We design our walls for long life, active filtration and ecological integrity.

Basic green walls often feature potted plants fed by a system of water trays, which means the plants are easy to source and replace. It also means that the roots of the plants are constrained, subject to too-dry or too-wet conditions and unable to clean air efficiently. When evaluating the functionality of green walls, remember this: it is the microbial action in the root network that cleans the air; the plants are simply sustaining the environment. Anything that constricts or isolates the root system of a living wall will also limit your opportunity to put nature to work.

Other walls employ hydroponics like we do, but root their plants in growing substrates that degrade over time or cannot structurally support the large and woody plant selection that has made our wall portfolio so remarkable. We use a proprietary growth medium that is both sturdy enough to hold heavy plants and has stood the test of time.

We build our biofilters with two layers of growth media, which allows the root network to grow freely in between. This design creates optimal root exposure to the air flow that is drawn through our system; microbes on the roots are doing the dirty work of eating air contaminants – also known as biofiltration. Keep in mind that green walls with contained roots cannot replicate this natural process.

Nedlaw Biofilters actually combine three technologies – biofiltration, phytoremediation and hydroponics – into a unique system designed specifically to deal with issues of indoor air quality.


Biofiltration is the passing of a contaminated air stream through a biologically active area where beneficial microbes use pollutants, such as VOCs, as a food source. A Nedlaw biofilter moves the air stream through on-boards fans or by connecting to an HVAC system.


The second technology is phytoremediation. Normally, this field technology uses green plants to speed the recovery of contaminated soils. This is how plants facilitate the beneficial microbial activity: the products of photosynthesis – oxygen, sugars and proteins are shuttled to the roots where a substantial amount is ‘leaked’ to the soil. The increased nutrient availability leads to enhanced microbial activity.


As you probably know, hydroponics is the process of growing plants in liquid nutrient solutions rather than soil. Decades ago, we developed the Nedlaw Biofilter as a vertical hydroponic plant wall. Our system pumps water from a basin at the bottom of the wall to the top; the trickling water provides nutrients and adequate moisture for the plants and root system to thrive. Recycling the water in this closed loop system is much more resource efficient than the constant spraying and watering required by soil-based plant walls.