Saint Mary's University has a new living wall that uses leading-edge Canadian technology to purify the air by mimicking Mother Nature.

The wall at the Halifax university is composed of more than 1,000 plants. And unlike earlier living walls, it does more than pretty up the place.

The wall actually sucks the air through the wall and into the building's general ventilation system, said Dr. Alan Darlington, president of Ontario-based Nedlaw Living Walls, which built the Saint Mary's wall.

"We are looking at the living wall as more than just something that was aesthetic," said Darlington, a plant biologist. "We are looking at it as a piece of machinery."

It's a myth that plants clean the air simply because their leaves are exposed to it, he said.

"The purification is happening in the soil," he said. "The air has to get into the root zone, where the beneficial microbes break contaminants down."

Indoor living walls have been around for several years and in the early days were built as much for aesthetic reasons as for better air quality.

Nedlaw uses technology Darlington helped develop at the University of Guelph in the 1990s. He believes his is the only company in North America integrating living walls into ventilation systems.

At St. Mary's, about 19,000 cubic feet of air per minute goes through the wall.

Darlington said living walls have several benefits. They look nice and they remove contaminants that mechanical filters cannot.

Mechanical air-purifiers use carbon filters to remove contaminants such as dust, spores and chemicals, including benzene and formaldehyde, he said.

"However, the carbon filters act as a sponge and eventually fill up and become toxic," he added.

Living walls also save money on heating in the winter.

Air purification can sometimes account for up to 30 per cent of heating costs in the winter because new air brought into replace old air must be heated. Darlington estimated his living walls are 80 per cent more efficient in peak winter months because the same warm air is purified. New air from the outside is not needed.

"People like to have nature in their space and we can rationalize it for them very easily," he said.