All in all, the Biofilter concept is a strong one, and gaining momentum. Alan Darlington, a professor of environmental biology at the University of Guelph estimates that they can save 0.3 to 3.5 kilowatts per person in heating and air conditioning in the height of summer and winter. This is because less outside air is needed to maintain air freshness, and therefore, less heating and cooling of that air is needed. Biofilter systems are in place at Queen's University in Kingston, the Toronto and Region Conservation Authority head office, and an office building in downtown Toronto, in addition to the huge installation at The University of Guelph. :: Green Wall Biofilters
If you've ever found yourself suffering from respiratory symptoms -- asthma, chest congestion, or infections -- in your workplace or home, you may have a building with "Sick Building Syndrome". Sick buildings are those that encourage respiratory illness by concentrating Volatile Organic Compounds (VOCs) and allergens like mold spores in poor ventilation areas. These VOCs come from adhesives, paints, cleaners, and building materials which off-gas long after the building is completed. Until recently, few remedies for this problem were available. But now, a promising low cost, and beautiful solution is available with "Biofilters"...The secret to these walls of plants is root microbes. Plants naturally absorb VOCs from the air as a by-product of collecting their CO2 food. These chemicals build up in the roots and soil surrounding the plants, and if they aren't' broken down, become toxic. So, over millions of years, plants have developed symbiotic relationships with soil microbes which break down these chemicals into harmless bits like CO2, nitrogen, and oxygen. Some of the by-products become food for the plants, and others, become nice additions to the atmosphere for humans.