The most eye-catching feature of the IL Centre is the biowall, located in the main lobby. Three stories high, the wall is both beautiful and functional, acting as a biofilter and a central aesthetic feature of the building.
The wall is a natural air filter which removes VOCs and CO2 from the air as it passes through the wall into the building's office spaces.
The wall is made up of two layers of a porous material attached to a concrete wall. The material is approximately 3 centimetres (1 inch) thick, and is made of loosely-woven plastic that is screwed onto the wall in pieces. Plants are placed into gaps cut into the top layer of material; their roots hold them in place. The roots grow downwards between the layers, and can grow to be several stories long.
Water is pumped to the top of the wall and cascades down between the layers, wetting the roots of the plants. Water is recycled; occasionally nutrients are added, and the system is drained monthly. At the same time, the plants are dusted, wetted, and pruned.
The wall requires no more maintenance than any other indoor landscaping feature. The plants are all chosen to spread no pollen, and the constantly running water and fresh air stop mould from getting a foothold. A vapour barrier has been installed in front of the concrete wall and behind the drywall to stop water vapour from permeating the building.
On each of the three floors, fans pull air through the wall into the building. The fans are triggered by humidity.
Volatile Organic Compounds (VOCs) are produced by many man-made chemicals. They come from petrochemical-based products like industrial solvents, and are also created by car exhaust. The term VOC actually refers to dozens of common pollutants of varying concentrations and emission rates, indoors and out. All are chemically reactive, which makes them great for cleaning and gluing. This also means that they easily escape into the air. VOCs tend to have a high vapor pressure, so they evaporate particuarly well at room temperatures.
While small concentrations of these chemicals arenâ€™t dangerous, over time they can contribute to â€œsick building syndrome,â€ which can include eye, nose, and throat irritation, headaches, and dizziness.
Many VOCs can be reabsorbed into building surfaces fairly soon after theyâ€™re released. However, if there is a large concentration of VOCs in the air, they can hang around; only so many can be absorbed at once. Industrial buildings have filters and scrubbers that remove many of these contaminants from air as it is circulated through building spaces. The downside to using filters or carbon-based materials is that they become saturated and have to be replaced fairly often, with the attendant expense.
Printed circuit-boards, paint, photocopiers, lubricating oils, and refrigerants are all sources of indoor VOCs. Commonly-used materials like carpets and glues will slowly give off pollutants like formaldehyde over the lifetime of a building; new electronics give off methly-ethyl ketone and hexanal. The graph to the right illustrates the kind and concentration of VOCs given off over the lifetime of a printed circuit board.
Here are a few VOCs that are commonly encountered indoors, and the materials they come from:
|Paint, coatings, finishers, paint remover, thinner, caulking||Acetone|
|Paint, adhesive, gasoline, combustion sources, liquid process photocopier, carpet, linoleum, caulking compound||Aliphatic hydrocarbons (octane, decane, undecane hexane, isodecane, mixtures, etc.)|
|Combustion sources, paint, adhesive, gasoline, linoleum, wall coating||Aromatic hydrocarbons (toluene, xylenes, ethylbenzene, benzene)|
|Upholstery and carpet cleaner or protector, paint, paint remover, lacquers, solvents, correction fluid, dry-cleaned clothes||Chlorinated solvents (dichloromethane or methylene chloride, trichloroethane)|
|Acoustic ceiling tile, linoleum, caulking compound||n-Butyl acetate|
|Carpet, moth crystals, air fresheners||Dichlorobenzene|
|Carpet, paint||4-Phenylcyclohexene (4-PC)|
|Deodorizers, cleaning agents, polishes, fabrics, fabric softener, cigarettes||Terpenes (limonene, a-pinene)|
Table from Environment Canada.