are vertical greenery along an upright structure. Unlike others, we differentiate between 5 types that greatly vary in cost and maintenance. From a botanist and horticultural view Vertical Greenery describes a wide range of upright barriers out of vegetation. In fact, these vegetation walls can be freestanding or supported by a vertical structure.
Traditionally in Europe and "invented" by the Romans are freestanding hedges and rows of trees. Besides the visual aspect, these Green Walls protected against near-ground wind loads, effectively avoiding erosion and sheltering people.
Vertical Green, Form and Function
The term Green Wall gained popularity with art projects from artist Patrick Blanc. After all, he created installations where random perennials grow directly on the wall. Of course, this requires the vertical installation of a growth media where the roots of plants can grow. Because such systems require a sophisticated engineered and permanent irrigation, they are called vertical hydroponic systems. Since, there are many systems on the market, but all have the "hydroponic" element. This categorizes these systems as a piece of art because they are on a drop feed like a patient on a life-support machine in a hospital.
Green Walls, Sustainable and Resilient
In contrast, there are self-supporting solutions where climbing or creeping plants grow naturally up any structure. In fact, such plants are around for more than a 200 Million years and were always an enrichment in any human culture for different purposes including food production. Typically climber plants flexible stems when young that get woody with age. Therefore they are excellent for sustainable carbon sequestration. While climbers follow the sunlight along a structure some may need and additional structure to hold on. Some others develop special organs that are able to grab on the structure and called "self-climbers. resources. Without doubt, climbing plants are extraordinary for shade and sun.
Expertise and Knowledge
Green Roof Technology understand plants. Of course, we also understand economic and ecology. We learned that modest and less flashy options often have a higher value in marketing and certainly an elevated payback for owners and environment.
Overview: Green Wall Types
An Extensive Green Wall (Type 1)
Consists of a self-climber that goes up a structure on its own, as simple as that. This is possible for less than $100 and in around 2 years the plants cover 120-180sf of wall. Because there are choices, it can be a mix evergreen climbers or a summer green climber with flowers and fruits. Especially birds like to nest in these types of Green Walls. Surely, this increases diversity on all levels and over all levels of a structure. A preference for native-only plants in this type of Green Wall can be challenging. Because with urban heat island and climate extremes, a mix of plants can adjust accordingly. At a later time, self climbing Green Walls offer a structure for vines that needs to grab on something. A naturally trellis without ropes, wires.
Extensive Green Walls (Type 2)
Require a structure to grab onto. Of course, such a structure is also design element until it is covered by the vegetation. Thus, design options are unlimited from simple ropes, wires, meshes, and ornamental trellises. Overall an inexpensive solution where diversity and appearance literally grow overtime.
In contrast to other solutions Extensive Green Walls (Type 1 and 2) have the highest ecological and economical benefits. The key benefits of these types of Green Walls are the low installation and maintenance costs. The are affordable for all building owners and the longevity is as long as the structure will last.
Semi-intensive Green Walls
Certainly thrive with comparing plants as in Extensive Green Walls (Type 1 +2). Either self climbing plants or plants that require cables or wire meshes where vines wrap themselves around. Of course both ways it creates a dense Green Wall. However, the main difference is that the plants are not growing from the ground up. Actually, they grow out from planters that are mounted to the facade of building. Ideally, they are in some distance to the facade for an innovative and biophilia design solution.
In fact, the real advantage of such systems are the design flexibility. Very attractive facade combinations are possible, with deep rooting space for the plants and relatively easy to maintain. Because these systems are less technology based and more gravity based, they are a more effective and efficient greenery. Additionally, plant diversity is larger, because the planters also able to host other non-climbing/hanging plants.
In most cases Semi-intensive Green Walls are used to create shade for the building without covering the entire surface of the facade. Semi-intensive systems provide great food sources and habitats for wildlife. Surely they have an outstanding cost-benefit ratio comparing to Intensive systems.
Intensive Green Walls (Type 1 +2)
or vertical Hydroponic Systems consist of small planter cells style, modular elements. Others are custom tailored pocket style facade coverings. Obviously all these types come in many forms and each manufacture claims that they found the revolutionary solution. Intensive Green Walls are not revolutionary, their marketing is. Because of the permanent high input of resources, we consider it as a piece of art. In fact, sustainability and resilience are not the first goal. The emphasize is on the flashy, trendy and "look I am green" effect.
As a matter of fact the plants in intensive Green Wall depend on spoon-feeding from machines with a tremendous input of resources. This high input of resources makes such system very expensive, high maintenance, and vulnerable to environmental changes, in or outdoors. For example some indoor walls need a consistent temperature, humidity and light source and if one fails so does the greenery. Even when the building is upgraded with AC systems it can affect the plants. Additionally, the strictly limited rooting space makes such systems less resilient.
Green Roof Technology watches this "green" industry very closely over the last decade. Vertical indoor urban farms seems the next "innovation" and we believe that such systems will sooner or later adjust to gravity supported systems with less dependency on energy resources. Besides, plants got perfectly adjusted to gravity over 470 million years, we might not change that in our lifetime.
To summarize: Intensive Green Walls remain a piece of art for the people with the big wallets. It is like having a boat. However, when advertising promotes high ecological value in conjunction, it just shows how desperate some are in selling with no real horticulture experience or common sense there is. We do like honest art!
Free Standing Green Walls, Sponge City
Freestanding vertical greenness are as old as human civilization! Whether the Romans create alleys along their road system between cities or the farmers surrounded their fields with hedges or dense row of trees. Of course, they all had one goal. Providing an environmental improvement and enhancement for humans with multilateral benefits.
A Free Standing Green Wall does not need excessive maintenance, no high-tech life support system, and always provide a rich habitat for wildlife. Certainly with hardly any initial costs. The benefits outweigh the costs on the first day as long as the plants have some little space within our dense cities.
Urban heat island effects
can be drastically reduced with Free Standing Green Walls and they require only little space. Overall, this makes this type of Green Infrastructure one of the most efficient solution to combat climate change plus many other social and economic advantages. In fact, in combinations with subsurface bio-retention areas the plants develop faster and more resilient. Free Standing Green Walls combined with a network of parks and Urban Tiny Forests encourage active and healthy lifestyles, improve mental health, prevent disease and provide a place for people to socialize. Certainly, they are considered as an active Carbon sinks. Instead of a specific amount of parking space per building, why not having the double amount of trees per required parking space?
Cooling cities naturally - In May 2013, the European Commission promoted the use of green infrastructure, which it defines as “a network of spaces with public or private agricultural or landscaped natural vegetation.” In response, Barcelona, Spain created a Green Infrastructure and Biodiversity Plan, where green corridors connect green urban spaces such as forests, parks and vegetable gardens. Green spaces within a city and strategic placement of trees in urban areas can cool the air by up to 8 degrees Celsius, reducing the need for air conditioning by 30 percent.