Have you ever been to the 6th floor of Queen Sunheon Building? If you go there, you will be surprised by the beautiful scene on the roof. It is filled with green trees and plants like a garden. Like the roof of Queen Sunheon Building, roofs in Korea are changing their appearance and function by being afforested. A newly-created word, ‘Roofterior’ (a compound of roof and interior), which means specialized roof design, is gaining popularity.
What is Green Roofing?
‘Green roofing’ means making a roof green by creating artificial ground on the roof and planting trees and grass without changing the structure of the building. Green roofs have different characters depending on the general landscaping. A roof garden can be designed in various ways according to its function, structure, and appearance. In addition, it has many uses such as shelter, vegetable garden, flower bed, or a place for events and recreation.
Recently, roof gardens have come into the spotlight as one way of dealing with city environmental problems because of their environmental benefits. Both national and local governments are trying to plan a legal system to promote roof gardens.
The Origin of Roof Gardens
The origin of roof gardens can be traced back to the 19th century in Germany. People started to cover their roofs with soil to prevent fires. As plants were spread by hayseed which flew through the air, green roofs were formed naturally. Green roofing was encouraged in the 1970s in order to save energy after the oil shock.
The first official green roof in Korea was the ‘Sky garden 21’ which was built in 1998 on the Kyeongdong building in Bundang. Since that time, roof gardens have continued increasing. Seoulites(people living in Seoul) took more interest in the idea after the city began a project to promote green roofs in 2002.
Roof Gardens in Other Countries
Advanced countries like Germany and Japan became aware of the value and utility of green roofs earlier than Korea. Therefore, they have many more roof gardens than other countries. Their local governments promoted green roofing actively by supporting half of the expense of installing a green roof. In the case of Japan, newly constructed buildings in Tokyo are obliged to cover 20 percent of their roofs with greenery. Also, in Germay, 42 percent of local governments give economical incentives for green roofs. Chicago in the United States subsidizes up to 5,000 dollars when people create a green roof.
Benefits of Roof Gardens
Roof gardens have an important environmental benefit. They can reduce the heat island which makes the temperature in the city higher than in the outskirts. Tokyo officials have said that if 83 percent of roofs have trees planted on them, the highest temperature will fall by about 0.2~1.4 ℃. Also, plants which grow in the garden purify the air by increasing the density of oxygen and decreasing the density of carbon dioxide. In addition, if a garden has soil up to 10㎝ deep, it stores 20~30ℓ of rainwater per 1㎡, which prevents flooding and rainy spells. Professor Kim Seong-hwan of Dong-A University said that a roof garden is not just a garden but an important alternative plan for solving international environmental problems such as global warming.
In addition, roof gardens help to save energy. By building a roof garden, people can reduce their costs of air conditioning and heating. It is the roof which wastes the most energy in a building. If people make adiabatic floors by planting vegetation, they can save 10 billion won in energy bills for air conditioning and heating per year.
There are other benefits. A roof garden protects the building from strong ultraviolet rays and acid rain. Also, it makes city more peaceful by absorbing 20dB of noise with its sound absorbing power. It plays a role as an educational place where people can learn about the growth of plants and ecology. In addition, a roof garden provides attractive surroundings in which people can rest. Not only that, it improves the value of the building and thus offers extra income by increasing visitors. For all these reasons, buildings in Seoul with roof gardens increased from 128 in 2007 to 185 in 2008.