With Chicago laying claim to having the most “green” roofs of any city in North America, it stands to reason that the next building section that will be getting some notoriety in this part of the country will be the “green” wall.

Rooftop decks, gardens and vegetation account for about 7 million square feet of green space in the city of Chicago, with the city government setting an example with a rooftop garden atop the City Hall building.

The city has burst into the global spotlight in this environmental push since Mayor Richard Daley became a major booster after he learned about green-roof construction and design during a visit to Hamburg, Germany in 1997.

Still, there remains debate about whether Chicago has really forged ahead in this area, or if the movement remains in an early stage, with future design and benefits still being tapped.

Regardless of the environmental benefits – and there are many with energy savings, pollution control and natural noise buffers – the dawn of the green rooftop era appears to have descended into the green wall era.

The creation of a “living wall” within a structure may become more prevalent, with a current example unfolding at the Greenbelt Cultural Center under construction in North Chicago by the Lake County Forest Preserve.

The green wall being considered would be the first of its kind in the United States to use plants to filter and clean indoor air.

Proponents of the green wall project say it is much more than just a wall with plants. They view it as a key component of a building’s entire air-handling system, citing the plants’ root systems as a key factor in cleaning as much as 80 percent of volatile organic compounds in the area such as those coming from solvents and cleaning agents, building materials and carpets. They also estimate an energy savings of $600 per year with the green wall, but also view it as a centerpiece feature of a building and an educational tool.

The wall being planned for the center in Lake County would be 510 square feet, with plants installed in a mesh-like growing medium, rather than soil, with the mesh connected to perforated pipes that are in turn connected to the building’s air-handling system.

Nedlaw Living Walls of Canada is the manufacturer of the green wall system being considered. The company claims to be the only one to use plant walls as bio-filters in controlling indoor air quality. Basically, the “dirty air” is forced into the system and comes in contact with water that is constantly flowing within the wall. The pollutants move from the air into the water and are destroyed by microbes on the plant roots.

Some describe the phenomenon as simply as this: An indoor green wall mimics what is happening with the air we breath outside every day.