國內薄層綠屋頂成本效益分析

Cost and benefit analysis of extensive green roof in Taiwan

林容安(Jung-an Lin)

指導教授 ： 林鎮洋

國立臺北科技大學/工程學院/土木與防災研究所/碩士(2013年)

摘要

隨著社會經濟型態轉變，人們為了追求更高層次之生活紛紛移往都會區， 99年底常住人口數仍以北部地區最高，10年間增加87萬2千人。都市發展衍生因不透水面積增加導致淹水、熱島效應、空氣污染等問題，當代許多新技術為解決此類問題而被創造，綠屋頂就是其中一項，其環境效益有二十多種，本研究量化「降低地表逕流、節約能源、淨化空氣污染、削減二氧化碳」四種環境效益價值，配合國內薄層綠屋頂案例成本，藉淨現值、益本比與還本年方法，探討建置薄層綠屋頂成本效益。
研究結果顯示，國內增建一千平方公尺薄層綠屋頂，每年可增加19萬元環境效益，包含0.11%的截水效益、8.91 %節能效益、46.73%空污效益與44.25%固碳效益。成本考量設計成本、建造成本與維護成本，四十年共需279萬元。當利率為3.04%、投資年限為40年情境下，薄層綠屋頂成本效益分析結果：淨現值共新台幣76萬元、益本比為1.21、還本年26.52年。
透過調整放款利率(情境二)、投資年限(情境三)、維護費(情境四)，模擬不同情況對投資綠屋頂之影響。結果顯示當投資年限固定為40年，則放款利率小於4.21%或維護費小於建造費之3.54%，較有利推動薄層綠屋頂；若利率固定為3.04%，則投資年限需大於26.52年較有利於推動薄層綠屋頂政策。薄層綠屋頂不僅可減緩都市化帶來的環境污染、惡化問題，亦為值得於國內都會區投資建設的生態工程。

關鍵字

綠屋頂 ； 成本效益分析 ； 截水 ； 節能 ； 空污減量 ； 淨現值 ； 益本比 ； 還本年

並列摘要

In pace with socio-economic transformation, people have moved to urban areas in order to pursue a higher standard of living. By the end of 2010, resident population in Taiwan was still highest in the northern region, a total of 10.7 million people, accounting for 46.3% of the national population and an increase of 872,000 people over 10 years. The economic benefits brought by urban development and rising consumer demand have also spawned an increase in water-impermeable area, energy consumption, and carbon dioxide emissions, resulting in urban area flooding, heat island effect, and air pollution as well as additional social costs in terms of energy consumption and flood control embankment construction.
Much contemporary technology has been created to solve these problems. Green roofing is one of these technologies; among its more than 20 environmental benefits. This study quantified four environmental benefits of domestic cases of extensive green roofing, including reduction of surface runoff, energy conservation, air pollution purification, and carbon dioxide reduction, in terms of three kinds of cost-benefit analysis, namely net present value, benefit-cost ratio, and breakeven year, to explore the domestic cost-effectiveness extensive green roof installation.
Study results showed that every 1,000 m2 of extensive green roofing installed would accrue NT$190,000 in environmental benefits, including 0.11% in water interception, 8.91% in energy saving, 46.73% in air pollution purification, and 44.25% in carbon sequestration benefits. Extensive green roofing cost-benefit analysis results, at an interest rate of 3.04% and investment period of 40 years, were: net present value NT$755,626; benefit-cost ratio 1.21; and breakeven year 26.52 years. Through scenario simulation it can be inferred that an interest rate lower than 4.21% is more favorable to policies promoting the installation of green roofing. Therefore, green roofing can not only mitigate environmental pollution and deterioration problems accompanying urbanization but is also a worthwhile domestic investment in terms of ecological engineering projects in urban areas.

並列關鍵字

green roofs ； cost-benefit analysis ； stormwater runoff ； energy consumption ； air pollution ； carbon emission reduction ； net present value ； benefit cost ratio ； breakeven year

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