[GSBN] Airtightness and ventilation

[John Straube]

Too good to be true. A fair bit of research has been done by a strong proponent who once taught at the University of Guelph (Dr Darlington).  He has done some real research and shown there are real benefits, but emphatically you cannot remove ventilation with a living wall.  He has started a local company (Nedlaw) to make and sell these, so he has become a marketing guy, e.g., hard to believe what now is coming out of him :)  You actually may need to increase ventilation to deal with the humidity produced.
Living walls can, like any properly designed mix of plants, remove dust, adsorb some VOCs and chemicals, and even provide a small amount of oxygen.  But they dont reduce humidity (in fact, they create humidity, which is not what you want during cold weather!), and create indoor pollutants like pollen/plant detritus if you are not very careful.
These walls are quite maintenance intensive (low-tech, maybe,incredibly complex, yes), very finicky to get right, and expensive.  A classic case or where a $100 fan plus the wonders of the free outdoor biosystems can provide a more reliable air quality than a $25000 living wall.
As these proliferate as eco-bling in green buildings we are seeing more problems.  Personally, I only have heard complaints about allergies, and humidity.  If you have a dedicated gardener who understands all of this, it could work, but in commercial buildings this is hard.  Recently a case was reported of the water in a waterfall wall supporting and spreading Legionella to visitors to a hospital (no one died, but 8 people infected and some got pretty sick).  
But they sure are beautiful!  We have a big one at Univ of Waterloo, and one in Cambridge City Hall.


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