綠建築生命週期環境衝擊分析暨考量碳排放量之成本效益評估

Abstract

由於環保意識抬頭，綠色概念已逐漸變成環境永續發展的一項重要議題。將綠色概念應用在建築設計以及建材選擇和建造過程中，除了能有效降低污染量外，也能節省將來電力使用的成本，達到省電節能和降低環境衝擊等多重目標。 本研究應用生命週期評估方式針對綠建築，從建材選擇到實際建造過程中，探討各樓層的環境衝擊，再來應用碳足跡的概念，分析其生命週期的碳排放量，並提出適當的減碳策略。本研究最後應用成本效益方法分析採用綠色建材所產生的節能減碳效益，並在符合成本效益及適當情境考量下，提出能降低環境衝擊的最適綠建築方案。 本研究依據台灣大學工學院綜合新館建築規劃圖上的資料進行案例分析與數值計算，以該館舍建造階段所將採用的材料為主要探討對象，透過SimaPro7.3軟體內建Eco-indicator 99方法分析各樓層的環境衝擊，並計算建築物之生命週期碳排放量。針對該擬建造之建築物，本研究發現鋼鐵與PVC建材所造成的環境衝擊最大，其中每一噸PVC的環境衝擊值約為每一噸鋼鐵的四倍，因此降低PVC使用量係使該建物變成綠建築的可行方法之一。本研究經盤查後，發現該建築物自建造至日常使用階段，共會排放646,272 kg的二氧化碳。若選擇卜作嵐材料取代水泥，則能減少22,569 kg的碳排放量，且有3.94%的投資報酬率;如將此建築物加裝太陽能板，日常生活用電則能減少14.56%的碳排放量，另具6.78%的投資報酬率。

As environmental consciousness grows, the concept of green environment has gradually become an important issue for sustainable developments. Applying the concept to green building design including materials selection and its construction can not only reduce effectively the amount of pollution but also save the cost of future electricity usage. Therefore, in the present study, life cycle assessment methods are employed to investigate the environmental impact of a building for the purpose of making it a green building. The assessment covers from materials selection to the actual construction process of each floor of the building, and applies carbon footprint concept to analyze their life-cycle carbon emissions. Then, appropriate carbon reduction strategies are proposed. In the end, this study also applies cost-benefit analysis to find how the usage of green-building materials can achieve the carbon reduction benefits. The demonstrative example in this study is the design draft of the new College of Engineering Building of National Taiwan University. With regard to materials to be used, Eco-indicator 99 of SimaPro7.3 is employed to analyze the environmental impact of each floor of the building. The life cycle carbon emission of the building is estimated. The result shows that the usage of steel and PVC causes the greatest environmental impact, and the impact per ton of PVC is approximately four times that of the steel. Thus, reducing the amount of PVC usage should be considered seriously to make the building be a green one. This study also finds based on environmental inventory study that the building under its current design will emit a total of 646,272 kg carbon dioxide during its life-cycle counting from its construction to its future daily use. If the usage of cement is replaced by pozzolan, the carbon emission can be reduced by 22,569 kg with a 3.94% of return-on-investment (ROI). If solar panel is further installed, the daily life carbon emission can be reduced by 14.56% with an additional 6.78% ROI.