Architects and interior designers have long advocated the installation of greenery within indoors environment in order to impart a much-needed sense of nature to enclosed and occupied areas.
In addition to enhancing the aesthetic appeal and natural atmosphere of building interiors, large-scale indoor plant installations can also improve living conditions for human occupants while raising the energy efficiency of facilities themselves.
Living walls are one of the most convenient and effective means of bringing large amounts of greenery to building interiors, while also maximising the benefits associated with the installation of plants indoors.
First developed by French botanist and artist Patrick Blanc over three decades ago, living walls are essentially vertical gardens that provide an upright foundation for the roots of the plants they support.
The chief distinction between the modern living wall and conventional green facades such as ivy walls is that the former consist of containerised plants arranged in multiple layers of vegetation, while the later are host to climbing plant species that spread across the vertical height of the structure, yet are anchored by their roots in a bed of soil at the base.
Because living walls are comprised of containerised plants distributed across the height of the structure, they make use of vertical irrigation systems for the delivery of water and nutritional sustenance.
The most obvious advantage of installing a living wall within an indoor setting is its ability to bring a large amount of greenery to an enclosed space that might otherwise be devoid of organic features.
Living walls can bring other major benefits to building interiors, however, chief amongst them their ability to serve as vertical “biofilters” that can improve air quality and thus enhance environmental conditions for human occupants.
The ability of living walls to improve indoor air quality is particularly relevant given recent studies that show a strong relationship between atmopspheric conditions and human cognitive performance.
Harvard University’s landmark COGfx study, for example, found that high levels of volatile organic compounds (VOC’s) and carbon dioxide can dramatically impede test performance in controlled environments.
Living walls serve as far more effective biofilters than conventional potted plants that are situated at ground level, because of the fact that the ability of flora to cleanse the air depends upon the many microbes with which they share a symbiotic relationship.
These microbes flourish not just on the roots and leaves of plants themselves, but also in the adjacent environmental media, like soil and water, that are the base prerequisite for organic greenery.
The microbial colonies that thrive in the soil of potted plants are by definition contained within plastic or ceramic vessels, thus impeding their ability to interact with the atmosphere and influence indoor air quality.
Livings walls are essentially hydroponic structures, however, that use pumps to channel water and associated nutrients to the top of the installation, before allowing it to trickle back to the bottom through the porous materials used to anchor the roots of the containerised plants.
The vertical alignment of living walls in combination with the porous media used to anchor plants permits far greater interaction between circulating indoor air and any soil or root microbes with filtering and cleansing propensities.
The enhanced air cleansing achieved by living walls can in turn dramatically raise the efficiency of HVAC systems by reducing their energy burden.
HVAC systems traditionally adjust the temperature of indoor settings using new air sourced from the external environment. This external air must be conditioned prior to being channeled into into the building interior, which is a process that incurs a heavy energy cost. As a consequence HVAC systems often over 30 per cent of a building’s total energy consumption.
Living walls can cut down on the energy consumption of HVAC systems by instead providing them with filtered air from the same, indoors environment, that already possesses temperature or humidity levels far closer to those intended.
The efficiency gains achieved by combining living walls with HVAC systems can reap huge economic benefits of facilities owners. A six-storey living wall designed by Diamond Schmitt Architects proved capable of meeting all the humidification needs of the University of Ottawa faculty building where it was installed, enabling the campus administration to fully offset the project's capital costs.