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The Toronto Regional Conservation Authority installed a two-sided Nedlaw Living Wall Biofilter.

Alan Darlington once worked on research at the University of Guelph that used plants to produce fresh air on spacecraft, with the goal of enabling manned, long-distance space missions.

His project turned into an innovative business opportunity with applications on Earth – and it transformed Dr. Darlington into a chief executive officer.

At the centre of his research and business, Nedlaw Living Walls Inc., is the ability of plants and the microorganisms that live on their roots to filter pollutants out of stale air, providing fresh air that is healthy and pleasant for humans.

Nedlaw designs, manufactures and installs green biowalls that purify air for buildings. Since its start more than 10 years ago, about the same time as the U.S. Environmental Protection Agency identified indoor air quality as one of the top five threats to human health, Nedlaw has become the leading supplier of living biowalls, said Dr. Darlington, who is the company's founder and president.

"The amazing thing about nature is that it has this unique ability to repair itself," said Dr. Darlington, whose PhD is in controlled environmental systems, the study of sustaining life in a closed space such as a spacecraft or submarine.

Nedlaw's walls rely on microorganisms living on the roots of plants that remove volatile organic compounds and formaldehyde, which are harmful to human health, from circulating air.

Last year, Nedlaw installed the largest living wall that it knows of in the United States, a 1,570-square-foot, five-storey wall in the Papadakis Integrated Science Building at Drexel University in Philadelphia.

"We're getting rid of 60 to 70 per cent of the pollutants in the air after a single pass through the filtration system," Dr. Darlington said. "It means less fresh outdoor air has to be brought in to maintain air quality and that significantly reduces the energy required to heat or cool that air. It's a really beautiful technology."

Donald Schmitt, a principal at Diamond Schmitt Architects in Toronto, which designed the Drexel building, learned of Dr. Darlington's research when he was designing the University of Guelph's Humber campus building almost 10 years ago. Dr. Darlington taught at Guelph and the university wanted to showcase his innovative application by featuring a living wall.

Nedlaw is a small private company, based in Breslau, Ont., west of Guelph, with about 20 employees who design, build, install and maintain biofilter walls. Dr. Darlington declined to give revenue figures.

Its living wall system is integrated into a building's air circulation system. Although existing buildings can be retrofitted with living walls, new buildings usually operate more efficiently and deliver the greatest savings and benefits.

The wall itself is housed in an open case covered by a plastic Brillo pad-like surface into which plants' bare roots are inserted into pockets. Rainwater is recycled from a roof catchment and runs down the wall, providing the nutrients the plants need to thrive.

Although some customers say their walls require continuing attention, Dr. Darlington maintains that all the walls Nedlaw has installed are operating with just the basic maintenance the company provides.

"I'd say the main challenge is making sure the plants get the right lighting to grow," he said. "But in new buildings that are designed to support walls, they're easy to manage."

Unlike conventional green walls, in a living biowall the plants' bare roots are exposed to the air that's pulled through the wall. Microbes on the roots ingest pollutants in the air. The plants themselves also produce small amounts of oxygen but not in large enough quantities to contribute significantly to air quality, Dr. Darlington said.

Recent research by the University of Guelph on a dozen of Nedlaw's installed walls shows that, on average, they produce up to 100 litres of virtual outside air per square metre of wall per second.

"Those are great results and we're very proud that we can quantify the benefits that come from real-world biofiltration," Dr. Darlington said.

The company's first wall began operating in 2004, and it now has about 200 in Canada and the United States.

"As more buildings open with the walls, we get more interest from the area around those buildings," he said. "There's also a certain cachet now for those buildings that have a wall, so we're trying to step up our marketing. Drexel has sowed the seeds for us in the U.S."

Inquiries are beginning to come from Europe, too, and Nedlaw is also developing a biofiltration system that can be used in private residences.

Dr. Darlington intends to press ahead with expansion while patent protection is in place.

"Intellectual property is a whole other issue," he said. "We have patents issued in 2003. But they don't actually provide protection for that long so we want to move quickly. But patents are just one of the tools we have."

Marketing is one of Nedlaw's top priorities now, he said. "And one of the best marketing tools we have is having people see one of our projects."

Until now, the distinctive green walls and the noticeably fresh air they create while saving energy have largely sold themselves.

The next test will be whether a talent for innovative science will translate into marketing savvy.

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