By Dr. Anna Zakrisson
Air pollution causes a staggering 4-9 million deaths globally per year. 90% of the world’s population breathes air that exceeds the WHO air quality guidelines. Pollution source reductions are sorely needed, but effective pollution capture is equally impactful. Urban green infrastructure, such as the greenscreen® trellis systems, can act as a pollution barrier and an air pollution capture system, thus improving the quality of life, and health, in urban areas.
Air pollutants can be both natural and anthropogenic (man-made). In urban environments, anthropogenic air pollutants dominate and can primarily be attributed to the burning of fossil fuels from industrial processes, energy generation, and most importantly transportation.
As is often the case, the young and the elderly are the most vulnerable to air pollution. This is partly due to their limited range of movement and high air pollution exposure risks – especially as pollutants are suspended and resuspended in their local environment.
Exposure to fine particulate matter, e.g., PM2.5, has been shown to increase the risk of acute respiratory conditions, lung cancer, heart disease, stroke, and COPD. An increase in the prevalence of Alzheimer’s and other neurological conditions has also been found. In addition, exposure to PM2.5 has been found to increase neonatal mortality.
Apart from immense suffering, The World Bank estimated a total financial loss of $143 billion in 2013 due to lost labor productivity after PM2.5 exposure. The global welfare losses due to PM2.5 were estimated to be $3.55 trillion. In 2016, the World Bank estimated that air pollution-related welfare losses were equivalent to 5% of the gross domestic product in high-income countries.
As such, green infrastructure is both an ethical and good economic decision.
Air pollution is often divided into primary and secondary pollutants. The primary pollutants are directly emitted from the source. The secondary pollutants, on the other hand, are formed from precursors originating from combustion (and other) processes. Further, the formation of these secondary pollutants is often exacerbated by high temperatures, which is bad news considering the increasing urban heat island (UHI) effects.
What we can do to indirectly affect air pollution is to cool our cities. The introduction of green infrastructure would reestablish the natural water cycle, increasing the cooling effect via evapotranspiration.
Pedestrians are often exposed to high levels of air pollutants caused by vehicle emissions that become trapped at street level. Research studies have found that vegetated screens and walls that separate the traffic from pedestrians can significantly reduce harmful air pollutants.
greenscreen® acts as both a direct capture of the pollutants and a dispersion agent , disrupting the airflow and diverting the poor-quality air away from the sidewalk. As an example: green facades were estimated to reduce PM10 by 50% and NO2 by 60% in a study by Abhijith et al. 2017. This can improve quality of life.
In summary: green infrastructure can achieve so much in our cities because it means working with nature rather than against it. GI can cool, reduce pollution, increase biodiversity, reduce energy costs, and re-establish the natural water cycle. Let’s green our streets, one by one!
Modern high-priced artificial plants can look very much like real plants. However, no matter how good the UV protectants are, they will start to look worn and torn as time passes. On the contrary, real plants grow and thrive and will look better and better as the months and years pass; they are alive and developing. Natural plants also bring many secondary benefits to the table that plastics cannot.
Sometimes, clients seem to think green walls and green roofs are something new and fancy. This could not be further from the truth. Humanity has used green infrastructure as workhorses for many thousands of years. Archeological finds show that 2000 years ago, green walls were used to cool the houses in the Mediterranean. Those plants also provided economic value as many also produced fruits.
Green infrastructure has been used to cool factories and other buildings in central Europe since long before the Industrial Revolution. This is not new technology. It is more like a temporary glitch and collectively we forgot how useful it is to have nature work for us passively, and essentially for free. Luckily, the glitch has passed, and the importance of green infrastructure is again widely recognized for its positive effect on the urban environment.
A common misconception is that green infrastructure such as green walls and roofs are only installed because they are attractive. Sure, they are beautiful and can create peaceful refuges that are sorely needed in our urban asphalt jungle, but they are also workhorses that provide essential ecosystem services.
To miss out on these essential services as urban heat islands soar and carbon capture is of the essence is frankly not only irresponsible but can also be economically unfavorable.
Carbon capture: greenscreen trellis systems allow for plant carbon capture due to carbon assimilation into woody stem biomass. Plastic plants are made from petrochemicals and have a terrible carbon budget.
Energetic savings: green walls and green roofs cool a building not only through simple shading but remove heat from the building as the plants evapotranspire (release water into the air). This is an exceptional cooling engine that most of us have experienced when jumping from hot asphalt to a cool meadow. This cooling leads to building energetic savings as the building gets directly cooled and air conditioning units take in cooler air leading to lower energy use.
Stormwater: since real plants evapotranspire, they remove vast quantities of rainwater that never have to be fed into the sewer system. For green roofs, this can be 30-70% of the annual precipitation depending on the profile and climate. This retention capacity results in lower sewage fees in addition to the money saved through energetic savings.
Biodiversity and mental health: green infrastructure also creates biodiverse biophilic islands that are good for both environment and the human mind. There has been a lot of research conducted that shows that humans feel better in a natural setting. If this argument is insufficient, a lot of money is saved as employees miss fewer workdays and patients can be released earlier from hospitals. We work better and we heal better with green infrastructure.
Pollution capture: green walls are also excellent at pollution capture. This is no small feat, as air pollution is the fourth leading global risk factor for death. It has been shown that the greening of external walls reduced harmful PM2.5 and NO2 by 11% to 31% and 7% to 20% respectively.
In summary, plastic plants are outdated, not environmentally friendly, and bring virtually no secondary benefits to the table.
Biophilic design is an architectural approach that aims to increase the building occupants’ connection to nature. This can, for example, mean natural lighting, ventilation, and landscaping.
In our eagerness to build our cities, we have become isolated and disconnected from our natural surroundings, leading to many adverse effects on human health and well-being. Humans simply aren’t suited for lives in sensory-deprived non-natural environments; our productivity is affected, and people get sick and miss work.
This is where well-executed biophilic (“love of nature”) design can be of use and even create a clear return on investment (ROI) through more meaningful and healthy interactions with our environment. But is biophilic design always eco-friendly as often assumed or even promised?
Biophilic design is truly a green marketing buzzword, and as with all marketing buzzwords, it warrants a critical view. As with most things in marketing, there is a true core, but it is far more complex than merely assuming that biophilic design is always “green.” There are no requirements for eco-friendliness in biophilic design. However, biophilic design can still be a powerful tool for urban sustainability and promote human health and well-being – provided it is well executed.
Paul Downton, the eco-city pioneer, summarizes this well: “the eco-city is, per definition, a biophilic city, but biophilic design is not intrinsically eco-friendly.”
The basic framework for biophilic design was created by Stephen Kellert, a pioneer in the field. Kellert defined a framework of principles (three basic elements and 25 attributes) with the aim to support a multisensory built environment with natural or nature-like components.
Read more about the biophilic elements and attributes here.
An essential aspect of true biophilic design is the repeated and sustained engagement with the elements and the space. For example, a space with disconnected biophilic elements such as a couple of potted plants, or a single wallpapered wall with plant motifs, does not create a biophilic project. The biophilic elements need to be connected and interlinked in a meaningful way. Kellert thought of it more like an ecosystem where all the parts interact, including the humans occupying the space.
Biophilic design has a lot to offer in terms of improved life quality and happiness, but also in terms of simple economics. Well-executed biophilic design projects often have clear business cases as it usually is a direct investment in productivity via health. One study showed that 10% of employee absence could be attributed to poor architectural design that failed to provide the employees with the five most vital requirements for basic functioning established by the American Association for Psychology. 10% is a considerable number and provides a huge opportunity for improvements and savings.
Other examples come from the healthcare sector, where many studies have shown that exposure to nature leads to faster healing. In one study, exposure to views of nature reduced hospitalization duration by 8%, translating into significant savings opportunities considering the daily hospitalization costs of over $10,000 per patient.
People are also more inclined to spend more money on biophilic properties – the addition of attractive landscaping with at least one tree added 7% to the rental value of properties in Cleveland, Ohio. The partial view of a lake brought in 30% extra. Green walls, such as cost-effective and low maintenance trellis systems, e.g., from greenscreen®, are great biophilic additions that offer interactive possibilities with the space itself.
Despite the vagueness of the definition of biophilic design, it is a crucial concept. Returning to Paul Downton’s quote above, “the eco-city is, per definition, a biophilic city, but biophilic design is not intrinsically eco-friendly.” Hence, our future sustainable urban dwellings will be biophilic, but we need better standards and more precise definitions.
There are a couple of building standards that support biophilic design, aiming to create a more solid framework with qualitative and quantitative metrics defining what is and what is not biophilic design. Two examples of such standards are the Living Building Challenge15 and the WELL Building Standard16 . The Living Building Challenge only lists qualitative measures, but the WELL Building Standard also lists a few quantitative metrics.
Biophilic design is an incredible topic and the way forward. Still, I firmly believe more standardization must be applied for it to remain meaningful and not end up as a mere greenwashing buzzword.