Green Roof for Jakarta Urban City

Jakarta and Urban Heat Island

Jakarta, the capital city of Indonesia, not only serve as the center of Indonesian government, but also as business and economy center, bringing many impacts to its development and spatial management. Over the years, Jakarta has attracted more and more people to come to live and work. The first big building built, 1960 Hotel of Indonesia, stimulating the speed rate of growth of another building; after 34 years there are 400 units of over 9 floor buildings, and 577 units of over 7 floor buildings (recorded by Supervisor Department of City Development). [1]

Some of the buildings are concentrated in certain areas, making it have their own block of buildings separated from others. These buildings that are in concentrated in one area creating urban heat island, an area where it surrounded by physical, concrete buildings with glass windows absorbing heat and trapping it, making the temperature is higher than areas outside the concentrated buildings. Since all most all parts of Jakarta are filled with buildings and human settlement, then the urban heat island is also happen in almost all part of Jakarta.

As the consequences, in the beginning of the year 2007, where it supposes to be rain season, in Jakarta, especially, the rain fall was below normal, less than 10 mm per day. Even on January 10 and 11, the temperature was 36°C, much higher than normal highest temperature in rainy season, 31-32°C.[2]

Heat island effect

We have heard just recently in Los Angeles and Paris mortality has risen especially for older people when the temperature reached 40°C. Although Indonesia as tropical country has experience higher temperature than temperate countries, the excessive heat might as well cause death in Indonesia, especially for those live and work in Jakarta. And while researchers are still studying the extent to which heat islands affect temperature-related mortality in a city, excessive heat also can increase the rate of ground-level ozone formation, or smog, presenting an additional threat to health and ecosystems within and downwind of cities, which can lead to the increasing level of stress.

Apart from health issues, heat island effect also raise the issue of energy saving. One of item that gives contribution to excessive heat is the use of many air conditionings by buildings and houses. The airs that come out from air conditioning outside buildings are hot air. Making the outside temperature become higher. The use of many air conditionings requires more and more energy and cost lot of money to pay the electricity charge.

Therefore, a strategy is indeed needed to reduce the excessive heat in Jakarta. There have been several programs carried out by the city government of Jakarta, included Jakarta Blue Sky Program, and Greening. But seems those programs are not giving enough significant result as expected. Then it’s time to spend more time to think about other strategies; installing cool roofs and cool pavements (green roofs), planting shade trees and vegetation right around the buildings.

Green roofs will help to reflect the sun’s energy by minimizing heat transfer to the surrounding air, while trees and other vegetation around building will be able to prevent the sun’s energy from striking windows and walls, so there will be less heat get trapped. This strategy will help to reduce the excessive heat and cut the use air conditioning, which means saving more money.

Green Roof: definition, history and benefits

There some definitions given about green roof. From Wikipedia, A green roof is a roof of a building that is partially or completely covered with vegetation and soil, or a growing medium, planted over a waterproofing membrane. With some limitation, the green roof term does not include roof which are merely green, also container garden on roofs where plants are maintained in pots. Even so, the green roof term also applied for roof that have the same purpose as green roof and considered green, such as solar panels. Green roofs are also referred to as eco-roofs, living roofs or green roofs (a more grammatically correct terminology).

From US Environmental Protection Agency (EPA), a green roof consists of vegetation and soil, or a growing medium, planted over a waterproofing membrane. Additional layers, such as a root barrier and drainage and irrigation systems may also be included. Green roofs can be used in many applications, including industrial facilities, residences, offices, and other commercial property.

Green Roofs as it written in EPA web page has the following benefits:

Green roofs are an attractive roofing option that can reduce urban heat islands by providing shade and through evapotranspiration, the release of water from plants to the surrounding air. They also:

• Reduce sewage system loads by assimilating large amounts of rainwater.
• Absorb air pollution, collect airborne particulates, and store carbon.
• Protect underlying roof material by eliminating exposure to the sun's ultraviolet (UV) radiation and extreme daily temperature fluctuations.
• Serve as living environments that provide habitats for birds and other small animals.
• Offer an attractive alternative to traditional roofs, addressing growing concerns about urban quality of life.
• Reduce noise transfer from the outdoors.
• Insulate a building from extreme temperatures, mainly by keeping the building interior cool in the summer.

The first modern green roofs were developed in Germany in 1960s and since then have spread to many countries in Europe. Modern green roofs, which are made of a system of manufactured layers deliberately placed over roofs to support growing medium and vegetation, are a relatively new phenomenon. It is estimated that today about 10 percent of all German roofs have been “greened.” The same strategy has been also applied in The United States, although they are not as common as in Europe.

Green roofs decrease the total amount of runoff and slow down the rate of runoff flowing off the roof. It has been found that they can retain up to 75 percent of rainwater, gradually releasing it back into the atmosphere via condensation and transpiration, while retaining pollutants in their soil.

One of the main reasons to use green roof is to combat urban heat island. A good example from Chicago's City Hall, which has a green roof installed, temperatures on a hot day are typically 25–80 degrees Fahrenheit (14–44 degrees Celsius) cooler than they are on not green roof (traditionally roofed) buildings nearby. If more buildings would be installing green roofs, then there is great possibility to reduce heat in the city even bigger.

Moreover, according to Penn State University’s Green Roof Research Center, expecting the green roof able to lengthen a roof’s lifespan by two or three times is possible.

After all, installing green roofs mean providing habitat for plants, insects, and other small animals. Especially in Jakarta, where habitat for wildlife is reduced and we barely see birds and butterfly flying around, green roof initiative must be considered to create more green space in city.

Installing Green Roof in Jakarta; The Feasibility

Jakarta, as the center of business and economy circulation, filled with building for offices. Many companies have their center office in Jakarta; some of them even have their own buildings and share it with other small companies. These buildings are most potential to be installed with green roofs, beside governmental buildings and museums. The reasons are because they are mostly the buildings with more floors, means they use more air conditioning, and they are making big profit from their economy activities. Ten biggest companies in Indonesia have their office in Jakarta; they are Astra International, Unilever Indonesia, Bank Central Indonesia, Pertamina, Bank Mandiri, Telkom Indonesia, Chevron Pacific Indonesia, Telkomsel, Citibank Indonesia and IBM Indonesia. [3]Each company has an obligation to allocate their money (profit) for environment and social funds. They can be ask to spent some of this environment and social funds to install green roofs over the top of their buildings to reduce heat that they produce.

Of course the cost for green roof installation will be varying according to the type chosen and the size desired. Green roofs can be categorized as "intensive", "semi-intensive" or "extensive", depending on the depth of planting medium and the amount of maintenance they need. "Extensive" green roofs, by contrast, are designed to be virtually self-sustaining and should only require a minimum of maintenance, perhaps a once-yearly weeding or an application of slow-release fertilizer to boost growth. They can be established on a very thin layer of "soil" (most use specially formulated composts): even a thin layer of rock wool laid directly onto a watertight roof can support a planting of Sedum species and mosses. Depending on the green roof technology used initial cost for a green roof is: extensive green roof: $8 to $20 per square foot and intensive green roof: $15 to 25 per square foot.[4]

Green Roof Costs: An Example of the Typical Extensive Green Roof [5]

#	Component	Costs	Cost Factors
1	Design & Specifications	5 - 10 % (of total roofing cost)	The size/complexity of the project and the number/type of consultants needed.
2	Project Administration & Site Review	2.5 - 5 % of total roofing cost	The size/complexity of the project and the number/type of consultants needed.
3	Re-roofing with root-repelling membrane	$ 10.00 - $15.00 / ft 2	The type of existing roof, type of new roof system, and roof accessibility.
4	Green Roof System (drainage, filtering, paving, growing medium)	$ 5.00 - $10.00 / ft 2	Growing medium (type and depth), pavers (size and type), and square footage of the green roof (project size).
5	Plants	$ 1.00 - $3.00 / ft 2	Season of installation, type of plants, and size of seeds being planted.
6	Installation and Labor	$ 3.00 - $8.00 / ft 2	Equipment necessary to move materials on to the roof (E.g. crane, if rented is: $ 4,000.00 /day), project size, design, and planting methods.
7	Maintenance	$ 1.25 - $2.00 / ft 2 (only for the first two years)	Project size, installation schedule, irrigation system, and plants (type and size) used.
8	Irrigation System	$ 2.00 - $4.00 / ft 2	Since extensive roofs require little irrigation (E.g. sprinkler system or drip system), this component is optional.

Note: The above costs are based on completion of the structural analysis. In this example, the building is in need of a roof upgrade and does not require added structural support. In addition, the roof is accessible for maintenance by ladder. Depending on the size of the green roof project, costs may vary. Source: Design Guidelines for Green Roofs, by Steven Peck and Monica Kuhn, B.E.S. Arch, O.A.A

Installing green roofs is definitely not a cheap program, especially in Indonesia where this type of green strategy is not widely use. But, if see the last profits made by several big companies, their money will able to cover the cost. For example the two biggest national bank in Indonesia, BCA, on semester I 2006 made profit 2, 04 trillion rupiahs, Mandiri Bank made 2,008 trillion rupiahs and Unilever Indonesia made profit 877,9 billion rupiahs. [6]

International environmental organizations such as WWF and CI should be able to become pioneer to promote green roof in Indonesia. By doing this, those organizations will help government of Indonesia in socializing the green roof strategy.

Finally, green roof strategy should be able to be seen as the most feasible option in order to provide more green space in Jakarta and gain its benefits. Green roof discourse must be enriched among government, economics, environmentalists, academics, NGOs, and other stakeholders to gain better understanding for then it will be made as real green action.

Reference and other Sources

Anonim. 2007. Cuaca Jakarta, Fenomena tak Lazim. http://www.republika.co.id/koran_detail.asp?id=278855&kat_id=3
Downloaded on February 14, 2007

· Christiastuti Genuk, dkk. 10 Besar Perusahaan Idaman 2006: “Kebesaran” Mereka Memang Menyilaukan. http://www.wartaekonomi.com/detail.asp?aid=7723&cid=24

Downloaded on February 15, 2007

• Seno Adi. Pemusatan Kawasan Gedung Tinggi di Jakarta. http://www.geografiana.com/index.php?option=com_content&task=view&id=42&Itemid=89

Downloaded on February 15, 2007

· Great Lake Water Institute. Green Lake Water Institute Green Roof Project. Green Roof Installation. http://www.greenroofs.net/index.php?option=com_content&task=view&id=26&Itemid=40

Downloaded on February 15, 2007

· US Environmental Protection Agency. Heat Island Effect. http://www.epa.gov/heatisland/about/healthenv.html

Downloaded on February 14, 2007

· Wikipedia, Free Encyclopedia. Green Roof. http://en.wikipedia.org/wiki/Green_roof

Downloaded on February 14, 2007

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[1] Seno Adi. Pemusatan Kawasan Gedung Tinggi di Jakarta. Geografina

[2] Anonim. Cuaca Jakarta, Fenomena tak Lazim. Republika online

[3] Christiastuti Genuk, dkk. 10 Besar Perusahaan Idaman 2006: “Kebesaran” Mereka Memang Menyilaukan. www, wartaekonomi.com

[4] Green Roof Installation. Great Lakes WATER Institute Green Roof Project.

[5] Green Roof Installation. Great Lakes WATER Institute Green Roof Project.

[6] Christiastuti Genuk, dkk. 10 Besar Perusahaan Idaman 2006: “Kebesaran” Mereka Memang Menyilaukan. www.wartaekonomi.com

Copyright: Karmila Parakkasi 2007