People like to make statements – environmentally friendly statements. For such statements, Intensive Green Walls are often utilized. Intensive Green Walls are systems where the roots of plants are in vegetation carrier that is mounted to a vertical surface. Because of gravity it takes some technical efforts to supply the plants with their essential needs like nutrients, water, air, and light.
Picture: Schöner Wohnen
All these systems have bits, parts and materials that are man made and that wouldn’t be required on a natural horizontal area (e.g. Green Roofs). These materials are often made with a high input of natural resources.
The amount of man-made materials and the time needed for the installation makes intensive Green Walls rather expensive. They might start at around $90.00 per square foot but can go up to $150.00 or even more per square foot. An extensive Green Wall (with climbers) is somewhere between $1.00 - $20.00 per square foot. Extensive Green Walls only need a portion of natural resources and patience (what most people don’t have).
More impressive are the operational costs of intensive Green Walls (“average fuel consumption”):
Water: Daily consumption between 1- 1.5 gal of water per 10sf and per day. Pump: 1 kWh/day/10sf
Nutrients: Specially manufactured liquid nutrients per fertigation system $0.05-$0.10 per 10sf/day plus 200Wh/day
Light (if indoors without outside light): Approximately 2 kWh per day and 10 square foot – assuming light duration 14 hours a day.Plants: Indoor greenery typically doesn’t have native plants (where are all these native plants advocates?) and require subtropical conditions that require certain room temperatures (energy) and can cause corrosion with HVAC systems and ducts, besides spores and mildew.
Maintenance: 1 man hour per two weeks per 10 square feet.
I understand that every intensive Green Wall supplier has great arguments and technology to lower operational costs (likely increases the setup costs and failure). Whether by using rain water, grey water or Solar/Wind energy, or even an industrial byproduct for fertilizers, everything is related to the use of natural resources that could be – potentially – used for other and more important purposes than just making a statement or showing (fake?) environmental cautiousness. Intensive Green Walls are a piece of art. Being an artist and working with living plants is not automatically being environmentally friendly nor it means being an environmentalist.
Even so intensive Green Walls likely create environmental awareness to a broad audience; it is still on the back of using natural resources - ineffectively. So you have to decide for you own and keep in mind that replacing an intensive Green Wall (because of operational costs) likely helps to fill landfills.
For me (in my opinion). Intensive Green Walls are a wrong signal because it could be done much more efficient and with the patience of a true gardener who is in harmony with nature.