Urban problems at this time has become quite complicated problem to overcome. Urban developments lead to negative consequences in several aspects, including environmental aspects. Urban development needs as a place of living space with activities. Urban population growth also means an increased need for space. Because of space can not be increased, then there is the land use change, which tends to reduce the proportion of land that was previously a green open space. At this time only 1.2% of the world's land is urban, but the spatial coverage and density of cities is expected to continue increasing in the future. The UN has made estimates and states that by 2025, approximately 60% of the world's population will live in cities.
At the time this has been recognized that urban climate has different characteristics from climate surrounding area that still has elements of natural enough. Change elements of the natural environment into an artificial element leads to changes in microclimate characteristics. Various human activities in urban areas, such as industrial activities and transport, changing the composition of the atmosphere which affects the component changes the water cycle, carbon cycle and ecosystem changes. In addition, urban air pollution causes changes in visibility and atmospheric absorption of solar radiation. Solar radiation itself is one of the main factors that determine the characteristics of the climate in an area.
These changes are very important to be taken into consideration in the design and urban planning. But on the other hand, an understanding of urbanization and its impact on the climate-earth system is not yet complete. And in urban development planning in Indonesia, the elements of climate are still regarded as a static element, where it is assumed there is no mutual interaction between climate and land use changes. Climate data is more often used as data to support the claim kesesuian land and location for the development of a regional function, especially for the development of agricultural areas. However, in the design and planning of urban areas in Indonesia, almost never taken into consideration that the planned land use changes will give enormous implications for the climate system.
2. Some Characteristics of Urban Climate
Urban climate is the result of the interaction of many natural and anthropogenic factors. Air pollution, urban surface materials, anthropogenic heat emissions, along with natural factors causing climate differences between urban and non urban areas.
Climate of a city is controlled by many natural factors, both at the macro scale (such as latitude) and the meso-scale (such as topography, water bodies). In the city grows and develops, new factors can change the local climate of the city. Land use, population, industrial activity and transportation, as well as the size and structure of cities, are factors that continue to evolve and affect the urban climate (Figure 1).
Figure 1. Factors that affect the urban climate
(Source: Sebastian Wypych, 2003)
In the early stages of development of the city, most of the land is green open space. However, the need for space to accommodate population and activities, green space is likely to have land-use conversion to the wake. Most of its surface, especially in the city center, covered by roads, buildings and others with a very complex character and distinct character of green open space.
Every material has a surface albedo change the different fractions of solar radiation reflected and absorbed at the surface. In some studies found that the albedo of urban areas is only about 10-15% (for snow albedo is greater than 80%) which means lots of solar energy absorbed by the city to come [2]. In addition, the building materials used for construction of the town is generally characterized by high heat capacity and conductivity. The combination of low albedo and high thermal capacity are anthropogenic factors that create special characters in the atmospheric conditions in the urban areas.From the other side, three-dimensional geometry, the city tends to trap radiation near the surface, and thus lowering the long-wave radiation that may be released. Considerable energy is saved the city during the day, released in the evening with a very slow process. Pendingingan process in urban areas is much slower when compared with the cooling that occurs in non-urban areas which have a considerable amount of vegetation.
High air pollution is another factor that characterize urban areas. Urban air pollution consists of gases and particles / elements / solid grains are emitted by industry, transport, heating systems and others. Air pollutants emitted, change the composition of the urban atmosphere, lowering transmissivitas and increase absorption of solar radiation. In other words, air pollution absorb sunlight and air visibility decreases, so less solar radiation reaching the soil surface.
Generally more polluted than the city center suburb, but it depends on the distribution of industrial location and intensity of use of the streets. During the day, the highest concentrations of air pollution tends to occur at peak hours, ie in conditions where traffic flow is going very high. In the span of one year, in temperate countries, the highest pollutant concentrations tend to occur in the winter time when many hazardous air pollutants emitted due to the consumption of various fuels, to heat buildings, and when the most stable state of the atmosphere in the air to minimize the possibility of mixed. However, in the summer, not infrequently photochemical fog is formed.
In a city, evaporation can be reduced significantly due to an artificial surface does not absorb water as well as a natural surface. Moreover, during the rainy season, water had run off quickly into the city and surface drainage systems in urban areas become dry quickly. Because the water above ground level are few, there is no heat used for evaporation, but is used to heat the atmosphere of the city. Important to realize that the condition of vegetation in an area or region, it affects the air temperature.
The impact of anthropogenic factors on urban climate depends on the size of the city, spatial structure, population, and industry concentration. Small town with buildings that are relatively low and the spread between the green area, no factories or industries, would likely have a smaller impact on climate change compared to urban cities with high buildings.
In addition, the natural setting in which the city is located, has profound implications for the interaction system of local climate and anthropogenic factors. For example, a city located in mountainous areas is often foggy and weak air flow. This causes poor air quality, compounded by frequent temperature inversions.
The town is located in the valley, the formation of inversion occurs because of shading on the basis of landform because of the slope, so that the lower part of the area that gets shade remains cooler than the area that lies on it, and so the air near the soil surface, forming a temperature inversion. Plus, the cold air (and heavier) than the area around the town sloping down by gravity and gathered in the valley or basin, which strengthens the inversion.
Urban climate can be improved by planning the urban structure by reducing the negative impact of natural factors and anthropogenic. For example, through the placement of green areas (eg parks) and local water agencies are strategic locations. The factories should be built taking into account wind direction, so that the air pollution carried by the wind and do not pollute the areas where the need for good air quality sseperti residential area.
3. Global Climate Change
Climate change in this century has become an important environmental issue. Various studies were conducted to identify the various causes of climate change. Other studies led to the identification of mitigation strategies to climate change. Various changes and measurable consequences is necessary to be able to perform the proper response and adaptation to climate change, particularly adaptation that can be done in urban areas. Another important thing that is needed is the exploration of knowledge about how the construction of new cities can meet the criteria for mitigation and adaptation objectives.
By 2030, an estimated 60% of world population will live in urban areas. This is a tough challenge. Mining urban population demands efficiency in the economic system, including the efficiency of the intensity of use of space. Construction of a skyscraper with a high density is one of the efficient use of space. The use of waterproof materials technology to improve the durability of the building, is another form of economic efficiency in urban areas. In fact, high levels of density and use of water-resistant materials with high thermal capacity are all factors that contributed greatly to urban warming. A recurring response to the symptoms of this warming is an increase in energy use for air conditioning, which gives a response back and strengthen the warming phenomenon in urban areas.4. Adaptation to Climate Change in Urban Area Planning
Urban environmental issues arise and warn about the threat of sustainability of the development of cities. In this case, it takes thinking ahead, which is not only oriented to the fulfillment of short-term goals, and the need to reorient the vision of urban development is more to consider environmental factors and sustainable development. Spatial strategy, both for the cultivation and protected areas, needs to be done creatively, so that the conversion of productive agricultural land or from other green areas into non-green areas and non-productive, can be controlled. This is a preventive measure to reduce the rate of temperature change, both locally and globally.
As repressive measures, the response in the system planning and design of urban areas can be done one of them through urban design that takes into account the climate system.
Some urban elements that need to be observed include:
A. Design and construction of buildings. There is the possibility of building and geotechnical problems. The design for ventilation and cooling by natural means, it may be very necessary.
2. Open space and urban ecology. Urban design should incorporate habitat corridors, water bodies and streams, and shade trees. Multi-functional land use may be a key adaptation of urban ecology, with a focus on the new settlement for the planning and maintenance of ecological character.
3. Utility. Remote areas of the service facilities and utilities, as well as coastal areas will be vulnerable area. The greatest influence on the change will occur in the geotechnical and groundwater hydrology, which will affect drainage and water supply networks. Other major infrastructure often at cross-authority authority and requires a collaborative approach.
4. Transportation. Various transportation infrastructure such as railways (especially in coastal areas and areas of potential flooding) of canals, ports and airports have adapted to extreme weather events.
5. Development of drainage system and sewerage. Urban areas will require engineering design that incorporates elements of permeable and soft engineering area.
6. Planning and zoning are sensitive to climate and demanding consistency of decisions based on knowledge of the connection elements and the elements of the climate and the consequences of various changes.
Some things that can be done in space planning:
A. Green space preservation and acquisition
a. Benchmarks for penggambarkan land use, especially of green open space
b. Avoid soil capping through the development of green spaces and water
c. Development of roof greening
d. Development of 'facade greening'
2. Securing local air exchange, which involves:
a. Production of cold air
b. Supply of fresh air
c. Development of green corridors
d. Development of building forms benefit
3. Determine the measures to control pollution
a. To the industrial and commercial
b. On home heating
c. Against traffic
5. The role of Green Space in Urban Micro Climate Determination
The high level of development in urban areas, often ignoring the natural elements like vegetation. Whereas in some studies found that the vegetation has benefits and value to maintain the comfort level of the air [1]. In this case, it is important to consider the needs of urban green space. Physical development of the city itself affect the availability of space for vegetation and its distribution.The results of analysis carried out in several studies revealed the presence of beneficial effects of the impacts of urban green space on the micro-climate, air quality, reduction of energy consumption in buildings adjacent, carbon storage, and also enrich the biodiversity [3,4,5]. It has been recognized also that there are socio-economic benefits that can be derived from urban green space, and its contribution to improving human health.
It is known how climate change may affect the function and structure of green space, which it will eventually have an impact on the urban environment. Knowledge on this subject is important to respond to the effects of climate change through adaptive management strategy, design and planning of urban green space.
Some of the role of green spaces in urban areas related to air quality include:
• Retaining and Solid Particles from the Air Filters
• Absorbent and Penjerap Lead Particles
• Absorbent and Cement Dust Penjerap
• Noise Silencer
• Reduce the Danger of Acid Rain
• Carbon-monoxide absorber
• Carbon-dioxide absorber and Produce Oxygen
• Clutches
• Absorbent and Odor filter
• Coping with flooding
• Climate amelioration
• Light Glare filter
Several models have been constructed and applied to quantify the performance indicators such as green space surface temperature, surface run-off, carbon storage and sequestration. Combination with geographic information systems, generate models of supported devices to explore how the spatial pattern of green space and its attributes such as tree cover associated with its environmental performance [6]. From the results of these studies concluded that green space can be an effective tool to mitigate climate change in urban areas. But there are still many things that have not been explored, such as how much green space is needed, such as what type of green space is needed and how the spatial configuration of the most effective way to improve the urban climate effectively.
6. Cover
Urbanization as a phenomenon that occurs in various parts of the world, is a contributor to climate change. This is because in the process of urbanization changes the characteristics of landscape, from which it is natural to artificial. In this case, the various policies adopted in the planning and urban design and environment, need to consider aspects of climate change will happen. Determination of the development of residential areas, industrial zones, or other cultivated area, of course, will give the consequences of atmospheric conditions on it. Therefore, climatological or meteorological experts should be involved in planning and urban design. Thus it can be expected that in the process of urban spatial planning appropriate reaction to the situation of a polluted atmosphere and comfort will be improved climatic conditions / bioklimatik in urban areas.
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