent air-cleaning effect of 80 trees, Alcoa estimates -- a benefit the company's European operations plan to emphasize in a marketing tagline that runs, "With Reynobond and EcoClean, how much forest can I build?"

The material has further environmental attributes that can contribute to green building certification programs. The aluminum in Reynobond is 90 percent recycled content and overall the product is 45 percent recycled content by weight, Belnap noted.

Alcoa's explorations with titanium dioxide coating were prompted by service station customers who were seeking ways to keep their buildings -- subjected to the grime created by vehicle exhaust in high-traffic areas -- clean, highly visible and easily recognizable from a distance, said Belnap. The first field test of the product was conducted in 2009 and "we were stunned by the results," he said. "They were remarkable."

Two pilot projects involving Reynobond panels with EcoClean are underway in North America and Europe, both of them by LEED users, Belnap said. The work in North America is an architectural project, and in Europe the product will be used at several locations of a retail chain, he said. Alcoa anticipates the product will be particularly attractive to restaurants, retailers, hotels and other firms that want their buildings to have a "strong, bright image ... and reinforce the concept of sustainability," Belnap said.

In addition to the self-cleaning building materials manufactured by Alcoa and Toto, photocatalytic products on the market include MonierLifetile's Smog-Eating Tiles for residential and commercial roofs. MonierLifefile is a company of Boral Roofing, which is a division of Boral USA, based in Roswell, Ga.

Images courtesy of Alcoa.