Cleaning Indoor Air with Nedlaw Living Wall Biofilters


Living Wall Biofilter at Drexel University in Philadelphia, PA


The Air Quality Dilemma

North Americans spend over 90% of their time indoors and as much as 30% of the energy consumed by the building is used to generate an adequate environment for these occupants. Facility managers are therefore caught in the bind of trying to provide a good environment for their clients while trying to run the building as economically as possible. An Indoor Air Biofilter Living Wall helps solve this dilemma.

Indoor Air Biofilters

The Nedlaw Biofilter is the result of close to 20 years of research at the University of Guelph. This research started at the Canada Life Environmental Room at the Toronto head office of Canada Life Assurance (now part of GWL) in the mid ‘90’s. At first glance, the living wall appears as a vertical hydroponic green wall containing a wide range of foliage tropical plants.


Schematic of Indoor Air Biofilter


However, the plant wall is actually an integrated part of the handling system for the building. Air is actively forced through the wall of plants where pollutants such formaldehyde and benzene in the air are biologically degraded into their benign constituents of water and carbon dioxide. The clean air is then distributed throughout the space by the mechanical system. The biofilter is an adaptation of two industrial processes. The first being biofiltration which is the passing of contaminated air stream through a biologically active substrate where beneficial microbes use the pollutants (such as VOCs) as a food source. The second is phytoremediation; where green plants help the growth of these beneficial microbes.


The indoor air biofilter can be thought of as a biofilter with the plants integrated within. Behind the scenes, a pump constantly circulates water and nutrients from a reservoir at the base to the top of the wall. The water then flows down the wall through a porous synthetic root media in which the plants are rooted. Air from the occupied space is actively drawn through the plant wall by either the HVAC system or on-board fans and then returned to the occupied space. As the dirty air from the space comes in contact with the growing (rooting) media, contaminants move into the water phase where they are broken down by the beneficial microbes.

Indoor Air Biofilters Improve Air Quality

The biofilter improves the indoor environment through a number of ways; first in terms of its impact on air’s contaminant levels. A single pass through the Nedlaw Living Wall removes 75% of the harmful chemicals, generating air the same quality as found outdoors. University studies indicate that a properly sized Biofilter can reduce the indoor pollutants by 30%. The biofilter can generate this clean air for up to 90% less energy than conventional ventilations systems in the heat of the summer or cold of winter.


VOCs Removed with one single pass thru our biofilter


Other Benefits of Indoor Air Biofilters

The living wall improves the aesthetics of the indoor space. There are increasingly strong links between indoor air quality, greening the indoor space and the well-being of the occupants. Greening the space and improving air quality reduces the stress levels, increases the productivity and reduces absenteeism.


The biofilter also affects the sound environment of the indoor space. In office spaces the “business buzz” is steady and can in itself add to employee stress. The sound of abatement and white noise feature