Green walls, also known as living walls, protect buildings by reducing temperature fluctuations. A constant flux in temperature can lead to the expansion and contraction of building materials resulting in cracks, fractures and general deterioration.
They also waterproof the exterior and allow the building to ‘breath’. The system keeps the rain off the building while allowing moisture to escape and protects from harmful UV radiation and corrosive acid rain. This, in turn, increases the integrity and longevity of the building’s exterior.
The average person spends over 90% of their life indoors and many are constantly being exposed to indoor air pollution. This includes toxic fumes such as formaldehyde, volatile organic compounds (VOCs), trichloroethylene, carbon monoxide, benzene, toluene, xylene and others.
Plants absorb and clean pollutants from the air and certain tropical species are more efficient than others. Green walls can contain plants which are best at improving air quality. Plants can remove portions of these airborne toxins and an entire green wall can contain walls of plants, all of which filter air and create energy-rich oxygen. The common indoor air toxins are:
Formaldehyde (CH2O is found in products such as furniture, wallpaper, cardboard and facial tissues. It is also used in some plastics, paints, varnishes, dishwashing liquids, fabric softeners, and cosmetics, such as nail polish. It enters the indoor environment through natural sources such as forest fires and certain human activities, including burning tobacco, gasoline and wood. As a result of being in so many common products and so prevalent in the environment, it is present in its breathable gas form in virtually all homes and buildings. Studies have suggested that people who are exposed to low levels of formaldehyde for long periods of time are more likely to experience asthma-related respiratory symptoms, such as coughing and wheezing. In higher amounts, formaldehyde is known to cause cancer of the nasal cavity.
VOC’s or volatile organic compounds are found in all petroleum products; however, there are many other sources such as flooring adhesives (used for carpeting, hardwoods, etc), paint, furniture, wall materials, electronic equipment, cigarette smoke, household cleaning products and even air fresheners! The main reason we should be worried about VOCs is because they are the primary precursor to the formation of ground-level ozone and particulate matter in the atmosphere which are the main ingredients of the air pollutant referred to as smog. The negative health effects of smog are well documented.
Trichloroethylene (TCE) is a common indoor pollutant being released from paints, dry cleaning, adhesives, pesticides and the ink in copy machines, faxes, and printers. Short-term exposure to TCE causes irritation of the nose and throat and depression of the central nervous system. Higher concentrations have caused numbness and facial pain, reduced eyesight, unconsciousness, irregular heartbeat and even death.
Carbon monoxide (CO) is a dangerous gas which is produced from open fires, gas stoves, appliances and heaters. It is also present in high concentrations in cigarette smoke and vehicle exhaust. Low-level exposure causes dizziness and headaches while more acute exposure can lead to death because CO actually prevents the delivery of oxygen to the body’s cells.
Benzene (C6H6), Toluene (C7H8) and Xylene (C8H10) are found in the vapour of products such as gasoline, oils, paints, glues, inks, plastics, and rubber, where they are used as solvents. These three pollutants also enter into the composition of detergents, explosives, pharmaceuticals, foams and dyes. They are skin and eye irritants and are known carcinogens, in connection to human leukaemia.
According to the Environmental Protection Agency: “people living and working in buildings of manmade materials inhale over 300 contaminants every day”. Concerns about these contaminants arise from the hypothesis that, when combined, the toxicity of hundreds of different chemicals can “add up” to create major health hazards.
How green walls can help
Research undertaken by the National Aeronautics and Space Administration (NASA) proves that plants are capable of cleaning indoor air of the toxic chemicals that are common in modern buildings.
Dr William Wolverton, NASA’s principal investigator researching air quality on space stations, says that chemicals such as formaldehyde and carbon monoxide can be removed from indoor environments by the plant leaves alone. VOCs, TCE, benzene, toluene, xylene and numerous other toxic chemicals can be removed by the roots of the plant (or by the microorganisms living around the roots which degrade and assimilate these chemicals). Through the process of photosynthesis, plants take in carbon dioxide and release oxygen. An increase in oxygen helps to keep us awake and alert. You will benefit from a dramatic increase in air filtration and oxygen production and do so using much less valuable floor space.
Naturally, everything heats up when exposed to solar radiation. A building is no different. During the summer it leads to an increased demand on cooling systems and the energy they require. Studies have shown that the surface of an exterior green wall is up to 10°C cooler than an exposed wall, therefore considerably less heat is radiated inward. Not only do green walls reduce cooling requirements but they also help to mitigate the urban heat island effect.
Interior green walls also help to save energy during the summer. Through the process known as transpiration plants actually cool their surrounding environment slightly. With each additional plant this increases and therefore a green wall, with hundreds of plants, can reduce the temperature of a room anywhere from 30C to 7°C. Some studies have shown that interior green walls can cut electricity bills by up to 20%. During winter a living wall system acts as extra insulation. There is an additional layer of air between it and the wall which reduces the amount of heat escaping and cool air coming in.
Health & Wellness
Living in urban environments, we are surrounded by concrete, traffic, noise and pollution. This is not healthy. It has a profound impact on our physical and mental wellness. Greenery softens this hard environment, acting as a tonic to ease stress and fatigue. Green walls provide a substantial and spiritual connection to nature which is missing in the modern concrete jungle.
Studies have shown that simply having a view of greenery increases workplace productivity. Furthermore, having plants indoors reduces symptoms of discomfort. This decreases the number of days off due to “sickness”. Gardens that are incorporated into hospitals calm patients leading to the improvement in clinical outcomes and shortened stays.
Air quality is an important aspect of health and wellness and plants have been proven to filter and remove toxins. They also add energy-rich oxygen. With each additional plant, these benefits are multiplied. A green wall, with thousands of plants, therefore has a major positive impact.
According to some optometrists, the human eye can distinguish between 2,000 shades of green, but only 100 shades of red. Scientific reports carried out at American and European Universities indicate that by simply having a view of plants in a working environment give positive physiological responses. This translates into greater employee efficiency which results in increased earnings.
Another study was carried out at the Norwegian Agricultural University with the goal of assessing the effect of plants in an office on the health and symptoms of discomfort among office personnel. During randomized periods the subjects were exposed to bare office environments and to ones where plants were within view. It was found that during the periods that plants were present, symptoms such as a cough, fatigue and dry/itchy skin decrease at 37%, 30% and 23% respectively.
If people have a view of foliage and feel healthier at work because of plants being present then the number of days off due to ”sickness” decreases. It has been proven that hospitals which incorporate gardens have been shown to calm patients, improve their well-being and foster improvement in clinical outcomes such as reducing pain medication intake and shortening stays. This reduces the number of people in hospitals, the staffing and medicinal requirements.
Green walls are at the cutting edge of design trends. They have been featured in upper-end hotels and restaurants, designer retail stores, chic spas, exclusive clubs, basically, any place looking for distinction – something that makes them stand out from their competitors.
Living walls are also marketing tools that can be used to promote a company’s green image. For example, car dealerships have installed green walls right before the release of new hybrid or electric vehicles. This speaks directly to the green consumer.
In addition to being a marketable green feature, a living wall can increase the property values of homes and businesses. Studies have shown that by simply having plants in and around a building or home can increase real estate values.
Having greenery in retail shops, malls, restaurants, cafes, bars and other businesses, can increase the number of patrons. Studies have also attributed significantly higher occupancy rates at hotels which incorporate gardens and plants compared to those without.
Have you ever been in a large room full of people talking and you feel like you have to yell so the person next to you can hear? Did you feel overwhelmed by the amount of noise and left the room with a ringing in your ears? This is due to the echo created by all of the people’s voices or music bouncing off the walls, ceilings, floors and other objects in the room.
Studies have shown that the leaves of plants attenuate sound by reflecting, refracting and absorbing acoustic energy in small amounts. The amount of noise reduction is proportional to the number of plants that are present in a room. Green walls contain such a large number of plants that the acoustics of a room can be substantially improved.
Plants are sometimes used in buildings for their acoustical benefit alone. In Germany, a green concert hall was constructed which incorporated many plants. The high density resulted in such a good acoustic quality that the German Broadcasting Station relocated to use the room for newscasting.
Plants and trees have been used for years as barriers against traffic and other urban noise pollution. Green walls built on the exteriors of buildings will do the same. They insulate against noise, vibrations and reduce sound penetration. In addition, they help absorb the echo bouncing off buildings and dampen the noise pollution of modern cities.
Green walls help buildings become more energy efficient which leads to a decrease in carbon emissions. They also mitigate the urban heat island effect, absorb and filter stormwater, reduce pollution and act as carbon sinks.
In addition to using a wide range of native and locally-adapted vegetation on outdoor walls, beneficial organisms, such as small birds, butterflies, bees and ladybugs are attracted to these plants. This reduces the demand on cooling systems. In winter living walls provides an additional layer of insulation keeping the cold out and warmth in. These features act to reduce the carbon footprint of a building.
The urban heat island effect is defined as a metropolitan area which is significantly warmer than its surrounding rural areas. A large portion of this heat comes from the multitude of hard surfaces, including exposed walls, which radiate the sun’s energy. Vegetation has been shown to reduce this effect and the negative impacts it has on life quality.
Green walls naturally absorb and filter stormwater. It is also possible to irrigate them using collected rainwater. The roots and microorganisms living around them utilise and remove pollutants found in the water. Excess water is eliminated.
As plants grow, they absorb greenhouse gases from the atmosphere and store it in their tissues, basically acting as carbon sponges. The way we arrange the plants in our living wall system is quite dense which means that we are able to have many in a small amount of space.
Outdoor living walls can be viewed as mini-ecosystems; the incorporation of such a variety of plant species supports many beneficial organisms such as butterflies, bees, ladybugs and hummingbirds.