Local environmental issues

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North South Mountain Area

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North South Mountain Area

1. Climatic conditions of Taiwan

Taiwan is situated southeast of the Asian Continent where the Tropic of Cancer (23.5° N) runs across the middle section of the island that divides the island into two basic climates, the tropical monsoon climate in the south and subtropical monsoon climate in the north. The topography is also one of the factors

affecting the climatic condition that the temperature in mountain areas drops while the altitude increases, where mountains over 1,000 meters high constitute about 31 percent of the area of Taiwan. According to the statistics7, Taiwan's annual average temperature is about 24.7 degrees Celsius in the south and

22.6 degrees Celsius in the north, and around 10.8 degrees Celsius in central mountain areas, shown as figure 1.

Figure 1 Average temperature, precipitation, and relative humidity of Taiwan

Secondly, Taiwan receives annual abundant rainfall that the annual precipitation reaches about 2,500mm that also causes high humidity in Taiwan that the average relative humidity is about 78%. Most of rainfalls are concentrated in summer, particularly during the periods when

typhoons visit. Since high temperature and high humidity characterize the climate of Taiwan, the green building of Taiwan should properly reflect such a climatic condition so as to ensure the effective building energy saving design and to meet the actual need of indoor thermal comfort.

2. Local environmental issues

With respect to local environmental issues that Taiwan is confronting, energy is the most

7 The average was calculated based on the database from 1971 to 200. The information can be obtained from the website of Taiwan’s Central Weather Bureau, http://www.cwb.gov.tw. In figure, the data of Taipei were used for North, Kaohsiung for South, and Alishan for Mountain Area.

Material Production, 9.40%

Construction, 0.40%

Transport, 0.50%

Housing, 12.00%

Commercial, 6.00%

Other sectors, 71.70%

building sector, 28.30%

imported energy, 99.30%

natural energy, 0.70%

challenging issue of all. Taiwan is highly dependent on imported energy, which is over 99 percent today. For all energy consumption sectors, the building industry accounts for 28.3 percent of the total energy consumption (including 0.4% building construction, 9.4% material production, 0.5% construction transportation, 12% housing energy uses, and 6% commercial uses), shown in figure 2. Moreover, the microclimate in metropolitan areas of Taiwan has been getting warmer and warmer because of highly urbanization (over 80 percent urban population), shortage of urban green spaces, impermeability of public open spaces, and inefficient building energy saving design. The higher temperature of the urban environment significantly aggravates cooling energy consumption and CO₂ emissions, and accelerates the heat island effect in the city.

The temperature differences between downtown and the suburbs in most of metropolitan areas in Taiwan are 3 to 4 degrees Celsius in summer. According to Taiwan Power Company’s report, air conditioning electricity consumption increases about 6% when the outdoor air temperature increases 1°C. It indicates that the energy consumption of cooling in a building should be improved through better building energy saving strategies, such as heat insulation, ventilation, and sun-shading design.

Figure 2 Current condition of the energy consumption in Taiwan

Second, Taiwan receives abundant rainfalls that the average annual precipitation is more than 2,500 mm. However, the distribution of water resources is uneven, making the water available for use per capita relatively low that the amount of water per capita only reaches one sixth of the world’s average, illustrated in figure 3. Therefore, from saving water resource perspectives, the green building design and its related promotion strategies in Taiwan should cover water

conservation and reuse issues.

Others, 3.69%

Brick, 0.45%

Wood, 0.25%

Steel, 3.87%

SRC, 13.29%

RC, 78.45%

Figure 3 Comparisons of Annual Precipitation and Water Use per Capita in Taiwan

Third, another environmental issue emerges from the immense market of reinforced concrete structure (including steel and reinforced concrete) that occupies 91.74 percent of the entire building stocks in Taiwan, depicted as figure 4. Reinforced concrete construction is typically considered as a high-polluted building method for requiring enormous energy consumption and CO2 emission, natural river aggregate resource uses, as well as and limestone exploitation. In Taiwan, the production of a ton of cement consumes 112 KWH, 134 kilograms of coal, and 450 kilograms of carbon dioxide emission (ABRI, 2008). Moreover, lack of the mechanism for recycling construction wastes also results in environmental pollutions where a reinforced concrete building can generate 0.31 m³ of solid construction wastes per square meter during the construction period and 1.23 m³ wastes per square meter in demolition (ABRI, 2008). The promotion of steel or wood structured buildings accounting for only a total of 4.12 percent, however, still need to be reinforced.

Figure 4 Distribution of all building Structure types in Taiwan (Source: Construction and Planning Agency, 2008)

Besides, in response to about 90% of the time for people staying indoors, issues related to indoor air quality (IAQ), indoor environmental quality (IEQ), and indoor environmental health (IEH) have been addressed and being in-depth explored. For example, with extensive material uses of interior finishing and remodeling for housing, the formaldehyde (HCHO) in building materials and volatile organic compounds (VOCs) emitted in a warm environment can cause a high risk for people to suffer from respiratory and skin diseases. From the perspective of sustainability and livability, a green building will thus be capable of providing a healthy living environment, for both interior and exterior, with proper physical environmental design and quality building material application. Therefore, while various evaluation methods, assessment tools, and certification systems have been developed worldwide, the environmental performance assessment system for green building in Taiwan should be specialized and localized so as to accommodate with the climatic characteristics (high humidity and high temperature), and correspond to its own local environmental issues, including energy saving, water conservation, waste reduction, as well as health..