Living Walls: Putting the Green in Green Building

Living Walls: Putting the Green in Green Building

By Kelly Ryan

Living walls, or green walls, are self-sufficient vertical gardens that are attached to the exterior or interior of a building. They can be free-standing or secured to walls and designed to fit both new building projects and retrofits. While being aesthetically pleasing is an obvious benefit, living walls also help LEED project teams earn credits in various categories such as Water Efficiency, Energy & Atmosphere, and Indoor Environmental Quality.

Looking deeper into their benefits, living walls positively impact everything from building protection to improving the health and wellness of building occupants. As discussed in an earlier post, views of greenery and nature while in the workplace have shown to increase productivity levels. Being around nature and plants also proves to have a calming effect on building occupants. Living walls also continuously improve the air quality around them and positively affect the physical health of occupants by absorbing and filtering out common pollutants like carbon monoxide and Volatile Organic Compounds (VOC’s). When implemented on the exterior, they protect buildings by reducing envelope temperature fluctuations. A constant flux in temperature leads to the expansion and contraction of building materials, resulting in deterioration. The framing of a living wall protects against this by allowing the building to ‘breathe’ through a layer of air that separates the wall panels and exterior of the building.

It comes as no surprise that living walls reduce the amount of energy needed to regulate building temperature. When on the exterior, living walls absorb significantly less radiation and can be up to 10 degrees cooler than an exposed wall, reducing the amount of energy needed to cool the building. Since living walls absorb less and reflect more, they can help to mitigate the urban heat island effect, which states that metropolitan areas are significantly warmer than surrounding rural areas due to higher heat absorption rates. Living walls also act as small carbon sinks. As plants grow, they absorb carbon dioxide and store it in their tissues. The high density of plants on living walls removes large amounts of carbon from the atmosphere. Interior living walls also provide cooling during summer months via the process of transpiration. During winter, living walls provide an extra layer of insulation to keep the cold out and the warmth in. Thanks to these benefits and more, buildings with living walls have a much lower carbon footprint.

Types of Living Walls and How they work

Looking at living walls, many questions come to mind….How are the plants staying in place? What irrigation systems are used? Are there specific plants that can and cannot be used? While an unlimited number of designs exist, there are three main types of living walls. The first of these being a panel system where the plants are pre-grown and rooted vertically into panels, which are often retrofitted with a hydroponic system, allowing for accurate irrigation and low maintenance. The second type is very popular for indoor displays and is called a tray system. In this type of living wall, plants are grown off-site but can then be inserted into trays secured onto the wall, which allows for more variability in the design. The final system, termed freestanding walls, are the simplest to install and maintain because of their mobility. Freestanding walls are easy to customize due to their design, allowing for plants to be changed to create new and seasonal arrangements.

Though there are three different types, living walls are all equipped with either recirculating irrigation or drip irrigation systems. Recirculating irrigation systems are by far the most efficient as water is pumped from a remote-controlled irrigation tank and distributed to the plants on the wall, with the excess water being collected in a drain at the bottom of the wall and fed back into the tank for reuse. While drip-irrigation is also designed to minimize water waste, the main difference from a recirculating system is the water comes from an external source, such as city water. Water is channeled to the green wall and distributed to the plants, with the excess water being collected at the bottom and sent back into the local water system. Overall, larger living walls tend to have drip-irrigation systems while smaller ones have re-circulating systems. Regardless of what irrigation system is used, most green wall systems are operated on a timer that tells the system when to turn on/off and how long to run.

     Photo credit: Ambius

With regards to types of plants in living walls, it can vary greatly based on wall design. In general, there is more variability in the plants on interior walls than exterior due to exterior walls being affected by local climate. Other factors, such as the amount of light plants receive, also need to be considered for both interior and exterior walls. Like any other landscaping, living walls require basic maintenance. Though they can be maintained without professional help, many design firms offer maintenance packages with their walls and advise having professionals come out to perform maintenance, especially within its first year of life.

                                                                                                                            Photo credit: Sky Plant Designs

Living Wall Example

Verdical Group’s Downtown Los Angeles office at the LA Cleantech incubator is home to a beautiful example of a living wall (pictured in featured image). Designed by GSky Plant Systems, the 350 square foot interior living wall contributes to the building’s pursuit of LEED Platinum certification. The wall uses a tray system design that contains a wide variety of beautiful plants including Neon Devil’s and Ficus Elastica. Located just off the main entrance lobby, the living wall welcomes visitors with its bright colors and design. Whether on the exterior or interior, living walls and their many benefits transform buildings of all shapes and sizes.