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Can Planting in the Built Environment Become a Lung for the City?

written by
Kim Jinsoo
materials provided by
Kim Jinsoo
edited by
Bang Yukyung

While we all share the same planet, only a few of us have expressed concerns for the earth’s well-being and about the amount of damage wreaked upon nature. Making improvements to the convenience of our quality of life has now reached a state of no recovery, and we are now aware of the need to unite to tackle this shared challenge of our age described as climate change, or climate crisis. We must review what we have long taken for granted and ask ourselves: ‘does this threaten the environment?’ Correspondingly, what can we ask of architecture and what will improve our quality of life and human dignity in the midst of our ongoing climate emergency? What should we do? By reviewing a building’s life cycle from production, maintenance, and demolition, in the context of climate crisis, we will examine pertinent responses in this issue of SPACE.​ 



STEP 2: During Operation and Maintenance

Question 1: How Much Carbon is Emitted in a Comfortable Thermal Environment?​

Question 2:​ Is a Dam That Is in a Green Building Certification System Working Properly?​

Question 3:​ Can Planting in the Built Environment Become a Lung for the City? 



The ecological green roof case created in Stuttgart, Germany in the early 1970s


Climate crisis and plants
The climate crisis triggered by the current human race poses the most serious threat to humans living in an artificial environment called a city. Unlike nature, which is based on self-resilience, the urban environment created for human convenience has become a space that has lost self-resilience, which is convenient but unhealthy. In concrete-covered cities, radiant heat and accumulated radiant heat caused urban heat islands to become higher than outside the city center, and the vicious cycle of cooling energy operated to cool down the heat was repeated. How can we reverse this environment beyond human control?
Buildings emit carbon in the entire process of birth, life, and death. One alternative to reducing carbon emissions, which is considered the main culprit of the climate crisis, is to restore damaged nature, that is, to expand the green area within the city. However, it is not easy to create green areas in the city center, where land prices have already risen to the point where they have risen. So, the designed method is recording using buildings. Starting with Germany in the 1970s, various methods of growing plants on the roofs, walls, and indoors of buildings were studied and attempted. One of the architects at the forefront of this experiment is Stefano Boerida. Through the Bosco Berticale (2014) project, which means "vertical forest," he has become a world-class eco-friendly architect with a groundbreaking high-rise apartment design that records balconies in the middle of Milan. In an interview, he said, "We have made such an attempt to reduce fine dust and carbon dioxide in response to the climate crisis." So what function do these plants in the city?
Plants balance the atmosphere by generating oxygen during the carbon assimilation process of making carbohydrates with carbon dioxide and water. It also plays a role in lowering the temperature and reducing fine dust by controlling the surrounding humidity through proliferation. Many studies tracking the role of plants in cities in relation to urban microclimate have shown that greening such as rooftop greening and vertical greening not only reduces fine dust and carbon dioxide in cities, but also reduces energy costs of buildings and stores rainwater to alleviate urban heat island phenomena. As a result, major cities around the world, including London, Toronto, Paris, Hamburg, Basel, and Melbourne, have established policies to utilize building recordings. London has decided to apply rooftop and vertical recording to more than half of its buildings in London by 2050 for carbon neutrality and urban health. Hamburg decided to invest more than 600 million euros (about 800 billion won) by 2022 to build a roof structure covering the highway (A7) across the city and create a 240,000㎡ green area on it.

Artificial ground recording
Social interest in plant utilization is higher than ever, from indoor gardening to urban-scale green areas such as New York's High Line. What are some ways to use plants and how fast are they developing? Prior to the discussion, it is necessary to first address the definition of plant utilization. It can be called "artificial ground recording" by collectively referring to recording cases using roofs and walls. It is a term that encompasses all methods of planting using artificial ground (structure), not natural land.
Artificial ground recording is largely divided into three parts: rooftop recording, vertical recording, and indoor recording depending on the space. Rooftop recording is divided into lightweight rooftop recording (also referred to as ecological type and low management type) with low management requirements and heavy rooftop recording (also referred to as management type) for use, and there is mixed rooftop recording. In the 1970s, Germany began lightweight rooftop recording to alleviate the urban heat island phenomenon, and in Korea, where the concept of rooftop recording was introduced in earnest after the 2000s, heavy rooftop recording was mainly applied with emphasis on space utilization. This includes a rooftop garden that plants trees and creates a rest area similar to the garden on the ground.
Vertical recording is a comprehensive concept that includes general wall recording. There are two types of vertical greening, such as ivy, a climbing type in which plants climb up the walls of a building and a structure installation type in which various types of pots such as containers, ports, and nonwoven fabrics are installed. There are various types of structures and plants, and the types of plants vary widely depending on the plant location. When planting outside buildings, environmental adaptations such as Julsa season, snow scent, guardian candles, and seomgirincho are mainly used to maintain green color even in winter, and engaged plants, which are commonly used as indoor plants, are used for indoor greening.
Many methods of planting plants on the exterior of buildings are also being implemented. Patrick Blanc is a world-renowned landscaper in this field. It is well known in Korea that he planted the outer shell of the Busan Museum of Modern and Contemporary Art with a vertical recording method using nonwoven fabrics. Recently, the Korea Forest Service has been striving to create a pleasant indoor environment by creating vertical forests and indoor gardens through life-friendly forests and smart garden projects since last year. Last year, a German designer named Ingenhoven installed a water wall using about 8km of hornbeam in a building called Kövogen 2 in Düsseldorf to improve the urban environment and achieve user comfort at the same time. Interest and importance in artificial ground greening are increasing as a candidate who ran for the Seoul mayoral election last year put forward the vertical garden city as an important election target.

Carbon reduction and artificial ground recording
In April 2019, New York City passed two new bills related to rooftop greening. The name of the bill is the Climate Mobility Act (Local Lows 92 and 94). Looking at the contents and purpose of this bill, which is usually translated into the Climate Mobilization Act, it can be called the Climate Crisis Response Act. The main goal is to achieve the goal of carbon neutrality by 2050 through rooftop recording and respond to the climate crisis. The reason why New York has turned into an active attitude toward sustainable use of the rooftop can be clearly seen by listening to the story of Rafael Espinal, a New York lawmaker who proposed the bill.
"We pass the bill today to make the skyline more beautiful and to improve the quality of life of New Yorkers over the next generation. We have seen the innovative advantages of rooftop greening in many cities. In other words, rooftop greening makes our city a good place to live by easing the urban heat island effect, cooling down the city center, saving energy, absorbing air pollutants, reducing excellent runoff water, promoting biodiversity, and increasing soundproofing effects."
The utility of artificial ground recording is not limited to this. Idle spaces can be used for gardens, exercise spaces, urban agriculture, etc., and noise can be reduced and the value of buildings can be increased. It can also protect waterproof and concrete layers to reduce maintenance costs and extend the life of buildings. All of these advantages have great implications in that they not only reduce carbon and fine dust in terms of building operation and maintenance, but also achieve the comfort of life.

The ecological green roof created in residential complex, Germany 
The task and future of artificial ground recording
So far, we have looked at the impact of artificial ground green on buildings and cities in the era of the climate crisis. Why can't artificial ground recording be activated despite these advantages and values? Concerns about high construction costs, maintenance costs, and defects clearly acted as unfavorable conditions. After Stefano Boeri's Bosco Berticale succeeded, various vertical recording buildings have been built around the world imitating it. However, the greenery was only for a moment immediately after the project was completed. Many buildings that did not delicately design a sustainable environment in which plants could grow healthily failed to manage. This is evidenced by high-rise apartments in Chengdu, China, which were resented by mosquitoes because they were not drained, and many vertical greening cases that were planted without considering the climate and died throughout the winter.
Then, is there no breakthrough? There are several conditions necessary for this. The first is the development of technology. The high cost of maintaining a green space is the same as continuously emitting carbon. As in the case of Germany, which creates renewable energy such as sunlight and recording together on the rooftop, research on construction methods is needed to be linked with other energy reduction methods at the design stage. In addition, in the case of vertical greening, seasonal changes and the environment in which plants do not grow well in the vertical direction act as a major obstacle. Solutions to develop installation technologies that can overcome this and reduce installation costs should be continuously researched and developed.
The second is institutional support. The rooftop greening method has developed technology to store a lot of rainwater and to help plants grow well in low soil depth. Nevertheless, since there is no incentive for quality, low-quality rooftop recording made at low cost is dominated, and there are many cases where it has been neglected as a hideous object because it is not managed. This neglected recording space rather causes carbon generation. For the completion of the building, it is necessary to escape from the act of forcibly recording to meet specific certification standards. It is urgent to prepare a system such as guidelines that induce effective recording methods to be established in the field.
The last condition is social awareness. A healthy ecologically operated green space contributes to the public interest aspects of carbon neutrality and urban landscape improvement, while also playing an important role in enhancing the value of buildings and improving the comfort and quality of life of users. Breaking away from the stereotype that it is expensive and difficult to manage, efforts are needed to actively find and implement various spaces that can be converted into green areas from rooftop, walls, and indoors.

It is still too early to conclude hastily about the utility of artificial ground greening. This is because it is difficult to quantitatively determine the carbon reduction effect with only artificial ground recording. It should be evaluated from the overall perspective of reviewing various conditions that can create synergy in proportion to the time axis of maintaining the building. When research and development for appropriate technology and design, institutional traction and social perception changes operate, artificial ground recording may be an alternative to the climate crisis and a key to the self-resilience that mankind has lost. Perhaps the reason why the world is calling for carbon neutrality is ultimately to return our environment to a part of the global ecosystem where healthy lives are maintained.​ (written by Kim Jinsoo / edited by Bang Yukyung)


The roof garden of Highline in New York 

Kim Jinsoo
Kim Hyojin, a Ph.D. in civil engineering, joined the Korea Housing Corporation in 1993, served as the head of the LH Environmental Energy Research Department and the Green Growth Research Department, and is currently the head of the LH Construction Technology Research Department. Professional research is being conducted in areas such as structure dismantling, construction waste, and climate change response, such as the head of the eco-friendly dismantling research team of the Ministry of Land, Infrastructure and Transport and the vice head of the construction waste research team.