Vertical Green Installations, Green Walls: Benefits and Risks

Vertical living installations, resulting from the integration of certain types of vegetation into buildings, represent an improvement in ecological and environmental efficiency. They have positive effects not only socially and aesthetically, but also on well-being inside and outside the buildings. For 2000 years, in traditional architectures, climbing plants were planted at the base of walls or grown in pots on main elevations.

They can be used as exterior systems with major visual impact, or installed indoors, benefiting from natural or artificial light under diverse climatic conditions. The selection of plants and growth media used will correspond to the microclimate of the region. Vegetation can root in the surrounding soil, in modular panels attached to the facade, or directly in a wall specially prepared for this purpose, aiming to cover the building with a vegetal layer.

Today, several systems of vertical vegetation are defined, generally known under the generic term green wall. We distinguish green facades (direct and indirect systems) and living walls (passive, active, vegetative walls, and landscape walls), the difference being in mounting systems and cultivation methods.

Living Wall

The living wall system (LWS) consists of modular panels/vegetable planters. Each cell of the system contains its own growth medium such as perlite, polyurethane foam, felt, or mineral wool. If the wall is intended primarily as an independent ecosystem, it is more advantageous to use compost as a growth substrate. Hydroponic culture media is used, with soluble nutrients to meet plant needs.

Functionally, compared to a green facade, most of these systems require a much more complex design, considering many variables, multiple materials, and especially the complexity of the nutrition/irrigation system. Financially, they are energy-intensive, difficult to maintain, and thus quite costly.

The system’s advantage lies in the relatively wide variety of suitable plants, especially evergreens such as ferns, small trees, perennials, and even edible plants. Climbing plants are not used exclusively, allowing for more aesthetic and creative projects. Preselection of vegetation is a meticulous and complex process. It is vital to choose plants according to the environment and the expected lifespan of the living wall. For example, panels with felt-based media have an average life of about 10 years, compared to systems with vegetable planters, which can last over 50 years.

Passive Living Wall

This system derives from green roof structures, with added technological innovations for vertical implementation. Modular systems are used, consisting of rectangular or square panels containing growth media and plant attachment devices. Modular systems are usually pre-planted, with mature vegetation, providing an immediate eco-look upon installation. The growth media contains necessary nutrients, and irrigation is done via a network of tubes through which gravity or system pressure ensures each cell’s moisture. In each project, the structure is isolated from the wall to prevent moisture infiltration.

Overall, there are some common components in all types of living walls, but each project has irrigation, fertilization, and other solutions adapted to local specifics.

Active Living Wall

This concept includes a directed airflow through the living wall, providing significant improvements over the passive living wall. It is desirable that this recirculated air is integrated into the building’s infrastructure, acting as a bio-filter for indoor air and forming part of an ecological air conditioning system.

Vegetation is hydroponically nourished with nutrient-rich water recirculated from a collection tank. Two layers of non-woven textile support the root network mass, allowing roots to develop between them. Plants absorb carbon monoxide from the incoming air, and the system releases fresh, cool air into the building’s air conditioning system. When integrated into the building’s HVAC infrastructure, energy savings can reach up to 30%.

The system can also be applied on a large scale.

Vegetative Wall and Landscape Wall

Vegetative wall (Mur végétal) is the innovation of French botanist Patrick Blanc. Specializing in tropical forest plants, he is well-known as a promoter of green wall concepts. His system consists of two layers of synthetic textile with pockets containing the growth media and the plants.
Due to the weight of the wet textiles, the system is mounted on a metal frame, fixed to the wall and water-insulated. Irrigation is gravitational, with water trickling down through the textile, providing moisture and nutrients to the vegetation.

Landscape walls are an extension of landscape farming. They are built on vertical or steep slopes for soil stabilization, noise reduction, and other purposes. Aesthetically, they play an important role in landscaping projects. Constructed from concrete or plastic geogrids to support plants and growth media.

Benefits and Risks

Benefits appear across multiple areas and scales. Projects covering a large area with vegetation can show advantages at neighborhood or city scale. Others are limited to the building itself. Relevant factors include foliage thickness, material properties, water retention, humidity and evaporation, and airflow in stratification.

Environmental benefits include photosynthesis, air filtration, carbon monoxide absorption, retention of microparticles and dust. Urban noise reduction is also significant. Three factors influence this capacity: growth media thickness, plant coverage, and materials used in the vertical vegetation system.

Aesthetic value is a major factor in green wall design. Buildings in urban clusters can appear gray and monotonous: office buildings, parking lots, standard-design supermarkets, all can be subjects for living wall concepts. Dramatic visual change is achieved, along with substantial environmental improvement.

On the other hand, living wall installations can be quite expensive both to install and maintain. Among vertical vegetation systems, living walls are the most costly due to the combined cost of plants, irrigation systems, and embedded vegetation. Maintenance expenses depend on design/construction solutions, including replacing irrigation and nutrient pipes, damaged panels, or plants. Other potential costs include disposal of maintenance waste, repairs to the building exterior (plaster, waterproofing, etc.), and the list is not exhaustive.

As an alternative, green facades, mainly designed with climbing plants, are a less expensive solution while retaining many of the benefits of living walls.

Every green roof installation we carry out provides the best cost/efficiency/safety ratio, offering green terrace system solutions tailored to your specific project. We provide project planning, system solutions, green roof estimates, and specialized consultancy.