英文篇名
Carbon and Water Inventory with Environmental Impact Assessment Corresponding to Waste-Reduced Strategy on the Case of Underground Pipe-Jacking Excavation
作者
張晨揚、陳立憲、申永順
關鍵字
生命週期評估、碳足跡、水足跡、環境衝擊、管推工法、公共工程經費電腦估價系統
摘要
邇年來因氣候變遷引致之環境生態困局;與能、資源短缺所造成之生存危機,各項產業無不尋思解決之道。以碳排放為例,臺灣高居世界第21名(2014),其中土木建築相關事業之碳排高佔居總量之33%;再以水資源為例,臺灣缺水排名為全世界18名(2015),其中營建工地用水平均多達10-20ton/day(2013),亦亟待改進。故相關工程不僅應就傳統管理面向之安全、進度、成本與品質作考量;更應對碳排放量與水資源消耗量進行減量策略且加以探討。
因維生管線攸關國家競爭力之民生基礎建設;且地下開挖工程不確定性最高,故本文以土木營造業之地下開挖的管推工程為例,先行檢討盤查之依據與功能單位之確立後,在規劃設計階段,先依國內公共工程委員會發展之公共工程經費電腦估價系統(PCCES)檢索其機、料之資源統計表,不確定處則依情境估算其碳、水足跡與環境衝擊之上、下限;再於施工階段之現地進行調查,使能與前階段之規設階段作比對驗證,其中生命週期評估需用兩種軟體SimaPro 8與Umberto碳足跡計算器,分析其碳排放量、水資源消耗量與環境衝擊,由結果相互驗證,則檢討其改善策略,以整全「價值工程」之精義為研究題旨。
研究首創於線型營建工程(路、橋、隧)提出可供進行互相比對之「正規化」功能單位。以苗栗某管推工程案例作調查;並與相同工法之既有案例先作比對驗證以確保量化數據之合理性。此調查以兩大主軸為對象,即垂直工作井開挖及水平污水套管推進求算之「正規化」功能單位:碳排放當量(tCO2e/m2/m)、單位水資源消耗量(m3/m2/m)、單位環境衝擊值(pt/m2/m, pt=point),其中相關之熱點與敏感度分析亦為檢討改善策略之執行要項。對於本案例之後續因應之減排策略亦擬作相關工、料之芻議。其排碳與水資源應可量化改善,環境衝擊值亦可降低。針對本案之工序與工項檢討其改善策略之流程再造,冀能提供後續近似耗碳量大(熱點)的地下開挖工程設計及施工之研調;與重新建構專案管理中,其價值工程指標化之增益(value-added)參佐。
英文摘要
Due to the crisis brought about by climate change and limited resources, all industries need to find solutions to prevent global warming and the greenhouse effect. For example, Taiwan’s carbon emissions were ranked 21st in the world in 2014, which civil engineering and construction industries are top of 33%. As for water consumption, Taiwan ranked 18th in the world for water usage (2015), with the average construction site using up to 10-20 ton/day of water (2013). Therefore, the construction industry not only considers progress, cost, quality and security, but also needs to mitigate carbon emissions and water consumption from the construction processes. Thus, we need to offer a reduction strategy, and choose the most sustainable and ecofriendly alternative.
Pipeline systems represent critical infrastructure that is crucial to national competitiveness around the world. In addition, underground excavation projects are the most uncertain factor during the construction. This study presents methodology for estimating the carbon footprints, water footprints, and environmental impact generated from construction processes using the LCA tools SimaPro 8 and Umberto Carbon Footprint Calculator. We carry out assessment of carbon footprints, water footprints and environmental impact of materials and machines based on the resource tables of PCCES. The proposed approach can be treated as holistic “value engineering” that identifies the opportunities to mitigate such impact by planning/design and construction stages.
We present a case study of pipe-jacking using this methodology in planning/design and construction stages. Investigation including novel normalized carbon footprints (tCO2e/m2/m), water footprints (m3/m2/m), and environmental impact (pt/m2/m). Consequential waste reduction strategy are suggested as well in this study. Environmental investigation during the underground excavation projects can be taken into account as a proper methodology for resources conservation in the near future.